FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See Section 10, and rule 13}
1. TITLE OF INVENTION
STRUCTURE FOR SUPPRESSING COLUMN HEAT DEFORMATION IN MACHINE TOOLS
2. APPLICANT(S)
a) Name : MITSUBISHI HEAVY INDUSTRIES, LTD.
b) Nationality : JAPANESE Company
c) Address : 16-5, KONAN 2-CHOME,
MINATO-KU, TOKYO 1088215, JAPAN
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed :-

TECHNICAL FIELD
The present invention relates to a structure for suppressing column heat deformation in a machine tool which is capable of suppressing heat deformation of a column.
BACKGROUND ART
In general, a machine tool such as a horizontal boring machine is provided with a column which is formed in a hollow structure. A saddle configured to rotatably support a main spindle is slidably supported on a front surface of this column. Among such machine tools, a machine tool is provided that includes a sliding surface cover such as a telescopic cover or a bellows cover for protecting a sliding surface of a column against chips, cutting fluids, and the like. Meanwhile, in such a machine tool, the column is designed to possess high rigidity so as to prevent its heat deformation due to an influence of a change in the temperature around the machine tool or an influence of heat generated from the machine tool.
However, when the machine tool is provided with the sliding surface cover as described above, the cover makes the sliding surface of the column less likely to contact outside air. In addition, a space surrounded by the sliding surface of the column and an inner surface of the sliding surface cover is kept at a high temperature due to heat generation by main spindle driving means located inside the saddle. This situation leads to thermal imbalances in a front-back direction and in a left-right direction of the column, and may cause heat deformation of the column as a consequence. If the heat deformation occurs in the column as described above, there is a risk of degradation in straightness at the time of sliding the saddle and the resulting adverse effect on machining accuracy.
Accordingly, various measures for suppressing the heat deformation of the column have heretofore been taken in order to cope with the deterioration in the machining accuracy as mentioned above. Such a conventional structure for suppressing column heat deformation in a machine tool is disclosed in Patent Document 1, for example.

PRIOR ART DOCUMENT PATENT DOCUMENT
Patent Document 1: Japanese Examined Patent Application Publication No.
Hei 7-49181
SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
The above-described conventional structure for suppressing column heat deformation in a machine tool is configured to control the expansion and contraction of a column by heating and cooling the column by using actuators in response to an amount of heat deformation of the column. However, the conventional structure needs to be provided with numerous sensors for detecting the heat deformation of the column as well as numerous heating and cooling actuators to be driven in response to detection results of the sensors inside and outside the column. As a consequence, large-scale installation work is required.
The present invention has therefore been made to solve the aforementioned problem, and an object thereof is to provide a structure for suppressing column heat deformation in a machine tool which is capable of suppressing heat deformation of a column without requiring large-scale installation work.
MEANS FOR SOLVING PROBLEMS
A structure for suppressing column heat deformation in a machine tool according to a first invention to solve the foregoing problems comprises: a saddle configured to rotatably support a main spindle to which a tool is detachably attached; a column including a sliding surface configured to slidably support the saddle; a sliding surface cover provided in such a manner as to cover the sliding surface, and configured to expand and contract along with slide of the saddle; and air supplying means for supplying air to the inside of the sliding surface cover.

The structure for suppressing column heat deformation in a machine tool according to a second invention to solve the foregoing problems is characterized in that the air supplying means comprises an intra-cover air supply channel extending along the sliding surface and penetrating the saddle, and intra-cover injection holes communicating with the inside of the saddle and the inside of the sliding surface cover are formed in the intra-cover air supply channel.
The structure for suppressing column heat deformation in a machine tool according to a third invention to solve the foregoing problems is characterized in that the air supplying means comprises a saddle air supply channel communicating with the inside of the saddle, and a saddle injection hole connected to the saddle air supply channel and communicating with the inside of the sliding surface cover is formed in the saddle.
EFFECTS OF THE INVENTION
The structure for suppressing column heat deformation in a machine tool according to the present invention, therefore, includes the air supplying means for supplying air into a telescopic cover. Thus, the structure is capable of suppressing heat deformation of the column without requiring large-scale installation work.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a front view of a structure for suppressing column heat deformation in a machine tool according to a first embodiment of the present invention.
Fig. 2 is a plan view of the structure for suppressing column heat deformation in a machine tool according to the first embodiment of the present invention.
Fig. 3 is a front view of a structure for suppressing column heat deformation in a machine tool according to a second embodiment of the present invention.

