GB2035154A - Loading means for automatic lathes - Google Patents

Abstract

An automatic capstan lathe is equipped with apparatus for loading components comprising a gripping assembly 18 mounted on one of the stations 14 of the capstan 10 and a magazine in the form of a circular disc 20 or a linear plate mounted for rotation about its axis or linear movement which is set perpendicular to the axis of the capstan 10. The disc 20 or plate has a row of uniformly spaced holes 22 disposed adjacent to its periphery. Each hole 22 contains a bush 24 in which a component 28 can be mounted. The magazine is indexed, under the control of the automatic control means for the lathe to successively bring each component 28 into alignment with the gripping assembly 18 on the capstan which then transferes it to the collet or chuck of the lathe. The gripping assembly 18 has three pivoting jaws 46 frictionally holding the component 28 against a buffer 42. Jaw friction is greater than bush friction but less than collet or chuck holding force. Jaw spacing is adjusted by screws 56 against a spring biassed core 52. <IMAGE>

Description

SPECIFICATION Loading means for automatic lathes This invention relates to loading means for automatic lathes and more particularly to means for loading individual components into automatic capstan lathes, which term is used herein to include turret lathes and multi-spindle automatic lathes.

It has already been proposed to use hopper feed arrangements for feeding components to a position from which they can be located, one after another to the chuck or collet of an automatic lathe. However, it has been found in practice that difficulties are encountered with such feed arrangements if the components do not have uniformly cylindrical outer surfaces. Moreover, a single misaligned component in the hopper can obstruct all subsequent feeding. Consequently, when individual components have to be loaded into an automatic lathe, the operation is frequently performed by hand. This means that automatic operation must be interrupted on completion of each cycle while the operator inserts a fresh component. Consequently such a machine requires frequent attention by an operator, most of whose time is unoccupied.

According to the invention in one aspect, apparatus for loading components into an automatic capstan lathe comprises a magazine having a series of component locations each adapted to contain a component, a component gripping assembly adapted to be mounted on one of the stations of the capstan of the lathe by reciprocable mounting means, and means for indexing the magazine to bring each component location in turn into alignment with the gripping assembly when the capstan is in a predetermied orientation.

According to the invention in another aspect, automatic lathe apparatus comprises a chuck or collet, a capstan, control means for sequentially generating control signals for controlling operations of the lathe, a component gripping assembly, reciprocable mounting means mounting the component gripping assembly on one of the stations of the capstan for radial reciprocating movement in response to the control signals from the control means, a magazine having a series of component locations, each adapted to contain a component, mounted so as to confront the capstan, and indexing means operative in response to control signals from the control means for sucessively bringing each component location into alignment with the component gripping assembly when the capstan is in a predetermined orientation.

According to the invention in a further aspect, a method of loading components into an automatic capstan lathe comprises loading the components into a magazine having a series of component locations for receiving such components, locating the magazine in alignment with the capstan of the lathe, and successively and sequentially carrying out the steps of rotating the capstan to bring component gripping means mounted on one station thereof into alignment with one of the component locations of the magazine, moving the gripping means into engagement with the component in said component location, withdrawing the gripping means with said component gripped thereby, rotating the capstan to bring the component gripping means into alignment with the chuck or collet of the lathe, advancing the gripping means to insert the component into the chuck or collet and withdrawing the gripping means, the magazine being indexed to bring another component location into alignment with the capstan between withdrawal of each component and advance of the gripping means to engage with a subsequent component.

The magazine is preferably a rotary magazine with the component locations arranged in a continuous path. The magazine may comprise a disc mounted for rotation about its centre with the component locations comprising respective holes uniformly spaced around the centre of the disc at a constant distance therefrom.

According to the invention in yet a further aspect, a component gripping assembly comprises a thrust member having a conical outer surface slidably mounted on a central support member, at least two layers spaced around the central support member and mounted for pivotal movement about axes forming a tangent to a circle centred on the axis of the thrust member and each having one end resting on the conical surface thereof, spring means for biasing the thrust member along the central member so as to force said one ends of the levers apart and stop means for limiting outward movement of said one ends of the levers, the other ends of the levers forming jaws for gripping a component inserted therebetween. Such a gripping assembly can conveniently be used in apparatus in accordance with the invention for loading an automatic lathe.

The stop means for limiting outward movement of the levers may be adjustable. In addition, adjustable buffer means may be mounted on the central support member for limiting the maximum extent of insertion of a component between the jaws.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic plan view of the capstan of an automatic capstan lathe together with loading apparatus in accordance with the invention, Figure 2 is a cross-sectional view taken on the line Il-Il of Fig. 1, and Figure 3 is a partially broken away eleva tional view of the magazine of the apparatus shown in Fig. 1.

