Claims:We claim:
1. A machine for filling capsules with powder, including a dosator comprising a horizontally disposed powder feed chamber having a feed screw horizontally extending in the feed chamber and rotatable about a horizontal axis, the feed chamber comprising a feed opening communicating with a powder feed hopper and a discharge opening connected to one end of a powder discharge tube, the other end of the powder discharge tube communicating with an open bottom powder tub located below the powder discharge tube, an ejector piston assembly disposed at one side of the powder tub externally of the powder tub and comprising a row of ejector pistons mounted in a piston support plate horizontally disposed for guided vertical up and down movement with the ejector pistons axially and a dosing assembly disposed at the open bottom of the powder tub, wherein the dosing assembly comprises a linearly movable dosing top plate disposed underneath the open bottom of the powder tub in sliding contact with the open bottom of the powder tub and a linearly movable bottom support plate, each of the top plate and bottom support plate having a leading edge and a trailing edge, the leading edge of the top plate extending over the leading edge of the bottom support plate in the direction of the said one side of the powder tub and having a row of dosage metering passages extending transversely therethrough and exposed at the open bottom of the powder tub and opening onto the bottom support plate, the dosage metering passages matching in position and layout with the ejector pistons and a differential drive means connected to the trailing edges of the top plate and bottom support plate and configured to move the top plate and bottom support plate together in the direction of the said one side of the powder tub with the dosages of powder in the dosage metering passages in the top plate beyond the powder tub and then to move the bottom support plate in the reverse direction to eject the dosages of powder in the dosage metering passages in the top plate followed by the top plate.

2. The machine as claimed in claim 1, wherein the top plate is guided in a top linear guide means and the bottom support plate is guided in a bottom linear guide means.

3. The machine as claimed in claim 2, wherein the top linear guide means and the bottom linear guide means each comprises a channel member mounted on the respective plates and slidably engaged over a linear rail fixed in position.

4. The machine as claimed in claim 1, wherein the differential drive means comprises a spindle rotatable about a vertical axis and a cam body mounted to the spindle and having a top cam groove at the top surface thereof and a bottom cam groove at the bottom surface thereof, a top cam follower engaged in the top cam groove and connected to the trailing edge of the top plate and a bottom cam follower disposed in the bottom cam groove and connected to the trailing edge of the bottom support plate, the trajectory and geometry of the top and bottom cam grooves being so profiled and configured as to move the top plate and bottom support plate together in the direction of the said one side of the powder tub and then to move the bottom support plate in the reverse direction followed by the top plate.

5. The machine as claimed in claim 1, wherein the ejector piston assembly comprises a vibrator connected to the piston support plate to vibrate the piston support plate and ejector pistons in the vertical plane in narrow amplitude range of 20 to 60 microns.

6. The machine as claimed in claim 5, wherein the vibrator is ultrasonic vibrator.

7. The machine as claimed in claim1, wherein the powder tub comprises a flexible material powder leveler blade disposed in the powder tub for oscillation in the vertical plane in a narrow angular range of -5 to 5°.

8. The machine as claimed in claim 7, wherein the flexible material powder leveler blade is fixed to a reversible motor shaft extending horizontally in the powder tub and disposed for oscillatory motion about a horizontal axis in a narrow angular range of -5 to 5° to oscillate the flexible material powder leveler blade in the narrow angular range of -5 to 5° in the vertical plane.

9. The machine as claimed in claim 1, wherein the powder tub comprises a flexible material skirt at the open bottom thereof extending down upto the top surface of the top plate.

10. The machine as claimed in claim 9, wherein the open bottom of the powder tub describes a gap with the top surface of the top plate and wherein the flexible material skirt extends down from the inner sidewall of the bottom surface of the powder tub upto the top surface of the top plate and has a reduced width as compared to the width of the sidewall of the powder tub at the bottom surface thereof.
, Description:FIELD OF THE INVENTION
This invention relates to a machine for filling capsules with powder.

BACKGROUND OF THE INVENTION
In the encapsulation industry, pharmaceutical industry in particular, pharmaceuticals and neutraceuticals and food supplements in powder form are often made into compact dosages by volumetric filling of the powder in capsules. This prevents spillage and wastage of the powder, helps to maintain uniformity of dosages of the powder and makes oral administration of the dosages easy and convenient.

