1. A skid device for a rotary tilling apparatus (2), comprising: a revolution shaft (6) configured to revolve about an axis; a plurality of tillage tines (5) attached to the revolution shaft (6); a rotary machine frame (2A) configured to support one end of and the other end of the revolution shaft (6) in a direction of the axis; a skid (7) disposed on a lower portion of at least one of a left side portion and a right side portion of the rotary machine frame (2A); and a guide tool (8) disposed on a front portion of the skid (7), characterized in that the skid (7) comprises: a main body portion (7B); and a skid front portion (7A) having an inclined shape extending upwardly toward front from a front end of the main body portion (7B), and the guide tool (8) is formed to have a chevron shape tapered toward the front, and is fixed to a front surface of the skid front portion (7A) to arrange a ridge line (43) along a longitudinal direction, and a guide surface (42) is formed on a surface of the guide tool (8) on a side of the tillage tine, the guide surface (42) being configured to guide a straw (14) toward the side of the tillage tine (5).

2. The skid device for a rotary tilling apparatus (2) as claimed in claim 1, wherein the guide tool (8) comprises: an outer plate (8B) fixed on a side in a machine outward direction outside from a center of the skid front portion (7A); and an inner plate (8A) configured to connect a tip end of the outer plate (8B) to a side in a machine inward direction inside from the center of the skid front portion (7A) and configured to form a guide surface (42) having a length longer than the outer plate (8B) in a machine width direction, and a front end of the guide surface (42) is positioned between: a center of the skid front portion (7A) in a width direction; and a rim portion on a side in the machine outward direction.

3. The skid device for a rotary tilling apparatus (2) as claimed in claim 1 or 2, wherein the guide tool (8) has an attachment width equal to a width of the skid front portion (7A) in the machine width direction.

4. The skid device for a rotary tilling apparatus (2) as claimed in any one of claims 1 to 3, wherein the guide tool (8) comprises a top plate on an upper end of the guide tool (8), the top plate (8C) being configured to close an inside of the guide tool (8) from above.

5. A skid device for a rotary tilling apparatus (2), comprising: a revolution shaft (6) configured to revolve about an axis; a plurality of tillage tines (5) attached to the revolution shaft (6); a rotary machine frame (2A) configured to support one end of and the other end of the revolution shaft (6) in a direction of the axis; a skid (7) disposed on a lower portion of at least one of a left side portion and a right side portion of the rotary machine frame (2A); and a guide tool (8) disposed on a front portion of the skid (7); characterized in that a guide surface (42) disposed on the guide tool (8) on a side of the tillage tine (13), the guide surface (42) being inclined extending toward the side of the tillage tine (5) along a direction to rear and being inclined extending toward the side of the tillage tine (5) along a direction to top.

6. The skid device for a rotary tilling apparatus (2) as claimed in claim 5, wherein the guide tool (8) comprises: an inner plate (8A) forming the guide surface (42); and an outer plate (8B) extending toward an inclining direction extending toward a side opposite to the side of the tillage tine (5) along a direction from a front end of the inner plate (8A) to rear, and the inner plate (8A) and the outer plate (8B) are formed of a single flat plate bent forward to have a tapered chevron shape.

7. The skid device for a rotary tilling apparatus (2) as claimed in claim 6, wherein the skid (7) comprises: a main body portion (7B); and a skid front portion (7A) having an inclined shape extending upwardly toward front from a front end of the main body portion (7B), the guide tool (8) is disposed on a front surface of the skid front portion (7A), and a ridge line (43) of the liner plate (8A) and the outer plate (8B) stands vertically to the main body portion (7B) in a side view of the guide tool (8) shown under a state where the main body portion (7B) of the skid (7) is horizontally arranged.

8. The skid device for a rotary tilling apparatus (2) as claimed in any one of claims 5 to 7, wherein the skid (7) comprises: a main body portion (7B); and a skid front portion (7A) having an inclined shape extending upwardly toward front from a front end of the main body portion (7B), and a lower rim of the guide tool (50) is positioned under an upper end of a corner portion (48), the corner portion (48) connecting the main body portion (7B) and the skid front portion (7A) to each other, and positioned above a center portion of the corner portion (48).

9. The skid device for a rotary tilling apparatus (2) as claimed in claim 8, wherein a lower rim of the guide tool (50) is parallel to a lower surface of the main body portion (7B).

[TECHNICAL FIELD]
The present invention relates to a skid device for a rotary tilling apparatus used for tilling a paddy field.
[BACKGROUND ART]
The skid device prevents a rotary tilling apparatus from sinking, and controls a tilling depth. A rotary tilling apparatus disclosed in Patent document 1 is previously known as a rotary tilling apparatus having the skid device. The rotary tilling apparatus disclosed in Patent document 1 includes a rotary machine frame, and the skid device includes a skid, the skid being attached to a lower portion of a side portion of the rotary machine frame. The skid includes: a main body portion horizontally disposed; and a skid front portion having an inclined shape extending upwardly toward front from a front end of the main body portion. An outer rim, that is, a rim portion of the skid front portion on a machine outward side is a rim portion having an inclined shape extending backwardly toward a direction separating away from a tillage tine. In this manner, the skid front portion is formed to have a width being broadened gradually from front to rear. In addition, the skid front portion is provided with a guide wall extending upward from the outer rim.
[RELATED ART DOCUMENTS] [PATENT DOCUMENTS]
[Patent Document 1] Japanese Examined Utility Model Application Publication No. H04-7681.