Fig. 1 shows the disposition of loading apparatus 8 in accordance with the invention relative to the capstan 10 of an automatic lathe, the direction from which the capstan 10 confronts the chuck or collet of the lathe (not shown) being indicated by an arrow A.

Referring to Fig. 2, the capstan 10 has a double-acting pneumatic ram 12 mounted on one of its stations 14 so that the piston 16 of the ram 12 moves radially with respect to the capstan 10. A component gripping assembly 18 is mounted on the end of the piston 1 6.

The loading apparatus 8 comprises a magazine in the form of a disc 20 disposed confronting the gripping assembly 18. As can best be seen from Figs. 2 and 3, the disc 20, which is journalled on to a shaft 21, has a series of holes 22 of equal size uniformly spaced along a circular path adjacent to the periphery of the disc 20. The shaft 22 is mounted on a pillar (not shown) which may be secured to the bed of the lathe or mounted on a separate stand. Each of the holes 22 contains a respective bush 24 having a central bore 26 of appropriate dimensions to receive a component 28 which is to be loaded into the lathe. Each bush 24 has a flange 30 on the side facing the gripping assembly 18 and is contained in the disc by two O-rings 32 and 34, the O-ring 32 engaging between the flange 30 and the disc 20 and the O-ring 34 engaging with the other side of the disc 20.

The gripping assembly 18 comprises a hollow cylindrical housing closed at the end nearer to the capstan 10 and containing a central support member 40. A tapped hole, extending axially through the support member 40, has the piston 16 screwed into one end and a buffer member 42 screwed into the other. The extent of projection of the buffer member 42 can be adjusted by rotating it relative to the support member 40 and it can be secured in a required position by a conical lock-screw 44.

Three levers 46, 48 and 50 are pivotably mounted on respective extensions projecting from the open end of the cylindrical housing so that their outer ends form jaws surrounding the buffer member 42. The inner end of the levers 40 rest on a conical member 52 which is slidably mounted on the central support member 40 and biased outwardly by means of a spring 54. Respective adjustment screws 56, 58 and 60 are provided to limit outward movement of the inner end of each of the levers 46, 48 and 50 and thus limit the extent of closures of the jaws formed on the outer ends thereof.

In use, the adjustment screws 56, 58 and 60 are set so that the jaws on the outer ends of the levers 46, 48 and 50 are a light interference fit on the part of the component 28 which projects from the bushes 22 so as to grip it with a stronger frictional force than is exerted by the bush 24 but a smaller force than is exerted by the chuck or collet.

Means (not shown) are provided for rotating the disc 20 in angular steps equal to the angular separation between adjacent holes 22 so as to bring each hole in turn into alignment with the gripping assembly 18. For example, such means may comprise ratchet teeth formed on the wheel, the angular pitch of each tooth being equal to the aforesaid angular separation between adjacent holes 22, together with a pawl attached to the piston of a pneumatic ram.

In use, the disc 20 is positioned in alignment with the gripping assembly 18 when the capstan is in the position shown in Fig. 1. Bushes 24 of the appropriate size and shape for the components to be handled are fitted into the holes 22 in the disc 20 and loaded with components. Each operating cycle of the lathe, under control of the automatic controller thereof, includes the step of advancing the piston 16 of the ram 12, when the capstan 14 is in the position shown in Fig. 1, so that the component 28 in the bush 24 comes into contact with the buffer member 42 and is gripped by the jaws on the levers 46. The O-ringes 32 and 34 prevent transmission of the resulting shock to the disc 20, which shock could otherwise cause components to be shaken out of the other bushes.

The piston 16 is then retracted with a component 28 held in the gripping assembly 18. As the preceding component is ejected from the chuck or collet of the lathe, the capstan 14 is rotated to bring the gripping assembly 18 into alignment therewith, whereupon the piston 16 is again advanced to insert the component into the chuck or collet. On subsequent withdrawal of the capstan 16, the component 28 is retained by the chuck or collet of the lathe and is thus pulled out of the gripping assembly 18. Subsequently, at some convenient time during the cycle, the capstan is further rotated to bring the gripping assembly back into alignment with the disc 20 and the latter is indexed by one step to bring the next component 28 into alignment with the gripping assembly 18. The cycle then repeats.

When a number of components have been withdrawn from the magazine, fresh components are inserted by the operator.

Controllers of automatic lathes commonly provide pneumatic outputs which can be used directly to activate the ram 12 and the indexing mechanism for the disc 20. If such pneumatic outputs are not available, appropriate transducers must be provided.

The rotary magazine formed by the disc 20 may be replaced by a linear magazine. If such a linear magazine is formed in sections which are adapted to be fed through the machine sequentially, one such section may be removed from the machine for loading while another is being fed through the machine.