A machine for filling capsules with powder, includes a capsule handling turret comprising a circular table disposed for rotation about a vertical axis intermittently at intervals and having a plurality of rows of capsule holding pockets radially equidistantly spaced from one another on a pitch circle at the circumference thereof. The circular table is configured to rotate about a plurality of stations including a capsule orienting and loading and separating station, a capsule body and capsule cap presence sensing station, a capsule body filling station, an unopen capsule ejection station, a filled capsule body closing station, a closed capsule ejection station and a capsule holding pockets cleaning station in a cycle of operation of the capsule handling turret.

The machine also includes a dosator located at the capsule body filling station for volumetric filling of a row of capsule bodies held in a row of capsule holding pockets with their mouths directed upwardly when positioned at the capsule body filling station during intermittent rotation of the circular table in a cycle of operation of the capsule holding turret.

The dosator comprises a horizontally disposed powder feed chamber having a feed screw horizontally extending in the feed chamber and rotatable about a horizontal axis. The feed chamber comprises a feed opening communicating with a powder feed hopper and a discharge opening connected to one end of a powder discharge tube. The other end of the powder discharge tube communicates with an open bottom powder tub located below the discharge tube.

The dosator further comprises a dosing assembly or mechanism at the open bottom of the powder tub consisting of a linearly movable dosing top plate disposed underneath the open bottom of the powder tub and having a leading edge and a trailing edge. The top plate is in sliding contact with the open bottom of the powder tub and a stationary bottom support plate. The top plate has a row of dosage metering passages transversely extending therethrough across the leading edge thereof and exposed at the open bottom of the powder tub and opening onto the bottom support plate. The dosage metering passages match with the capsule holding pockets in position and layout.

The dosator further comprises a drive mechanism consisting of a spindle disposed for rotation about a vertical axis and a cam body mounted to the spindle and having a cam groove at the upper surface of the cam body. A cam follower is disposed for rotation in the cam groove and connected to the trailing edge of the top plate to move the top plate forward in the direction of one side of the powder tub and back.

The dosator also comprises an ejector piston assembly disposed at the said one side of the powder tub externally of the powder tub. The piston assembly consists of a row of ejector pistons mounted in a horizontally disposed piston support plate which is disposed for guided vertical up and down movement with the pistons axially. The pistons match in position and layout with the row of dosage metering passages in the top plate. The pistons have narrow tips sized to enter the dosage metering passages in the top plate.

The dosage metering passages at the leading edge of the top plate are normally disposed within the powder tub for the powder to get filled in the dosage metering passages and form dosages of the powder. The trajectory and geometry of the cam groove is so profiled and configured that the cam follower causes the top plate to slide against the support plate and the bottom surface of the powder tub in the direction of the said one side of the powder tub with the dosage metering passages beyond the support plate and the powder tub and move back in the reverse direction to its original position in a cycle of operation of the capsule handling turret when the capsule bodies in a row of capsule holding pockets with their mouths directed upwards are positioned at the capsule body filling station.

The powder ejector pistons remain at their top position and the top plate remains at its reverse position with the dosage metering passages inside the open bottom powder tub until a row of capsule bodies with their mouths directed upwards index to the capsule body filling station. Powder in the powder tub being fed from the powder feed chamber enters the row of dosage metering passages in the top plate and form dosages of the powder. The dosages are retained in the dosage metering passages against the bottom support plate.

When a row of capsule bodies with their mouths directed upwards index to the capsule body filling station, the top plate moves in the direction of the said one side of the powder tub against the stationary bottom plate and the bottom surface of the powder tub with dosages of the powder in the dosage metering passages beyond the bottom support plate and the powder tub until the dosage metering passages are aligned with the capsule bodies with their mouths directed upwards positioned below the dosage metering passages. The ejector pistons move down and their tips enter the dosage metering passages in the top plate to push the dosages into the capsule bodies below. The ejector pistons move up and disengage from the dosage metering passages in the top plate and the top plate moves back in the reverse direction to its original position. The capsule handling turret continues to rotate intermittently to carry out further operations at the various subsequent stations thereof.