[DISCLOSURE OF THE INVENTION] [PROBLEMS TO BE SOLVED BY THE INVENTION]
[0004] In the conventional technique, straws, grasses, and the like lying on a surface of the paddy field tend to be pushed away backward along the outer rim of the skid front portion when a rotary tilling apparatus is pulled by a tractor to move forward in tilling a paddy field by using the rotary tilling apparatus. In addition, the guide wall applies a reaction force to push away the straws, the grasses, and the like backward. In this manner, the straws, the grasses, and the like are prevented from being piled up on a front surface of the skid front portion.
[0005] A front surface of the guide wall, however, is a surface inclined extending backwardly toward a direction separating away from the tillage tine. Accordingly, the straws, the grasses, and the like are pushed away by the front surface of the guide wall toward a lateral side to the direction separating away from the tillage tine. That is, the conventional technique pushes away the straws, the grasses, and the like toward the lateral side of the rotary tilling apparatus to remain the straws, the grasses, and the like on an agricultural field even when it is possible to prevent the straws, the grasses, and the like from being piled up on the front portion of the skid, and thus it is hard to remove the straws, the grasses, and the like from a surface of the agricultural field.
[0006] To solve the above mentioned problems of the conventional technique, the present invention intends to provide a skid device for a rotary tilling apparatus capable of removing straws, grasses, and the like from a surface of an agricultural field.
[MEANS OF SOLVING THE PROBLEMS]
[0007] Specific techniques for solving the problems in the present invention are as follows.
A first skid device for a rotary tilling apparatus, includes: a revolution shaft configured to revolve about an axis; a plurality of tillage tines attached to the revolution shaft;

a rotary machine frame configured to support one end of and the other end of the revolution shaft in a direction of the axis; a skid disposed on a lower portion of at least one of a left side portion and a right side portion of the rotary machine frame; and a guide tool disposed on a front portion of the skid, wherein the skid includes: a main body portion; and a skid front portion having an inclined shape extending upwardly toward front from a front end of the main body portion, and the guide tool is formed to have a chevron shape tapered toward the front, and is fixed to a front surface of the skid front portion to arrange a ridge line along a longitudinal direction, and a guide surface is formed on a surface of the guide tool on a side of the tillage tine, the guide surface being configured to guide a straw toward the side of the tillage tine.
[0008] In a second skid device for a rotary tilling apparatus, the guide tool includes: an outer plate fixed on a side in a machine outward direction outside from a center of the skid front portion; and an inner plate configured to connect a tip end of the outer plate to a side in a machine inward direction inside from the center of the skid front portion and configured to form a guide surface having a length longer than the outer plate in a machine width direction, and a front end of the guide surface is positioned between: a center of the skid front portion in a width direction; and a rim portion on a side in the machine outward direction.
[0009] In a third skid device for a rotary tilling apparatus, the guide tool has an attachment width approximately equal to a width of the skid front portion in the machine width direction.
In a fourth skid device for a rotary tilling apparatus, the guide tool includes a top plate on an upper end of the guide tool, the top plate being configured to close an inside of the guide tool from above.
A fifth skid device for a rotary tilling apparatus, includes: a revolution shaft configured to revolve about an axis; a plurality of tillage tines attached to the revolution shaft; a rotary machine frame configured to support one end of and the other end of the revolution shaft in a direction of the axis; a skid disposed on a lower portion of at least one of a left side

portion and a right side portion of the rotary machine frame; a guide surface disposed on the guide tool on a side of the tillage tine, the guide surface being inclined extending toward the side of the tillage tine along a direction to rear and being inclined extending toward the side of the tillage tine along a direction to top.
[0010] In a sixth skid device for a rotary tilling apparatus, the guide tool includes: an inner plate forming the guide surface; and an outer plate extending toward an inclining direction extending toward a side opposite to the side of the tillage tine along a direction from a front end of the inner plate to rear, and the inner plate and the outer plate are formed of a single flat plate bent forward to have a tapered chevron shape.
In a seventh skid device for a rotary tilling apparatus, the skid includes: a main body portion; and a skid front portion having an inclined shape extending upwardly toward front from a front end of the main body portion, the guide tool is disposed on a front surface of the skid front portion, and a ridge line of the inner plate and the outer plate stands vertically to the main body portion in a side view of the guide tool shown under a state where the main body portion of the skid is horizontally arranged.
[0011 ] In an eighth skid device for a rotary tilling device, the skid includes: a main body portion; and a skid front portion having an inclined shape extending upwardly toward front from a front end of the main body portion, and a lower rim of the guide tool is positioned under an upper end of a corner portion, the corner portion connecting the main body portion and the skid front portion to each other, and positioned above a center portion of the corner portion,
In a ninth skid device for a rotary tilling apparatus, a lower rim of the guide tool is approximately parallel to a lower surface of the main body portion.
[EFFECTS OF THE INVENTION]
[0012] According to the present invention, the guide surface guides straws toward a side of the tillage tine, the straws being to be hanging on the skid, and thus smoothly feeds the straws. In this manner, the straws can be cut and embedded, and then the tillage

