US2997741A - Rotary compacting machines - Google Patents

Description

Aug. 29, 1961 J. CROSSLEY 2,997,741

ROTARY COMPACTING MACHINES Filed Jan. 20, 1959 4 Sheets-Sheet 1 Figl.

Inventor (/aZ fivwy By 7444/ 71 Attorneys 1961 J. CROSSLEY 2,997,741

ROTARY COMPACTING MACHINES Filed Jan.,20, 1959 4 Sheets-Sheet 2 Inventor lfio fiwtay By ,fmr 7a A ttomey;

Aug. 29, 1961 J. CROSSLEY 2,997,741

ROTARY COMPACTING MACHINES Filed Jan. 20, 1959 4 Sheets-Sheet 3 lnvenfur By 7 /7 u A ftorneys Aug. 29, 1961 J. CROSSLEY 2,997,741

ROTARY COMPACTING MACHINES Filed Jan. 20, 1959 4 Sheets-Sheet 4 e66 Fig. 4

Inventor (/aa frwzavy B y 7% 7% A ttorneyy 2,997,741 ROTARY COMPACTING MACHINES Jack Crossley, Rochdale, England, assignor to John Holroyd & Company Limited, Rochdale, England Filed Jan. 20, 1959, Ser. No. 737,997 3 Claims. (Cl. 1820) This invention concerns rotary compacting machines of the type including a rotary die table having one or more dies therein and, associated each die, upper and bottom punches which upon rotation of the table, engage pressure rolls and are caused thereby to enter into the dies and to compress material in the dies. Such machines (which hereinafter will be referred to as compacting machines of the type described) are employed, for example, in the manufacture of pharmaceutical tablets from powdered medicinal ingredients, or for making metal and ceramic articles, and like purposes.

Hitherto, it has been usual to mount one of the two rolls stationarily on the machine and, as a safety measure against overloading, to mount the second roll, again on the machine, so as to be displaceable when a predetermined loading is exceeded, so as to prevent damage to the machine.

Certain disadvantages arise out of this prior roll arrangement. Firstly, the machine itself has to be constructed so as to withstand the pressures resulting from engagement of the rolls with the punches both during normal compression and when overloading occurs. In practice, considerable stresses are developed, and machines of even robust construction vibrate considerably during use. Secondly, the mounting of one roll so as to be displaceable safe-guards eifectively only against the event that an overloading occurs requiring one only of the punches to be relieved of pressure. Thus, if the roll associated with the bottom punch is displaceable, an overloading requiring relieving movement of the upper punch may occur, and this is not allowed for since the roll associated therewith is stationary, and damage to the machine could occur. Thirdly, where one roll is stationary and the other is movable, defective compacted articles (eg. tablets) can be produced. This is because such articles are usually made from powdered materials, and such materials do not readily transmit stresses applied thereto, and with the arrangement such as has been described the resulting articles are unevenly compacted and compressed, and parts thereof are liable to crumble very easily, particularly when deep filling.

It is an object of this invention to provide a machine wherein the disadvantages arising from making one roll only displaceable are eliminated, and which enables, if desired, the rolls to be mounted in such a manner that substantially no stresses therefrom are transmitted to the rest of the machine.

According to the present invention a compacting machine of the type described is characterised in that the pressure rolls associated with both the lower and upper punches are displaceable when a predetermined loading is exceeded.

Such arrangement permits displacement of either or both rolls when overloading occurs and consequently guards fully against damage to the machine and tools whilst at the same time ensuring that firmly and evenly compressed articles are produced.

To relieve the machine of stresses from pressure applied by the rolls, the arrangement aforesaid is preferably further characterised in that the two rolls are suitably mounted on and coupled together by a framework or the like substantially independent of the rest of the machine, and which resist separation of the rolls except when a predetermined load occurs at the rolls.

Preferably such framework or the like includes a pair assists Patented Aug. 29, 196i of roll mountings which are pivoted with respect to one another and connected by tie means which normally resists separation of the rolls, such tie means including a hydraulic accumulator which can be preset to a predetermined load and which will permit separation of the rolls when such load is exceeded.