In such a machine, when the top plate with the dosage metering passages filled with dosages of powder slides against the bottom support plate and the bottom of the powder tub in the direction of the said one side of the powder tub, the powder in the dosage metering passages can get crushed and damaged between the top plate and the bottom support plate and the bottom of the powder tub due to friction between the two plates and between the top plate and the bottom of the powder tub. Besides, while the ejector pistons move up and down axially, the entire powder in the dosage metering passages may not be completely pushed down into the capsule bodies by the pistons, especially the powder particles stuck in the dosage metering passages. As a result, there can be weight and dosage variations. This is very critical, especially in the case of pharmaceuticals and microdosages of pharmaceuticals in particular. There will be also wastage of material and dust generation.

During the sliding movements of the top plate, the surface areas of contact between the top plate and the sidewall of the powder tub at the bottom surface thereof and between the top plate and support plate are very large. Therefore, the frictional forces developed are high. Due to the high friction between the top plate and bottom support plate and the sidewall of the powder tub at the bottom surface thereof, not only the wear and tear to the components will be high, but the sliding movements of the top plate also will be hampered thereby affecting the speed of operation of the dosator and increasing the power and energy requirement for operation of the dosator. Because of the high frictional forces, the movement of the top plate is also not smooth. Wear and tear also can cause weight and dosage variations in that the powder may not get uniformly filled in the dosage metering passages and the capsule bodies. It will also require the components to be replaced periodically.

While the powder is being discharged into the powder tub from the powder discharge chamber, there are chances for heap formation of the powder in the powder tub. Because of heap formation, the powder may not get uniformly filled in the dosage metering passages and the capsule bodies. This also will give rise to weight and dosage variations.

There is thus need for machines for filling capsules with powder, which obviate the problems and disadvantages in the prior art and which will help to fill the dosage metering passages and capsule bodies with uniform dosages of powder and which will prevent weight and dosage variations and wastage of material and dust generation and which will reduce frictional forces and associated problems and disadvantages and which will ensure smooth operation of the dosator.

DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a machine for filling capsules with powder, including a dosator comprising a horizontally disposed powder feed chamber having a feed screw horizontally extending in the feed chamber and rotatable about a horizontal axis, the feed chamber comprising a feed opening communicating with a powder feed hopper and a discharge opening connected to one end of a powder discharge tube, the other end of the powder discharge tube communicating with an open bottom powder tub located below the powder discharge tube, an ejector piston assembly disposed at one side of the powder tub externally of the powder tub and comprising a row of ejector pistons mounted in a piston support plate horizontally disposed for guided vertical up and down movement with the ejector pistons axially and a dosing assembly disposed at the open bottom of the powder tub, wherein the dosing assembly comprises a linearly movable dosing top plate disposed underneath the open bottom of the powder tub in sliding contact with the open bottom of the powder tub and a linearly movable bottom support plate, each of the top plate and bottom support plate having a leading edge and a trailing edge, the leading edge of the top plate extending over the leading edge of the bottom support plate in the direction of the said one side of the powder tub and having a row of dosage metering passages extending transversely therethrough and exposed at the open bottom of the powder tub and opening onto the bottom support plate, the dosage metering passages matching in position and layout with the ejector pistons and a differential drive means connected to the trailing edges of the top plate and bottom support plate and configured to move the top plate and bottom support plate together in the direction of the said one side of the powder tub with the dosages of powder in the dosage metering passages in the top plate and then to move the bottom support plate in the reverse direction to eject the dosages of powder in the dosage metering passages in the top plate followed by the top plate.

DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 is a schematic partly sectional view of the dosator of a machine for filling capsules with powder according to an embodiment of the invention;

Fig 2 is a schematic partly sectional view of the ejector piston assembly of the dosator of Fig 1 at one side of the powder tub;

Fig 3 is a schematic side view of the ejector piston assembly of Fig 2;

Fig 4 is a schematic plan view of the dosing top plate of the dosator of Fig 1;

Fig 5 is a schematic isometric view of the powder tub of the dosator of Fig 1;

Fig 6 is a schematic sectional view of the powder tub of Fig 5;

Fig 7 is a schematic partly sectional view of the dosator of Fig 1 including the top and bottom linear guide means;

Fig 8 is a schematic sectional view at A – A in Fig 7;

Fig 9 is a schematic plan view of the differential drive mechanism of the dosator of Fig 1; and

Figs 10a, 10b and 10c are different operative positions of the dosing assembly of the dosator of Fig 1.