tine is capable of removing the long straws from a surface of an agricultural field.
That is, in a first invention, the guide tool is formed to have a chevron shape tapered toward the front, and is fixed to a front surface of the skid front portion to arrange a ridge line along a longitudinal direction, a guide surface is formed on a surface of the guide tool on a side of the tillage tine, the guide surface being configured to guide a straw toward the side of the tillage tine, and thus the straw is guided toward a side of the tillage tine, the straws being to be hanging on a front surface of the skid front portion, and is smoothly fed. In this manner, the straw can be cut and embedded by the tillage tine, and in particular, a long straw can be removed from a surface of an agricultural field to be prevented from being hooked again.
[0013] In addition, in a second invention, a front end of the guide surface is positioned between: a center of the skid front portion in a width direction; and a rim portion on a side in the machine outward direction, and thus the straws can be fed smoothly toward the side of the tillage tine in the greater part of a width of the skid in the machine width direction,
In a third invention, the guide tool has an attachment width approximately equal to a width of the skid front portion in the machine width direction, and thus the straw can be prevented from being piled up for an entire width of the skid.
[0014] In a fourth invention, a top plate is disposed on an upper end of the guide tool, the top plate being configured to close an inside of the guide tool from above, and thus a straw can be prevented from being hooked on an upper portion of the guide tool.
In a fifth invention, a guide surface disposed on the guide tool on a side of the tillage tine inclines extending toward the side of the tillage tine along a direction to rear, and thus the guide surface guides straws toward the side of the tillage tine, the straws being to be hanging on a front surface of the skid front portion, thereby smoothly feeding the straws. In addition, the guide surface inclines extending toward the side of the tillage tine along a direction to top, and thus the straws and the like sticking to the guide surface move upward along the guide surface. The straws having moved upward along the guide surface are lumped, and fall

down later due to the straw's own weight from the side of the upper end side of the guide surface to the side of the tillage tine. The lump of the straws having fallen down to the side of the tillage tine is cut and embedded into soil by the tillage tine.
[0015] In a sixth invention, the inner plate and the outer plate are formed of a single flat plate bent forward to have a tapered chevron shape, and thus the guide tool can be manufactured simply.
In a seventh invention, a ridge line of the inner plate and the outer plate stands vertically to the main body portion in a side view of the guide tool shown under a state where the main body portion of the skid is horizontally arranged, thereby providing a significant advantage that the straws are efficiently pushed to the left of and to the right of the guide tool when the guide tool moves forward in the paddy field.
[0016] In an eighth invention, a lower rim of the guide tool is positioned under an upper end of a corner portion, the corner portion connecting the main body portion and the skid front portion to each other, and positioned above a center portion of the corner portion, and thus a height of the lower rim of the guide tool can be a height capable of preventing the straws from remaining under the guide tool, thereby preventing the straws from remaining and being lumped under the guide tool.
In a ninth invention, a lower rim of the guide tool is approximately parallel to a lower surface of the main body portion, and thus the straws entering under the guide tool are smoothly fed backward.
[BRIEF DESCRIPTION OF THE DRAWINGS] [0017]
FIG. 1 is a left side view showing an embodiment of the present invention; FIG. 2 is a plan view showing the same; FIG. 3 is a right side view showing the same; FIG. 4 is a cross-sectional back view showing the same; FIG. 5 is a front surface view of a skid device on a side of a side frame;

FIG. 6 is a perspective view showing a skid device on a side of a side frame according to a second embodiment;
FIG. 7 is a perspective view showing a rotary tilling apparatus according to a third embodiment;
FIG. 8 is a side view showing a skid device on a left side according to the third embodiment;
FIG. 9 is a plan view showing the skid device on the left side according to the third embodiment;
FIG. 10 is a front view showing the skid device on the left side according to the third embodiment:
FIG. 11 is a perspective view showing the skid device on the left side according to the third embodiment, being seen upwardly and diagonally from front;
FIG. 12 is a view taken along the line A-A of FIG. 10;
FIG. 13 is a view taken along the line B-B of FIG. 9;
FIG. 14 is a side view showing a skid device on a right side according to the third embodiment;
FIG. 15 is a plan view showing the skid device on the right side according to the third embodiment;
FIG. 16 is a front view showing the skid device on the right side according to the third embodiment;
FIG. 17 is a perspective view showing the skid device on the right side according to the third embodiment, being seen upwardly and diagonally from front;
FIG. 18 is a view taken along the line C-C of FIG. 16;
FIG. 19 is a view taken along the line D-D of FIG. 15;
FIG. 20 is a side view showing a front lower portion of the skid device on the left side;
FIG. 21 is a side view showing a front lower portion of the skid device on the right side; and

FIG. 22 is a perspective view showing the skid device.
[BEST MODE FOR CARRYING OUT THE INVENTION]
[0018] Referring to drawings, embodiments of the present invention will be described below.
FIG. 1 to FIG. 5 show a rotary tilling apparatus 2 of a side drive type according to a first embodiment. The rotary tilling apparatus 2 is coupled to a rear portion of a tractor vehicle body 11 by a three-point link mechanism 12, and is capable of being freely lifted and lowered.
FIG. 1 and FIG 3 show side views of the rotary tilling apparatus 2, and FIG. 2 shows a plan view of the rotary tilling apparatus 2. In the embodiment of the present invention, a front direction corresponds to an direction shown by an arrowed line A1 in FIG. 1 and FIG. 3, a rear direction corresponds to an direction shown by an arrowed line A2 in FIG. 1 and FIG 3, a left direction corresponds to an direction shown by an arrowed line Bl in FIG. 2, and a right direction corresponds to an direction shown by an arrowed line B2 in FIG. 2, and thus the explanation will be described using the terms.
[0019] In addition, as shown in FIG. 2, a machine width direction XI corresponds to a horizontal direction that is a direction perpendicular to a front to rear direction in the rotary tilling apparatus 2, and thus the explanation will be described using the term. A direction from a center portion of the rotary tilling apparatus 2 toward a right portion of or a left portion of the rotary tilling apparatus 2 can be referred to as a machine outward direction, and thus the explanation will be described using the term. In other words, the machine outward direction corresponds to the machine width direction XI, that is, a direction separating from the rotary tilling apparatus 2. A direction opposite to the machine outward direction can be referred to as a machine inward direction, and thus the explanation will be described using the term. In other words, the machine inward direction corresponds to the machine width direction XL that is, a direction being closer to the rotary tilling apparatus 2.