Fig. 4 is a side view of the structure for suppressing column heat deformation in a machine tool according to the second embodiment of the present invention.
MODES FOR CARRYING OUT THE INVENTION
A structure for suppressing column heat deformation in a machine tool according to the present invention will be described below in detail by using the drawings.
FIRST EMBODIMENT
A first embodiment of the present invention will be described in detail by using Fig. 1 and Fig. 2, to begin with.
As shown in Fig. 1 and Fig. 2, a machine tool 1 which is a horizontal boring machine is provided with a bed 11 to be fixed to a floor surface F, and a column base 12 is supported on an upper part of this bed 11 in such a manner that the column base 12 is slidable in a horizontal direction. Moreover, a column 13 which is a hollow structure is vertically installed on an upper surface of the column base 12, and a pair of left and right guide rails 14a, 14b extending in the vertical direction are provided on a sliding surface 13a which is a front surface of this column 13. A saddle 15 is slidably supported by the sliding surface 13a of the column 13 and by the guide rails 14a, 14b, and a main spindle 16 is supported inside this saddle 15 in such a manner that the main spindle 16 is rota table about a horizontal axis. Further, a tool T is detachably attached to a tip end of the main spindle 16. An unillustrated workpiece is processed by this tool T.
An upper telescopic cover (a sliding surface cover) 17 and a lower telescopic cover (a sliding surface cover) 18 are provided at an upper part and a lower part of the saddle 15, respectively, in such a manner as to surround the sliding surface 13a of the column 13. The upper telescopic cover 17 and the lower telescopic cover 18 are respectively formed of multiple (four each in Fig. 1) covers 17a, 17b, 17c, 17d and covers 18a, 18b, 18c, 18d, which are shaped like a frame and are mutually slidably

stacked on one another.
In the upper telescopic cover 17, the fixed cover 17a located in the highest position is fixed to the column 13 while the movable covers 17b to 17d located below this fixed cover 17a are slidably supported by the column 13. Moreover, among the movable covers 17b to 17d, the movable cover 17d located in the lowest position is fixed to an upper surface of the saddle 15.
Meanwhile, in the lower telescopic cover 18, the fixed cover 18a located in the lowest position is fixed to the column 13 while the movable covers 18b to 18d located above this fixed cover 18a are slidably supported by the column 13. Moreover, among the movable covers 18b to 18d, the movable cover 18d located in the highest position is fixed to a lower surface of the saddle 15.
Accordingly, the telescopic covers 17,18 as a whole are expandable and contractable in the up-down direction in conjunction with the slide of the saddle 15, and are thus configured to shield the sliding surface 13a of the column 13 from an external environment. By this, the sliding surface 13a of the column 13 that slidably supports the saddle 15 is protected against chips, cutting fluids, and the like which scatter during machining.
A blower 30 (air supplying means) 30 is installed on an upper surface of the column 13. This blower 30 is configured to blow outside air which is taken therein. Meanwhile, an air supply pipe (an intra-cover air supply channel) 41 is connected to the blower 30, and this air supply pipe 41 is arranged in such a manner as to extend in the vertical direction along the sliding surface 13a of the column 13 and to penetrate a through-hole 15a in the saddle 15 on the way. Moreover, multiple injection holes (intra-cover injection holes) 41a are formed in the air supply pipe 41 at given intervals in a longitudinal direction thereof. Incidentally, the through-hole 15a communicates with the inside of the saddle 15.
Accordingly, when the blower 30 is driven, the outside air around the machine tool 1

(the column 13) is taken into the blower 30, and is then jetted out of the injection holes 41a in the air supply pipe 41 and supplied into the saddle 15 and into the telescopic covers 17,18. Thereafter, the outside air supplied into the saddle 15 and into the telescopic covers 17,18 is discharged from an upper opening of the upper telescopic cover 17, gaps between the covers 17a to 17d, and gaps between the covers 18a to 18d.
In this respect, the blower 30 is configured to be driven simultaneously with the starting of the operation of the machine tool 1, and the outside air taken into this blower 30 is designed to be always supplied into the saddle 15 and into the telescopic covers 17,18. Thereby, the outside air can be supplied directly into the saddle 15 and into the telescopic covers 17,18 even though the telescopic covers 17, 18 are provided. Thus, it is possible to make the sliding surface 13a of the column 13 in contact with the outside air sufficiently, and to keep the temperature of the space inside the telescopic covers 17, 18 equal to the temperature around the machine tool. As a result, thermal balances in a front-back direction and in a left-right direction of the column 13 can be kept constant, and heat deformation of the column 13 can therefore be suppressed. Thus, it is possible to maintain straightness at the time of sliding the saddle 15, and thereby to prevent deterioration in machining accuracy.
The structure for suppressing column heat deformation in a machine tool according to the present invention is, therefore, configured to supply the outside air, which is taken into the blower 30 installed on the upper surface of the column 13, along the sliding surface 13a of the column 13 through the air supply pipe 41, and then to jet the outside air out of the injection holes 41 therein into the saddle 15 and into the telescopic covers 17, 18. Thus, the structure is capable of suppressing the heat deformation of the column 13 without requiring large-scale installation work.
SECOND EMBODIMENT
Next, a second embodiment of the present invention will be described in detail by