DESCRIPTION OF EMBODIMENT OF THE INVENTION
A machine for filling capsules with powder (not shown) includes a dosator 1 as illustrated in Figs 1 to 10c of the accompanying drawings. The dosator comprises a horizontally disposed feed chamber 2 having a feed screw 3 horizontally extending in the feed chamber and rotatable about a horizontal axis X1 with electric motor 4 connected to the feed screw. The feed chamber comprises a feed opening 5 communicating with a powder feed hopper 6 and a discharge opening 7 connected to one end of a powder discharge tube 8. The other end of the powder discharge tube 8 communicates with an open bottom powder tub 9 located below the powder discharge tube (Fig 1).

An ejector piston assembly 10 is disposed at one side of the powder tub (piston side of the powder tub) externally of the powder tub 9. The piston assembly comprises a row of powder ejector pistons 11 mounted in a horizontally disposed piston support plate 12. The piston support plate is in thread engagement with a ball screw 13 coupled to the shaft 14 of a reversible electric motor 15 disposed for rotation about a vertical axis X2. The ball screw is rotatably held in a bush 16 mounted on the piston support plate (Figs 2 and 3). As the motor shaft rotates in opposite directions in the vertical plane, the ball screw 13 rotates with the motor shaft and the piston support plate with the bush and pistons move up and down axially about the ball screw 13 and the motor shaft 14. The up and down movement of the piston support plate with the bush and pistons are guided by vertical guides 17 mounted on the piston support plate and engaged in guide grooves 18 in the machine frame 19 and in the guide slot 20 for the bush in the machine frame (Figs 1, 2, 3, 4, 7, 10a, 10b, 10c).

A vibrator 21, preferably ultrasonic vibrator, capable of generating vibrations in the vertical plane in a narrow amplitude range of 20 to 60 microns is connected to the piston support plate. Therefore, during the up and down movement of the piston support plate with the pistons in the axial direction, the piston support plate and the pistons are also subjected to vibrations in the vertical plane in the narrow amplitude range of 20 to 60 microns. Sufficient clearances are provided in the guide grooves 18 and guide slot 20 for the guide rods 17 and the bush 16 to vibrate in the respective guide grooves and guide slot and allow vibration of the piston support plate and pistons in the narrow amplitude range.
A dosing assembly 22a is disposed at the open bottom of the powder tub 9. The dosing assembly consists of a linearly movable dosing top plate 22 disposed at the bottom of the powder tub and having a leading edge 23 and a trailing edge 24. The open bottom of the powder tub describes a gap 25 with the top surface of the top plate (Figs 3, 6, 10a, 10b, 10c). A flexible material skirt 26 extends down from the inner sidewall of the open bottom surface of the powder tub upto the top surface of the top plate. The flexible material skirt has a reduced or narrow width or thickness as compared to the width or thickness of the sidewall of the powder tub at the bottom surface thereof.

The top plate 22 is in sliding contact with the bottom of the skirt 26 extending down upto the top surface thereof and a linearly movable bottom support plate 27 at the bottom surface thereof. The bottom support plate has a leading edge 28 and a trailing edge 29. The leading edge 23 of the top plate 22 extends over the leading edge of the bottom support plate in the direction of the piston side of the powder tub. The top plate has a row of dosage metering passages 30 extending transversely through the top plate across the leading edge of the top plate and opening onto the bottom support plate. The dosage metering passages match in position and layout with the pistons and are exposed at the open bottom of the powder tub. The tips 11a of the pistons are narrow and are sized to enter the dosage metering passages 30 in the dosing top plate. (Figs 4, 10a, 10b, 10c)

31a is a differential drive mechanism consisting of a spindle 31 rotatably held about a vertical axis X3 with an electric motor 32. The spindle consists of a cam body 32a having a top cam groove 33 at the top surface thereof and a bottom cam groove 34 at the bottom surface thereof. A top cam follower 35 is engaged in the top cam groove and connected to the trailing edge 24of the top plate 22. A bottom cam follower 36 is disposed in the bottom cam groove and connected to the trailing edge 29 of the bottom support plate 27. The trajectory and geometry of the top and bottom cam grooves are profiled and configured to move the top plate and bottom plate together in the direction of the one side or piston side of the powder tub and to move the bottom support plate first in the reverse direction and then to move the top plate in the reverse in the sequential order during rotation of the spindle about the vertical axis X3.