[0020] As shown in FIG. 1 to FIG. 4, the rotary tilling apparatus 2 includes a rotary machine frame 2A and a skid device 3. The rotary machine frame 2A includes a gear case 15, a support arm 16L and 16R, a transmission case 37, and a side frame 18.
The gear case 15 is positioned approximately on a center portion of the rotary tilling machine 2 in the machine width direction XI. The support arm 16L protrudes from a left side portion of the gear case 15 toward the machine outward direction (a left side). The support arm 16R protrudes from a right side portion of the gear case 15 toward the machine outward direction (a right side). In other word, the gear case, the support arm 16L on the left side, and the support arm 16R on the right side are arranged in parallel with each other,
[0021] The transmission case 17 is attached to an outer rim (a rim portion on the machine outward side) of the support arm 16L at an upper portion of the transmission case 17. The side frame 18 is attached to an outer rim of the support arm 16R at an upper portion of the side frame 18. In other word, the transmission case 17 and the side frame 18 are disposed extending downward from side portions of the support arms 16L and 16R.
As shown in FIG. 4, a support shaft (a revolution short shaft) 19L is disposed on a lower portion of the transmission case 17, and is capable of revolving about a lateral axis (an axis in the machine width direction XI). A support shaft (a revolution short shaft) 19R is disposed on a lower portion of the side frame 18, and is capable of revolving about the lateral axis (the axis in the machine width direction XI). A revolution shaft (a tine shaft) 6 is arranged between the support shaft 19L and the support shaft 19R, the revolution shaft 6 having an axis in the machine width direction XI. A left end of the revolution shaft 6 is coupled to the support shaft 19L. A right end of the revolution shaft 6 is coupled to the support shaft 19R. The revolution shaft 6 is supported by the rotary machine frame 2A at one end of and at the other end of the revolution shaft 6 in an axial direction, and the revolution shaft 6 revolves about the axis.
[0022] The rotary machine frame 2A includes a left support stay 20, a right support stay 20, and a mast 21. A rear end of a lower link 22 is coupled to the left support stay 20 and to the right support stay 20, the lower link 22 being included in the three-point

link mechanism 12. A top link 23 is coupled to the mast 21, the top link 23 being included in the three-point link mechanism 12.
The gear case 15 is provided with an input shaft 28. A motive power of a PTO shaft 24 of the tractor vehicle body 11 is transmitted to the input shaft 28, transmitting through a joint 25. The motive power transmitted to the input shaft 28 is transmitted to a chained transmission means 32 in the transmission case 17 through a gear 29 in the gear case 15 and through a transmission shaft 30 in a support arm 16L. The motive power transmitted to the chained transmission means 32 drives the support shaft 19L and the revolution shaft 6.
[0023] The revolution shaft 6 is a shaft member formed to have a cylindrical shape. A large number of brackets 31 are fixed to an outer circumference of the revolution shaft 6. A tillage tine 5 is fixed to each of the brackets 31. A tillage unit 13 is formed of the revolution shaft 6 and the tillage tine 5. The revolution shaft 6 revolves in a direction shown by an arrowed line Yl in FIGs. 1 and 3. A curved-knife tine (a curved -hatchet tine) 22B and a normal tine are used as the tillage tine 5. In addition, the tillage tine 5 may be an L-shaped tine. The L-shaped tine is bent, and thus the tillage tine 5, from the approximate center thereof to a tip end portion thereof, extends toward a side of the transmission case 17 or a side of the side frame 18.
[0024] The rotary machine frame 2A includes a left side plate 34, a right side plate 34, and a front frame member 35 configured to connect a front portion of the left side plate 34 and a front portion of the right side plate 34 to each other. The left side plate 34 is fixed to a surface of the transmission case 17 on the machine inward side. The right side plate 34 is fixed to a surface of the side frame 18 on the machine inward side. Amain cover 36 is attached to the left side panel 34, to the right side panel 34, and the front frame member 35, the main cover being configured to cover an upper portion of the tillage unit 13. The main cover 36 is supported approximately at a center potion of the main cover 36 by the gear case 15, using a fixation member 37 as an intermediary.
[0025] The left support stay 20 and the right support stay 20 are disposed on the front frame member 35 and on the main cover 36. The mast 21 is supported by the left