The invention will be described further, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a side elevation of a preferred embodiment of machine according to the present invention,

FIG. 2 is a cross-sectional side elevation of the machine of FIG. 1, the section being taken approximately on line IIII of FIG. 4,

FIG. 3 is a cross-sectional side elevation similar to FIG. 2, but taken on the line III-III of FIG. 4,

FIG. 4 is a cross-sectional plan view of the machine, taken on the line IV-IV of FIGS. 2, and 5,

FIG. 5 is a detached elevation showing part of the mechanism of the machine.

In the various figures, certain parts of the machine have been omitted, for the sake of clarity.

The machine illustrated comprises a frame it) supporting a horizontal bed 11 whereon is mounted a stationary central vertical pillar i2. Journalled on this pillar 12, by bearings 13, is a rotatable die table 14 having a flat portion 15 wherein dies 16 are located at regular intervals.

Means for rotating the die table 14 comprises a vertical shaft 17 extending through the bed 11 and journalled in a housing 13, 19, 20 supported from the horizontal bed 11, a gear wheel 21 on the shaft 17 meshing with a toothed annulus 22 secured to the underside of the die table 14 by bolts 23. A worm wheel 24 is secured to the shaft 17 within the housing part 19 and this meshes with a worm (not visible) mounted on a drive shaft 25 to which a pulley wheel 26 is secured. .T'he pulley wheel 26 is belt driven from a layshaft which in turn is belt driven from an electric motor (not shown).

The die table 14 is thickened at 27 and such thickened part accommodates vertically slidable lower punches 28, one punch 28 being provided for each die 16. Upward and downward movement of the punches 28 other than compressive movement thereof is controlled by engagement with heads 29 of the punches with the surface of the bed 11 or with adjustable cam tracks 3% secured to the bed 11. As can be seen at the left-hand side of FIG. 2, the underside of the cam track St} is inclined and rests upon a wedge shaped thrust bar 31 which is displaceable by a screw 32 rotatable by a knob 33 to raise and lower the cam track 30.

The die table 14 is also provided with an upper flange 34, and this provides a mounting for upper punches 35, one being aligned with each die 16. Each upper punch 35 has a head 36 co-operating with a cam track 37 mounted stationarily on the pillar 12, the cam track 37 serving to raise and lower the punches 35 except when compressive forces are applied thereto.

Various feed means can be provided for feeding pulverulent or granular material to the fiat part 15 of the die table 14. The means described comprises a pair of feed hoppers 38 disposed at diametrically opposed positions relative to the table 14 upon adjustable supports 3811. Each hopper 38 has a chute 39 whereby the material is fed to filling shoes 4% adjustably mounted upon pillars 4-1 on the bed 11 so as to touch lightly onto the flat part 15 of the die table 14. Thus, as the table 14 rotates, the dies 16 pass, in turn, under the filling shoes 40, and will receive material therefrom, the lower punches 28 being lowered for this purpose.

Mounted on the upper end of the pillar 12 by a boss 42 is a crosshead 43 having an integral outer casing 44 v) and a detachable cover 45. This crosshead 43 serves as a mounting for a pair of pressure roll assemblies which serve, as the die table 14 rotates, to press the upper and lower punches 35, 28 of the dies 16 towards one another to compact or compress material in the dies 16. Since the two pressure roll assemblies are substantially iden tical, one only thereof will be described, and the reference numerals employed will be given the suffix a. For identification purposes, the corresponding parts of the other assembly have been given similar reference numerals in the drawings, but with the sufiix b, but such reference numerals are not referred to in detail in the text, it being understood that a part having a suffix b in the said other assembly is identical to the corresponding part having suffix a in the described assembly.

Secured into the crosshead 43 is a heavy horizontal pivot pin 46a to which is pivoted an upper roll mounting comprising a pair of adjacent metal plates 47a connected by webs 48a and supporting a horizontal upper pressure roll shaft 49a whereon an upper pressure roll 59a is rotatably mounted with its axis horizontal and radial- 1y disposed relative to the pillar 12. The pivot pin 46a is arranged at one end of the plates 47a, so that the latter are capable of swinging up and down relative to a roughly horizontal position.

At their ends remote from the pivot pin 46a, a pin 51a passes horizontally through the plates 47a and an eye 52a provided on a vertical rod 53a which extends upwards through a stationary support plate 5411 which is integral with or mounted in the casing 44. The upper end of the rod 53a is screw threaded and a hand wheel 55a threadedly located thereon from outside the cover 45 engages the support plate 54a.