The top plate has a channel member 37 mounted thereon and slidably engaged over a linear rail 38 fixed in position. The bottom support plate has a channel member 39 mounted thereon and slidably engaged over a linear rail 40 fixed in position. (Figs 7 and 8). During the movements of the top plate and bottom support plate in the direction of the one side of the powder tub and in the reverse direction, they are guided by the respective channel members slidably engaged over the respective linear rails.

A flexible material powder leveler blade 41 is fixed to the shaft 42 of a reversible motor 43 extending horizontally in the powder tub and disposed for oscillatory rotation or motion about a horizontal axis X4 within a narrow angular range of -5 to 5° so as to oscillate the flexible material powder leveler blade in the vertical plane in the narrow angular range in the powder tub. (Figs 1, 3, 5 and 6).

The dosator operates in synchronization with a capsule handling turret (not shown) of the machine comprising a circular table disposed for rotation about a vertical axis intermittently at intervals and having a plurality of rows of capsule holding pockets radially equidistantly spaced apart from one another on a pitch circle at the circumference thereof. The capsule holding pockets in the table match in position and layout with the dosage metering passages 30 in the top plate 22 and the pistons 11. The circular table is configured to rotate intermittently at intervals about a plurality stations including a capsule orienting and loading and separating station, a capsule body and capsule cap presence sensing station, a capsule body filling station, an unopen capsule ejection station, a filled capsule body closing station, a closed capsule ejection station and a capsule holding pockets cleaning station in a cycle of operation of the machine.

The capsule handling turret construction or design and its operation are known to a person skilled in the art. Illustration and further description of the capsule handling turret are not necessary for understanding the invention. Therefore, the capsule handling turret has not been illustrated and described in detail.

At the beginning of operation of the dosator in a cycle of operation of the capsule handling turret, the dosage metering passages 30 in the powder dispensing top plate 22 remain within the open bottom of the powder tub 9 filled with powder 44 and forming dosages of powder 44a against the bottom support plate 27 as shown in Fig 10a of the accompanying drawings. When a row of capsule bodies held in a row of capsule holding pockets of the capsule handling turret with their mouths directed upwardly reach the capsule body filling station, the powder dispensing top plate 22 with the dosage metering passages 30 disposed within the open bottom powder tub and formed with dosages of powder 44a move in the direction of the one side or piston side of the powder tub alongwith and in unison with the bottom support plate beyond the powder tub until the row of dosage metering passages in the top plate are aligned with the tips 11a of the ejector pistons 11.

During the movement of the top and bottom plates 22 and 27 together in the direction of the piston side of the powder tub, the dosage metering passages 30 are closed at the bottom against the bottom support plate 27. Therefore, the dosages of powder 44a in the dosage metering passages continue to remain intact in the dosage metering passages. At the same time there is no relative movement and friction between the top plate 22 and bottom support plate 27. The bottom support plate moves back to its original position as shown in Fig 10b of the accompanying drawings exposing the dosages of powder in the dosage metering passages at the bottom thereof. The pistons 11 move down and their tips 11a enter the dosage metering passages and push down the dosages of powder in the dosage metering passages into the respective capsule bodies 45 aligned underneath the dosage metering passages.

The ejector pistons 11 move up and disengage from the dosage metering passages 30 in the top plate 22 and the top plate moves back to its original position. The capsule handling turret continues to rotate or index intermittently to carry out further operations at the various subsequent stations thereof.

As the piston support plate with the pistons move up and down axially, they are also subjected to vibrations in the vertical plane in the narrow amplitude range of 20 to 60 microns. Therefore, powder particles stuck in the dosage metering passages 30 are dislodged and pushed down into the capsule bodies.