support stay 20 and by the right support stay 20. A rear cover 38 is pivotally supported by a rear portion of the main cover 36, the rear cover 38 being configured to cover a rear portion of the tillage unit 13. An elastically pressing means 39 is disposed between: the rear cover 38; and rear portions of the left support stay 20 and of the right support stay 20, the elastically pressing means 39 being configured to apply an uniform pressure to the rear cover 38.
A skid device 3 (a skid 7, a stay member 9, and a guide tool 8) is disposed on each of: a side portion (the left side portion) of the rotary machine frame 2A on the left side; and a side portion (the right side portion) of the rotary machine frame 2 A on the right side. In particular, the skid device 3 is attached to the transmission case 17 and to the side frame 18, and is capable of freely adjusting a height position and of being freely attached to and detached from. The skid device 3 is disposed on each of outer side surfaces of the transmission case 17 and the side frame 18, being approximately symmetrical about the machine width direction XI.
[0026] Meanwhile, the skid device 3 (the skid 7, the stay member 9, and the guide tool 8) may be disposed on at least either one of the left side portion of and the right side portion of the rotary machine frame 7.
The left skid device 3 and the right skid device 3 each include the skid 7, the stay member 9, and the guide tool (a straw ejection tool) 8. The skid 7 includes: a main body portion 7B formed to be fiat; and a skid front portion 7A extending from a front end of the main body portion 7B. The skid front portion 7A has an inclined shape extending upwardly toward front from the front end of the main body portion 7B (a shape inclined being curved upwardly toward front). The stay member 9 is a member for freely attaching and detaching the skid 7 to and from the outer side surface of each of the transmission case 17 and the side frame 18. The stay member 9 is disposed on the rear portion of the main body portion 7B and on the lower portion of the skid front portion 7A. The guide tool 8 is fixed to the front surface of the skid front portion 7A.
[0027] The skid 7 is formed of a plate member having a strip shape, and a front portion of the plate member is bent to form the main body portion 7B and the skid front

portion 7A. In addition, a lower end of the stay member 9 disposed on the front side is attached by welding to an upper surface of the skid front portion 7A in the vicinity of the bending portion of the skid 7. Moreover, a lower end of the say member 9 disposed on the rear side is attached by welding to a rear portion of an upper surface of the main body portion 7B of the skid 7. Furthermore, the skid front portion 7A is warped up, and thereby a front surface of the skid front portion 7A faces front and diagonally downward. A left end portion of and a right end portion of the guide tool 8 are attached by welding to the front surface of the skid front portion 7A facing front and diagonally downward.
[0028] A plurality of bolt holes 9a are formed in each of the stay members 9 along a longitudinal direction (a vertical direction). Each of the stay members 9 is fastened to an outer side surface of each of the transmission case 17 and the side frame 18 by a fastening tool 10 (a bolt), and is capable of freely adjusting a height position.
The stay members 9 disposed on the front and on the rear can adjust the attachment positions thereof, and thereby adjusting a height of or a horizontal angle of the main body portion 7B of the skid 7 with respect to the rotary tilling apparatus 2. In this manner, the tilling depth of the rotary tilling apparatus 2 can be adjusted,
[0029] For example, in order to deepen the tilling depth of the rotary tilling apparatus 2, the skid device 3 changes the positions of the stay members 9 upward with respect to the rotary machine frame 2A, and simultaneously adjusts the main body portion 7B of the skid 7 to be horizontal with respect to the agricultural field.
The left skid 7 and the right skid 7 arrange a side close to the tilling unit 13 including the revolution shaft 6 on the machine inward side, and arrange a side far from the tilling unit 13 on the machine outward side. As shown in FIG. 5, the guide tool 8 includes an inner plate (an inner side plate) 8A, an outer plate (an outer side plate) 8B, and a top plate 8C. A rear rim of the outer plate 8B is fixed to an outer rim side, that is, a rim portion of the skid front portion 7A on the machine outward side. A rear rim of the inner plate 8A is fixed to an inner rim side, that is, a rim portion of the skid front portion 7A on the machine inward side. The top plate 8C is fixed to upper ends of the outer plate 8B and of the inner 8A.

[0030] A front portion of the inner plate 8A is fixedly attached to a tip end of the outer plate 8B. The inner plate 8 connects a tip end of the outer plate 8B to the skid front portion 7A That is, the tip end of the outer plate 8B and an inner rim side of the skid front portion 7A are connected to each other by the inner plate 8 A. The front end of the inner plate 8A protrudes forward from the outer plate 8B, and is extended to a position approximately corresponding to an outer rim of the skid front portion 7A. That is, the inner plate 8A is longer than the outer plate 8B regarding a length in the machine width direction XI.
[0031 ] The inner plate 8A has a width occupying in the machine width direction XI, the width being approximately equal to a width of the front surface of the skid front portion 7A. The inner plate 8A forms a surface to which long straws 14 (shown in FIG 14, and including long residue such as grasses) contact, the long straws 14 being to be hanging on the skid front portion 7A. The surface is a surface inclined from the front end to the rear end extending toward the machine inward (the tillage tine 5) side. And, the surface serves as a guide surface (a straw ejection surface) 42 for guiding (feeding and removing) the straws 14 toward a side of the revolution shaft 6 (a side of the tillage tine), the straws 14 being to be hanging on.
[0032] As clearly shown in the plan view of FIG. 2 and in the front view of FIG. 5, the guide tool 8 has a chevron shape (a V-shape) having one side longer than the other side, and thus has a chevron shape tapered toward the front (forming an approximate triangle made of the guide tool 8 and the front surface of the skid front portion 7A). A ridge line 43 of the guide tool 8 having the chevron shape extends along a longitudinal direction, and is approximately parallel to the front surface of the skid front portion 7A. That is, the guide tool 8 is fixed to the front surface of the skid front portion 7A, and thus the ridge line 43 of the chevron shape, from a lower portion to an upper portion, takes a position inclined forward.
[0033] Based on the ridge line 43, the inner plate 8A is positioned on the machine inward in comparison to the ridge line 43, and the outer plate 8B is positioned on the machine outward in comparison to the ridge line 43.