Also mounted upon the pivot pin 46a is a depending connecting rod 56a and this serves to connect a lower pressure roll mounting to the upper pressure roll mounting just described. The lower pressure roll mounting comprises a pair of adjacent plates 57a connected by Webs 58a and pivotally mounted at one end on the connecting rod 56a by a pivot pin A lower pressure roll shaft 60a is supported by the plates 57a and a lower pressure roll 61a is mounted thereon so as to be disposed in alignment below the upper pressure roll 50a.

Pins 62a extend through the plates 57a and serve to connect the ends of the plates 57a remote from the pivot pin 59a with a bracket 63a provided upon a hydraulic cylinder 64a. The cylinder 64a houses a slidable piston 65a which is held captive by an end plug 66a in the cylinder, this end plug 66a defining the lowermost position of the piston 65a.

Connecting the piston 65a and the rod 53a is a tension rod 67a, this being secured to the piston by a nut 68a and extending through a suitable clearance in the bracket 63a. The rod 53a is screwed at its lower end and is provided with a locknut 69a which holds an externally threaded retaining nut 79a is provided with external serrations and is screwed and fixed into the adjusting sleeve nut 71a on the upper end of the tension rod 67a The elfective length of the rod 53a and tension rod 67a, and consequently the relative position of the lower roll 61a can be adjusted by screwing the adjusting sleeve nut 71a on or off the tension rod 67a, a spring finger 72a engaging the serrations on the retaining nut 70a to prevent unintentional rotation thereof of sleeve nut 71a.

Rotation of the hand wheel 55a raises or lowers through the tension rod assembly 53a67a71a, the pressure rolls 50a and 61a, by raising or lowering the pressure roll shafts 49a and 60a relative to their pivot pins 46a and 5% respectively. This adjustment maintains the preset distance between the tips of the punches 28 and 35, but enables the entry of the tips of the punches 28 and 35 to be altered in relation to the die 16.

The hydraulic cylinder 64a is connected, by a flexible tube 73a to a pre-loading device comprising a cylinder 74a (to which the tube 73a is connected) and a piston 75:: which is loaded by a heavy compression spring 76a. The pre-loading cylinder 74a is connected to a bracket 77a in the frame 10 and a tubular casing 78a which is secured to the cylinder 74a and encloses the compression spring 7511 has an end cap 79a engaging a second bracket 80a in the frame ltl whereby the device is located in the machine frame.

The operation of the machine will now be described.

As two feed means for feeding pulverulent or granular material and two sets of upper and lower pressure rolls are provided, the machine will serve to fill each die 16 and to compress the material therein twice upon each revolution of the die table 16. The following description explains the operations occurring as one die is moved when the die table 14 performs a half revolution it being understood that these operations are repeated in relation to the same die as the die table 14 performs a subsequent half revolution, and that the operations occur for each die 16 in succession.

Assuming the die 16 to be empty and approaching a filling shoe 40, the cam track 37 raises the upper punch 35 and the lower punch 28 rests by its head 29 upon the bed 11 so that it is in its lowermost position. The die, as it passes under the shoe 40 receives material from the shoe 4% and is filled therewith.

From this point the lower punch 28, supported by its head 29, passes onto the cam track 30 which can be adjusted by wedge 31 to bring the punch up in the die 16 to a predetermined position when excess material can be ejected out of the die 16 back into the filling shoe 40. The lower punch then returns to its lowest position, taking with it the material remaining in the die.

Thereafter, the cam track 37 causes the upper punch 35 to be lowered onto the material in the die 16, and the table continues to rotate, moving the die 16 and punches 35, 28 so that these punches pass between the upper and lower pressure rolls 50a, 61a, engaging with the latter by their heads 36, 29 respectively. Therefore, the rolls 50a, 61a act to force the upper and lower punches 35, 28 towards each other under pressure as defined by the pressure prevailing in the hydraulic cylinder 64a, to compress the material in the die 16 to the form of a tablet or the like.