The flexible material powder leveler blade 41 oscillates in the vertical plane in the narrow angular range of -5 to 5° in the powder tub 9 to prevent heap formation of powder in the powder tub being fed into the powder tub from the powder feed chamber 2 and to level up the powder in the powder tub and maintain a powder bed of uniform thickness in the powder tub. Because of the uniform powder bed in the powder tub, powder gets filled in the dosage metering passages 30 in the top plate 22 uniformly to form uniform dosages.

The material thickness of the flexible material skirt 26 is narrow and reduced as compared to the sidewall of the powder tub at the bottom thereof. Therefore, the surface area of the flexible material skirt in contact with the top surface of the top plate is correspondingly narrow and reduced. Because of the reduced contact surface and because of the flexible nature of the skirt, the skirt offers negligible friction to the movement of the dosing top plate. It folds and bends against the top surface of the top plate to prevent leakage of powder from the powder tub and at the same time prevent crushing and damage to the powder.

The flexible material skirt 26 is optional and in the absence whereof the dosing top plate 22 closes against the open bottom of the powder tub 9 in sliding contact therewith to facilitate movement of the top plate and to prevent leakage of the powder. Besides being a double cam groove and double cam follower drive, the differential drive means or mechanism of the invention can be of other configuration and construction. The top linear guide means and the bottom linear guide means can be of other construction and configuration. The flexible material powder leveler blade is optional and can be of other construction and configuration. The vibrator is optional and can be also mechanical, pneumatic or electric vibrator. Such variations in the construction and configuration of the invention should be construed and understood to be within the scope of the invention.

According to the invention during the movement of the dosing top plate with powder filled in the dosage metering passages therein in the direction of the piston side of the powder tub, the bottom support plate also moves together with the top plate in unison. Therefore, there is no friction between the top plate and bottom support plate in their movement in the direction of the piston side of the powder tub. As a result, chances of the powder getting crushed and damaged between the top plate and bottom support plate are completely eliminated. Because of this weight and dosage variations are eliminated. Wastage of material and dust generation are also eliminated.

During the upward and downward movement of the pistons axially, the pistons are being vibrated in the vertical plane in a narrow amplitude range. Therefore, powder particles stuck in the dosage metering passages get dislodged and fall down into the capsule bodies. Because of this also weight and dosage variations are eliminated.

Due to the oscillation of the flexible material powder leveler blade in the powder tub in the vertical plane in a narrow angular range, powder being discharged into the powder tub from the discharge chamber gets levelled up in the powder tub. As a result, heap formation is prevented and a powder bed of uniform thickness is formed in the powder tub. This ensures uniform filling of powder in the dosage metering passages in the top plate thereby eliminating dosage and weight variations.

The flexible material skirt at the bottom of the powder tub has a narrow or reduced thickness or width as compared to the thickness or width of the surface area of the sidewall of the powder tub at the bottom thereof. Therefore, the surface area of contact between the skirt and the top plate is substantially reduced. The narrow flexible in contact with the top surface of the dosing top plate does not practically offer any friction to the movement of the top plate underneath. Being flexible, it folds and bends against the top plate to prevent powder escaping the powder tub and at the same time does not crush or damage the powder.

Since the leading edge 23 of the dosing top plate 22 is extending over the leading edge 28 of the bottom support plate 27 and has the dosage metering passages 30 opening onto the leading edge of the bottom support plate, the top plate has to travel underneath the powder tub against the bottom support plate, only by a short distance to move out of the powder tub and move into the powder tub. Therefore, the frictional forces between the open bottom of the powder tub and the bottom support plate even in the absence of the flexible material skirt will be minimal.

In the dosator of the invention, there is no relative movement between the top plate and bottom plate during their movement together in the direction of the piston side of the powder tub. Both the bottom support plate and top plate are moved back independently and sequentially. There is only a limited or short travel of the top plate and bottom support plate in the reverse movement as the leading edge of the top plate extends over the leading edge of the bottom support plate. Because of all this, the powder does not get trapped between the plates, frictional forces developed during operation of the dosator are reduced and stresses and strains on the components or parts are reduced, operation of the dosator is smooth, wear and tear to the components is reduced, periodicity of replacement of the components is reduced, cost is reduced, power requirement is reduced and weight and dosage variations resulting from wear and tear are reduced.