An area of the guide surface 42 of the Inner plate 8A is larger than an area of a surface of the outer plate 8B. A length of the guide surface 42 of the inner plate 8A in the machine width direction XI is larger than a length of the outer plate 8B in the machine width direction XI. Thus, the front end of the guide surface 42 is positioned between: the outer rim; and a center (a center line 46) of the skid front portion7A in the width direction.
[0034] A rear end of the inner plate 8 A is fixed in the vicinity of the inner rim of the skid front portion 7A, a rear end of the outer plate 8B is fixed in the vicinity of the outer rim of the skid front portion 7A, and thus an attachment width 8W of the guide tool 8 is approximately equal to a width 7W of the skid front portion 7A in the machine width direction XL In this manner, the guide tool 8 is firmly attached to the skid front portion 7A. In addition, the outer plate 8B serves as a plate for supporting the inner plate 8A, thereby increasing a strength of the guide tool 8.
[0035] Meanwhile, the outer plate 8B of the guide tool 8 is required to be fixed outward in comparison to the center of the skid front portion 7A, and the inner plate 8 A is required to be fixed inward in comparison to the center of the skid front portion 7A.
The top plate 8C of the guide tool 8 closes a space between the inner plate 8 A and the outer plate 8B from above. The top plate 8C prevents the straws 14 from entering the space between the inner plate 8 A and the outer plate 8B, and from hanging on the upper ends of the inner piate 8A and of the outer plate 8B. In addition, the provision of the top plate 8C increases the strength of the guide tool 8.
[0036] In the skid 7 of the skid device 3. the main body portion 7B contacts the paddy field in a horizontal posture, and the skid front portion 7A contacts the paddy field in a posture inclining forward, in tilling a paddy field by using the rotary tilling apparatus 2. The guide tool 8 of the front surface of the skid front portion 7A runs in front of the skid front portion 7A; thus the long straws 14 are hanged on the guide tool 8, and the straws 14, soil, and the like hit the guide surface 42. The straws 14 hitting the guide surface 42 are guided by the guide surface 42 from the machine outward side to the machine inward side, and are fed to a side of the tilling unit 13. The straws 14 fed to the side of the tilling unit 13 are

pulled by the tillage tine 5, and thus are cut by the tillage tine 5 and embedded into the soil.
[0037] Though some of the straws 14 hang on the tip end of the guide tool 8 and are not fed, the straws 14 are pulled to be cut and embedded by the tillage tine 5 when the straws 14 are hooked by the tillage tine 5. In addition, since the tip end of the inner plate 8A is arranged on a position corresponding to the outer rim of the skid front portion 7 A, the straws 14 can be fed smoothly toward the tillage tine in the greater part of a width of the skid 7 in the machine width direction, and thus is prevented from being piled up. In this manner, the straws 14 remaining in the paddy field can be cut and embedded in the approximate maximum width of the rotary tilling apparatus 2.
[0038] FIG. 6 shows a second embodiment. The guide tool 8 according to the second embodiment is formed of a single piece of plat plate, the flat plate being bent to have a V-shape and forming the inner plate 8A and the outer plate 8B. In addition, an area of the inner plate 8 A forming the guide surface 42 is larger than an area of the outer plate 8B, Moreover, a rear rim of the inner plate 8A is attached by welding in the vicinity of an inner rim of the skid front portion 7A. Furthermore, a rear rim of the outer plate 8B is attached by welding in the vicinity of the outer rim of the skid front portion 7A.
[0039] The guide tool 8 according to the second embodiment can be formed simply and rigidly. In addition, the outer plate 8B may be arranged along the front to rear direction, and thus the guide tool 8 and a front surface of the skid front portion 7A form a right-angled triangle.
Meanwhile, shapes of and positional relationships of the members according to the embodiment, the positional relationships depending on the front and the rear, the machine width direction, and the up and the down, may employ the configurations shown in FIG. 1 to FIG. 6 as the best configurations. However, the shapes and the positional relationships are not limited to the embodiment mentioned above; thus the members and configurations may be variously modified, and a combinations may be changed,
[0040] For example, the skid device 3 is disposed on each of the transmission case 17 and the side frame 18 but may be disposed on either one, and the guide tool 8 may be

formed integrally by folding the top plate 8C from the inner plate 8A or from the outer plate 8B.
FIG. 7 to FIG. 22 show a third embodiment. FIG. 7 shows a perspective view of the rotary tilling apparatus. FIG. 8 to FIG. 13 show the skid device 3 disposed on the left side. FIG. 14 to FIG. 19 show the skid device 3 disposed on the right side. As shown in FIG. 11, FIG. 12, FIG. 17, and FIG. 18, the guide tool 8 according to the third embodiment includes the inner plate 8A and the outer plate 8B as in the second embodiment. The inner plate 8A and the outer plate 8B are formed of a single flat plate bent to have a V-shape. In other words, a single flat plate is bent toward the front to have a tapered chevron shape, thereby forming the inner plate 8A and the outer plate 8B. In this manner, the guide tool 8 can be manufactured easily.
[0041] In addition, an area of the inner plate 8 A forming the guide surface 42 is larger than the outer plate 8B. Moreover, the rear rim of the inner plate 8A is attached by welding in the vicinity of the inner rim of the skid front portion 7A. Furthermore, the rear rim of the outer plate 8B is attached by welding in the vicinity of the outer rim of the skid front portion 7 A. A reinforce plate 44 is fixedly attached to an upper surface of the main body portion 7B of the skid 7.
As shown in FIG. 12, FIG. 13, FIG. 18, and FIG. 19, the inner plate 8A has an inclined shape inclining from the front end to the rear to gradually extend toward a side of the tillage tine and gradually extending toward the side of the tillage tine along a direction from below to top. That is, the guide surface 42 is similarly inclining from the front end to the rear to extend toward a side of the tillage tine and extending toward the side of the tillage tine along a direction from below to top.
[0042] Meanwhile, considering the machine width direction XI on the basis of the guide tool 8, the side of the tillage tine corresponds to one side in the machine width direction XI, and the tillage tine 5 is positioned on the one side. A position opposite to the side of the tillage tine corresponds to the other side in the machine width direction XI, and the tillage tine 5 is not positioned on the other side.