A lathe fitted with loading apparatus in accordance with the invention requires the attention of an operator for a relatively small number of relatively long periods of time as compared with a conventional automatic lathe. For example, while a conventional lathe may require an operator's attention for a few seconds at one minute intervals, a lathe fitted with a loading device in accordance with the invention may require an operator's attention for a single period of several minutes' duration every half hour or hour.

Claims (19)

1. Apparatus for loading components into an automatic capstan lathe comprising a magazine having a series of component locations each adapted to contain a component, a component gripping assembly adapted to be mounted on one of the stations for the capstan of the lathe by reciprocable mounting means, and means for indexing the magazine into alignment with the gripping assembly when the capstan is in a predetermined orientation.

2. Automatic lathe apparatus comprising a chuck or collet, a capstan, control means for sequentially generating control signals for controlling operations of the lathe, a component gripping assembly, reciprocable mounting means mounting the component gripping assembly on one of the stations of the capstan for radial reciprocating movement in response to the control signals from the control means, a magazine having a series of component locations, each adapted to contain a component, mounted so as to confront the capstan, and indexing means operative in response to control signals from the control means for successively bring each component location into alignment with the component gripping assembly when the capstan is in a predetermined orientation.

3. Aparatus according to claim 1 or 2, wherein the magazine comprises a circular disc mounted for rotation about its axis, the components location comprising a series of holes uniformly spaced along a circular path adjacent to the periphery of the disc.

4. Apparatus according to claim 1 or 2, wherein the magazine comprises a linearly movable body, the component locations comprising a series of uniformly spaced holes along a path parallel to the direction of linear movement thereof.

5. Apparatus according to claim 3 or 4, wherein each component location comprises a bush inserted into the corresponding hole in the disc and having a central bore dimensioned to receive a component to be loaded into the lathe.

6. Apparatus according to claim 5, wherein the bushes are resiliently mounted in the holes in the disc.

7. Apparatus according to claim 6, wherein each bush is secured to the disc by a pair of O-rings, one on each side of the disc.

8. Apparatus according to any preceding claim, wherein the gripping assembly comprises at least three jaws radially movable relative to the axis of reciprocating movement thereof and resiliently bias into their closed position, adjustable means for limiting the minimum spacing of the jaws and a buffer member for limiting the maximum extent of insertion of a component between the jaws.

9. Apparatus according to claim 8, wherein the buffer member is movable relative to the jaws in a direction parallel to the direction of reciprocating movement.

10. Apparatus according to any preceding claim, wherein the gripping assembly is mounted on a double-acting pneumatic ram.

11. A method of loading components into an automatic capstan lathe comprising loading the components into a magazine having a series of components locations for receiving such components, locating the magazine in alignment with the capstan of the lathe, and sucessively and sequentially carrying out the steps of rotating the capstan to bring component gripping means mounted on one station thereof into alignment with one of the components locations of the magazine, moving the gripping means into engagement with the component in said component location, withdrawing the gripping means with said component gripped thereby, rotating the capstan to bring the component gripping means into alignment with the chuck or collet of the lathe, advancing the gripping means to insert the component into the chuck or collet and withdrawing the gripping means, the magazine being indexed to bring another component location into alignment with the capstan between withdrawal of each component and advancing gripping means to engage with the subsequent component.

12. A method according to claim 11, wherein the component gripping means comprises a plurality of jaws resiliently biased into a gripping position with stop means opposing the resilient biasing so that the jaws are an interference fit with each component so as to grip it with a stronger frictional force than is exerted by the magazine but a smaller force than is exerted by the chuck or collet.

13. A component gripping assembly comprising a thrust member having a conical outer surface slidably mounted on a central support member, at least two levers spaced around the central support member and mounted for pivotal movement above axes forming a tangent to a circle centred on the axis of the thrust member and each having one end resting on the conical surface thereof, spring means for biasing the thrust member along the central member so as to force the said one ends of the levers apart and stop means for limiting outward movement of said one ends of the levers, the other ends of the levers forming jaws for gripping a component inserted therebetween.

14. An assembly according to claim 13, wherein the stop means comprises a respective adjustment screw for each lever.

15. An assembly according to claim 1 3 or 14, further comprising a buffer member adjustably mounted on said central support member for limiting the depth of insertion of a component between the jaws.

16. Apparatus for loading components into an automatic capstan lathe substantially as hereinbefore described with reference to the accompanying drawings.

17. Automatic lathe apparatus substantially as hereinbefore described with reference to the accompanying drawings.

18. A method of loading components into an automatic capstan lathe substantially as hereinbefore described with reference to the accompanying drawings.

19. A component gripping assembly substantially as hereinbefore described with reference to Figs. 2 and 3 of the accompanying drawings.