After the die 16 and punches 35, 28 have passed the pressure rolls, the cam track 37 acts to raise the upper punch 35 completely clear of the die 16, whereafter the lower punch 23 engages a cam track 30 which acts to raise the lower punch 28 so that the compressed tablet or the like is brought flush with the flat part 15 of the die table 14.

Continued movement of the die table causes the tablet to engage an inclined guide (not shown) which deflects the tablet laterally outwards of the die table 14, to fall into a delivery slide 81 (see FIG. 2). As the die 16 now passes from the inclined guide towards the second feed shoe 40, the cam track 30 lowers the lower punch 28 to its lowermost position, and when the die 16 reaches the second feed shoe 4% the sequence of operations just described is recommenced.

Whilst the pressure roll frameworks constituted by the connecting rods 561. 56b tension rods 67a and 67b and the roll mountings are pivotally connected to the crosshead each at one side and are suspended from the crosshead by the hand wheels 55a, 5511 on the other side, such connection is not such that stresses arising from normal or abnormal loading of the punches 35, 28 will be transmitted to the machine. Any stresses which do occur are confined to the framework, the rolls and the punches, and the framework is substantially an isolated unit independent of the machine frame or bed.

Under normal loading of the punches, the frameworks, under the influence of the hydraulic cylinders, act to resist any separational movement of the rolls and their mountings. However, should overloading occur, the pistons or the cylinders can move to permit either or both roll mountings to move, thus relieving overload from either or both punches.

It will be apprecated that the arrangement aforesaid is effective for minimising stresses which arise in the frame or body of the machine due to punch operation, and consequently machines according to the invention can be constructed less robustly than was necessary hitherto. Moreover, damage due to overloading a punch whose roll is not displaceable is completely avoided.

The invention is not confined to the precise details of the foregoing example and variations may be made thereto if desired. For example, the framework may be of any suitable form enabling a hydraulic cylinder and accumulator or like means to be employed to resist separation of the rolls until a predetermined loading occurs. Pneumatic, spring or other means may be incorporated into the apparatus in place of a hydraulic arrangement.

I claim:

1. In a rotary compacting machine including in combination, a machine frame, a rotary die table having a plurality of dies therein, an upper and lower punch associated with each of said dies and displaceable to enter said dies, a floating framework suspended from said machine frame comprising, upper and lower pressure roll mountings pivotally placed respectively above and below said die table, primary tie means suspended from said machine frame coupling together one end of each of said pressure roll mountings so as to resist separating displacement thereof, secondary tie means coupling the opposite ends of said pressure roll mounting so as to oppose separating displacement thereof except when a predetermined punch load is exceeded, and upper and lower pressure rolls carried within said floating framework by said pivotal mountings so as to be disposed in the path of and adapted to be engaged respectively byl said upper and lower punches to cause displacement of said punches into said dies whereby material in said dies is compacted.

2. A rotary compacting machine as set forth in claim 1 and including a pillar, a rotary die table rotatable around said pillar, and a crosshead on said pillar with said upper pressure roll mounting connected to said cross head so as to be disposed above said die table.

3. In a rotary compacting machine comprising in com bination, a machine frame, a pillar, a rotary die table rotatable around said pillar, a plurality of dies in said die table, upper and lower punches associated with said dies and displaceable to' enter into said dies, a crosshead on said pillar, a floating framework suspended from said machine frame comprising, an upper pressure roll mounting connected to said crosshead and disposed above said die table, a lower pressure roll mounting pivotally disposed below said die table, primary tie means suspended from said machine frame coupling one end of said lower pressure roll mounting with the corresponding end of said upper pressure roll mounting so as to prevent separating displacement thereof, secondary tie means depending from said crosshead and coupling the opposite ends of said pressure mountings, and upper and lower pressure rolls carried respectively by said pressure roll mountings so as to be disposed in the paths of and adapted to be engaged repectively by said upper and lower punches to cause displacement of said punches into their respective dies whereby material in said dies is compacted, said secondary tie means being adjustable to vary the spacing between said pressure rolls and the vertical positions thereof relative to said crosshead.

References Cited in the file of this patent UNITED STATES PATENTS 2,027,915 KUX Jan. 14, 1936 2,815,531 Stewart Dec. 10, 1957 2,846,723 Frank Aug. 12, 1958 FOREIGN PATENTS 69,829 Holland Apr. 15, 1952

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