In addition, the outer plate 8B extends toward an inclining direction extending toward a side opposite to the side of the tillage tine along a direction from the front end to the rear. Moreover, the outer plate 8B is inclined extending toward the side of the tillage tine along a direction from below to the top.
[0043] As shown in FIG. 10 and FIG. 16, the ridge line 43 of the guide tool 8 (the inner plate 8A and the outer plate 8B) is inclined extending toward the machine inward side along a direction to the top in a front view of the guide tool 8 shown under a state where the main body portion 7B of the skid 7 is horizontally arranged. In addition, as shown in FIG. 8 and FIG. 14, the ridge line 43 stands vertically to the main body portion 7B (along the vertical direction) in a side view of the guide tool 8 shown under a state where the main body portion 7B of the skid 7 is horizontally arranged. In other words, the ridge line 43 is non-inclined (is not inclined) with respect to a direction perpendicular to the machine body portion 7B in a side view of the guide tool 8 shown under a state where the main body portion 7B of the skid 7 is horizontally arranged.
[0044] As shown in FIG. 9 and FIG. 15, the outer rim of the skid front portion 7A is formed to have a shape inclined extending toward the machine inward direction along a direction to the front. In this manner, a width of the skid front portion 7A is formed to be gradually narrowed toward the front,
As shown in FIG. 20 and FIG. 21, a corner portion 48 is formed to have a curved shape (a circular arc shape) being convex downward and diagonally forward, the corner portion 48 being configured to connect the main body portion 7B and the skid front portion 7A to each other. As shown in FIG. 9 and FIG. 15, a lower surface of the guide tool 8 is formed to have a shape inclined extending upward along a direction from the machine inward direction to the machine outward direction. In this manner, as shown in FIG. 20 and FIG. 21. the lower rim 50 of the inner plate 8A is positioned above the lower rim 56 of the outer plate 8B. Thus, the lower rim 50 of the inner plate 8A is a lower rim of the guide tool 8. The lower rim 50 of the guide tool 8 is approximately parallel to the lower surface 54 of the main body portion 7B. To be detailed, the lower rim 50 of the guide tool 8 is slightly inclined

upward along a direction to the front. In addition, the lower rim 56 of the outer plate 8B is also slightly inclined upward along the direction to the front,
[0045] The lower rim 50 of the guide tool 8 is positioned within a range of a height H1 of the corner portion 48. That is, the lower rim 50 of the guide tool 8 is positioned within a range of vertical interval between an upper end 48a of the corner portion 48 and a lower end 48b of the corner portion 48. In addition, the lower rim 50 of the guide tool 8 is positioned above a center portion 52 of the comer portion 48. The center portion 52 of the corner portion 48 is at a center of a curved line LI (at a position corresponding to a half of the curved line LI), where the curved line LI is a curved line having a circular arc shape connecting the upper end 48a of and the lower end 48b of the corner portion 48 along the corner portion 48.
[0046] In the third embodiment, the guide surface 42 is inclined extending toward the side of the tillage tine along a direction to the rear. In this manner, as shown by an arrowed line Q in FIG. 22, the straws hitting the guide surface 42 is guided by the guide surface 42 toward the machine inward side to be fed toward the side of the tillage unit 13 (the side of the tillage tine), being similar to the first embodiment and to the second embodiment. In addition, the guide surface 42 is inclined extending toward the side of the tillage tine along the direction to the top, and thus a part of the straws hitting the guide surface 42 moves upward along the guide surface 42 to move toward the side of the tillage tine. Moreover, a part of the straws having moved upward along the guide surface 42 is lumped on an upper portion of the guide surface 42. The straws lumped on the upper portion of the guide surface 42 falls down later due to the straw's own weight from the side of the upper end side of the guide surface 42 to the side of the tillage tine. The lump of the straws having fallen down on the side of the tillage tine is pulled by the tillage tine 5, and thus is cut and embedded into the soil by the tillage tine 5. In this manner, the straws lying on the agricultural field can be prevented from being piled up on the guide surface 42.
[0047] In addition, the ridge line 43 of the guide tool 8 stands vertically to the main body portion 7B in the side view of the guide tool 8 shown under a state where the main

body portion 7B of the skid 7 is horizontally arranged, thereby providing a significant advantage that the straws are efficiently pushed to the left of and to the right of the guide tool S when the guide tool 8 moves forward in the paddy field. In this manner, the straws are prevented from entering under the guide tool 8, and thus clogging of the straws is prevented under the guide tool 8.
[0048] In addition, the lower rim 50 of the guide tool 8 is positioned under the height HI of the corner portion 48 and above the center portion 52 of the comer portion 48, the corner portion connecting the main body portion 7B and the skid front portion 7A to each other, and thus a height of the lower rim 50 of the guide tool 8 is a height capable of preventing the straws from remaining under the lower rim 50, thereby preventing the straws from remaining and being lumped under the guide tool 8.
Moreover, the lower rim 50 of the guide tool 8 is approximately parallel to the lower surface 54 of the main body portion 7B, and thus the straws entering under the guide tool 8 are fed backward.
[0049] In the above description, the embodiments of the present invention has been explained. However, all the features of the embodiments disclosed in this application should be considered just as examples, and the embodiments do not restrict the present invention accordingly. A scope of the present invention is shown not in the above-described embodiments but in claims, and is intended to include ail modifications within and equivalent to a scope of the claims.
[DESCRIPTION OF THE REFERENCE NUMERAL] [0050] 2 Rotary tilling apparatus 2A Rotary machine frame 3 Skid device
5 Tillage tine
6 Revolution shaft
7 Skid