using Fig. 3 and Fig. 4. Note that the same members as those described in the first embodiment will be designated by the same reference numerals, and a duplicate explanation will be omitted.
As shown in Fig. 3 and Fig. 4, a blower 30 and a terminal box 51 are installed on a floor surface F on the opposite side of a machine tool 1 from a main spindle 16 (a tool T), and terminal boxes 52, 53 are provided on a side surface of a column base 12 and on a side surface of a column 13. These terminal boxes 51 to 53 have a structure configured to discharge air which is supplied thereto.
A hose 54 is connected between the blower 30 and the terminal box 51. Meanwhile, a drag chain-type hose 55 is connected between the terminal boxes 51, 52 and a connection pipe 56 is connected between the terminal boxes 52, 53. Moreover, a hose 57 is connected between the terminal box 53 and the saddle 15. Note that the terminal boxes 51,52,53, the hoses 54,55,57, and the connection pipe 56 collectively constitute a saddle air supply channel.
Moreover, injection holes (saddle injection holes) 15b, 15c are formed in an upper surface and a lower surface of the saddle 15. The injection hole 15b communicates with the inside of an upper telescopic cover 17 while the injection hole 15c communicates with the inside of a lower telescopic cover 18. In addition, ends of the two-pronged hose 57 located inside the saddle 15 are connected to these injection holes 15b, 15c.
Accordingly, when the blower 30 is driven, the outside air around the machine tool 1 (the column 13) is taken into the blower 30, and is then jetted out of the injection holes 15b, 15c in the saddle 15 through the terminal boxes 51, 52, 53, the hoses 54, 55, 57 and the connection pipe 56, and supplied into the telescopic covers 17, 18. Thereafter, the outside air supplied into the telescopic covers 17, 18 is discharged from an upper opening of the upper telescopic cover 17, gaps between covers 17a to 17d, and gaps between covers 18a to 18d.

Moreover, the terminal boxes 52, 53 are connected to each other with the connection pipe 56 while the terminal box 53 and the saddle 15 are connected to each other with the hose 57. Accordingly, even when the column base 12 and the saddle 15 slide at the time of supplying the outside air, the connection pipe 56 and the hose 57 is capable of changing their curved states in response to their sliding positions. Thus the outside air which is taken in is smoothly supplied.
By this, the outside air can be supplied directly into the saddle 15 and into the telescopic covers 17,18 even though the telescopic covers 17,18 are provided. Thus, it is possible to make the sliding surface 13a of the column 13 in contact with the outside air sufficiently, and to keep the temperature of the space inside the telescopic covers 17, 18 equal to the temperature around the machine tool. As a result, thermal balances in a front-back direction and in a right-left direction of the column 13 can be kept constant, and heat deformation of the column 13 can therefore be suppressed. Thus, it is possible to maintain straightness at the time of sliding the saddle 15, and thereby to prevent the deterioration in machining accuracy.
The structure for suppressing column heat deformation in a machine tool according to the present invention, therefore, is configured to supply the outside air, which is taken into the blower 30 installed on the floor F, into the saddle 15 through the terminal boxes 51, 52, 53, the hoses 54,55,57 and the connection pipe 56, and then to jet the outside air out of the injection holes 15b, 15c therein into the telescopic covers 17, 18. Thus, the structure is capable of suppressing the heat deformation of the column 13 without requiring large-scale installation work.
It should be noted that although the above-described embodiments use the telescopic covers 17, 18 as the sliding surface covers, bellows covers may be used instead.

INDUSTRIAL APPLICABILITY
The present invention is applicable to inner surfaces of telescopic covers formed of multiple cover members which are mutually slidably stacked on one another, and to a telescopic cover device configured to remove foreign objects which may adhere to a sliding surface to be protected by the telescopic covers.

WE CLAIM:
1] A structure for suppressing column heat deformation in a machine tool, characterized by comprising:
a saddle configured to rotatably support a main spindle to which a tool is detachably attached;
a column including a sliding surface configured to slidably support the saddle; a sliding surface cover provided in such a manner as to cover the sliding surface and configured to expand and contract along with slide of the saddle; and air supplying means for supplying air to the inside of the sliding surface cover.
2] The structure for suppressing column heat deformation in a machine tool according to claim 1, characterized in that
the air supplying means comprises an intra-cover air supply channel extending along the sliding surface and penetrating the saddle, and
intra-cover injection holes communicating with the inside of the saddle and the inside of the sliding surface cover are formed in the intra-cover air supply channel.
3] The structure for suppressing column heat deformation in a machine tool according to claim 1, characterized in that
the air supplying means comprises a saddle air supply channel communicating with the inside of the saddle, and
a saddle injection hole connected to the saddle air supply channel and communicating with the inside of the sliding surface cover is formed in the saddle.