7 A Skid front portion
7B Main body portion
8 Guide tool 8A Inner plate 8B Outer plate
9 Stay member

13 Tillage unit
14 Straws

17 Transmission case
18 Side frame

42 Guide surface
43 Ridge line
48 Corner portion
50 Lower rim of the guide tool
52 Center of the corner portion
H1 Height of the corner portion

WE CLAIM:
1. A skid device for a rotary tilling apparatus (2), comprising:
a revolution shaft (6) configured to revolve about an axis;
a plurality of tillage tines (5) attached to the revolution shaft (6);
a rotary machine frame (2A) configured to support one end of and the other end of the revolution shaft (6) in a direction of the axis;
a skid (7) disposed on a lower portion of at least one of a left side portion and a right side portion of the rotary machine frame (2A); and
a guide tool (8) disposed on a front portion of the skid (7),
characterized in that the skid (7) comprises: a main body portion (7B); and a skid front portion (7A) having an inclined shape extending upwardly toward front from a front end of the main body portion (7B), and
the guide tool (8) is formed to have a chevron shape tapered toward the front, and is fixed to a front surface of the skid front portion (7A) to arrange a ridge line (43) along a longitudinal direction, and
a guide surface (42) is formed on a surface of the guide tool (8) on a side of the tillage tine, the guide surface (42) being configured to guide a straw (14) toward the side of the tillage tine (5).
2. The skid device for a rotary tilling apparatus (2) as claimed in claim 1, wherein
the guide tool (8) comprises:
an outer plate (8B) fixed on a side in a machine outward direction outside from a center of the skid front portion (7A); and
an inner plate (8A) configured to connect a tip end of the outer plate (8B) to a side in a machine inward direction inside from the center of the skid front portion (7A) and configured to form a guide surface (42) having a length longer than the outer plate (8B) in a machine width direction, and
a front end of the guide surface (42) is positioned between: a center of the skid front portion (7A) in a width direction; and a rim portion on a side in the machine outward direction.

3. The skid device for a rotary tilling apparatus (2) as claimed in claim 1 or 2, wherein the guide tool (8) has an attachment width equal to a width of the skid front portion (7A) in the machine width direction.
4. The skid device for a rotary tilling apparatus (2) as claimed in any one of claims 1 to 3, wherein the guide tool (8) comprises a top plate on an upper end of the guide tool (8), the top plate (8C) being configured to close an inside of the guide tool (8) from above.
5. A skid device for a rotary tilling apparatus (2), comprising:
a revolution shaft (6) configured to revolve about an axis;
a plurality of tillage tines (5) attached to the revolution shaft (6);
a rotary machine frame (2A) configured to support one end of and the other end of the revolution shaft (6) in a direction of the axis;
a skid (7) disposed on a lower portion of at least one of a left side portion and a right side portion of the rotary machine frame (2A); and
a guide tool (8) disposed on a front portion of the skid (7);
characterized in that a guide surface (42) disposed on the guide tool (8) on a side of the tillage tine (13), the guide surface (42) being inclined extending toward the side of the tillage tine (5) along a direction to rear and being inclined extending toward the side of the tillage tine (5) along a direction to top.
6. The skid device for a rotary tilling apparatus (2) as claimed in claim 5, wherein
the guide tool (8) comprises:
an inner plate (8A) forming the guide surface (42); and
an outer plate (8B) extending toward an inclining direction extending toward a side opposite to the side of the tillage tine (5) along a direction from a front end of the inner plate (8A) to rear, and
the inner plate (8A) and the outer plate (8B) are formed of a single flat plate bent forward to have a tapered chevron shape.

7. The skid device for a rotary tilling apparatus (2) as claimed in claim 6, wherein
the skid (7) comprises:
a main body portion (7B); and
a skid front portion (7A) having an inclined shape extending upwardly toward front from a front end of the main body portion (7B),
the guide tool (8) is disposed on a front surface of the skid front portion (7A), and
a ridge line (43) of the liner plate (8A) and the outer plate (8B) stands vertically to the main body portion (7B) in a side view of the guide tool (8) shown under a state where the main body portion (7B) of the skid (7) is horizontally arranged.
8. The skid device for a rotary tilling apparatus (2) as claimed in any one of claims 5
to 7, wherein the skid (7) comprises:
a main body portion (7B); and
a skid front portion (7A) having an inclined shape extending upwardly toward front from a front end of the main body portion (7B), and
a lower rim of the guide tool (50) is positioned under an upper end of a corner portion (48), the corner portion (48) connecting the main body portion (7B) and the skid front portion (7A) to each other, and positioned above a center portion of the corner portion (48).
9. The skid device for a rotary tilling apparatus (2) as claimed in claim 8, wherein a
lower rim of the guide tool (50) is parallel to a lower surface of the main body portion
(7B).