GB2347889A

GB2347889A - Press tool feed mechanism

Info

Publication number: GB2347889A
Application number: GB9903238A
Authority: GB
Inventors: Michael David Bowen
Original assignee: UTILUX
Current assignee: UTILUX
Priority date: 1999-02-13
Filing date: 1999-02-13
Publication date: 2000-09-20
Also published as: GB9903238D0

Abstract

A feed mechanism for a press tool defining a feed path 15 for a work-piece 16 has a feed lever 20 mounted on the press tool frame 11 and pivotally supporting a feed finger 24 engageable with the work-piece 16 to effect successive feeding movements of the work-piece as the feed lever pivots. A cam mechanism has a cam surface 31 mounted on the press tool ram 12 and a cam follower 27 on the feed lever 20 so that the lever performs one feed cycle for each pressing cycle of the ram. The cam surface 31 is defined by a cam block 28 adjustably mounted on the ram whereby the feed length of the workpiece may be adjusted, for each cycle of operation.

Description

PRESS TOOL FEED MECHANISM This invention relates to a feed mechanism for a press tool having a frame which slidably supports a ram, for operating on a work-piece. The invention further relates to a press tool having a feed mechanism for a workpiece.

Press tools are widely used in the engineering industry, for a wide variety of operations on a work-piece, including press-forming, punching, diestamping, slotting and so on. A press tool typically has a main frame adapted for mounting on one bolster of a press, and a ram slidably mounted with respect to the frame, for operation by the other bolster of the press. The two parts of the required tooling for the operation to be performed are mounted respectively on the frame and the ram.

In a production engineering environment, some kind of automated feed device for a work-piece is required, which operates in a timed relationship to the movement of the ram. It is known to provide a feed mechanism having a complex arrangement of inter-connected levers which, upon operation, causes a work-piece to be advanced to a pre-set index position, the mechanism being operated by a cam arrangement provided on the ram. Adjustment of such a mechanism to permit adjustment of the feed length of the work-piece is complex and usually requires physically changing some of the components.

Then, fine adjustment may be performed by mounting at least some of the levers on eccentric pivots, so that rotation of those pivots changes the geometry of the mechanism. The adjustment of such a mechanism to give a particular feed length is thus difficult and time consuming, and usually requires several attempts before the required feed length is consistently achieved.

The present invention aims at overcoming the disadvantages of the known form of adjustable feed mechanism as described above, for a press tool. Accordingly, this invention provides a feed mechanism for a press having a frame defining a feed path for a work-piece to be pressed and slidably supporting a press tool for movement generally perpendicular to the length of the feed path, wherein there is provided a feed lever pivotally mounted on the frame, a feed finger pivoted to the feed lever and engageable with the work-piece to effect successive feeding movements thereof upon the feed lever rocking about its pivotal mounting, a cam mechanism comprising a cam surface on the press tool and a cam follower on the lever which mechanism operates to cause the lever to perform a one feed cycle for each pressing cycle of the press tool, the cam surface being defined by a cam block adjustably mounted on the press tool to permit adjustment of the length of work-piece fed on each cycle of operation.

The feed mechanism of this invention is relatively simple and moreover may readily be adjusted to give different feed lengths, simply by adjusting the position of the cam block on the ram. Preferably, means are provided to constrain the adjusting movement of the cam block to be substantially linear, and advantageously in a direction essentially parallel to the length of the feed path defined by the frame. For example, a linear slot may be provided through the cam block, with a bolt extending through that slot and into the ram, so that the bolt may clamp the cam block to a suitable surface of the ram.

The cam block may have a cam surface profile designed to ensure that the feeding of a work-piece takes place while the tooling is open, either on the down stroke of the ram or on the up stroke, the feed mechanism then dwelling whilst the operation on the work-piece takes place. However, it is preferred for the cam block to be formed in two parts, with one part providing a camming surface which effects feeding movement of the work-piece and the other part providing a cam surface which gives the required dwell. Then, by arranging the two parts of the cam block to be relatively adjustable, both with respect to each other and the ram, it is relatively easy to set up the feed mechanism to give firstly the required work-piece feed length and secondly the required dwell to permit performance of the operation on the work-piece.

In the preferred form of the invention, where the cam block is in two parts, one part preferably has a linear camming surface which lies at an angle to the line of operation of the ram, and the other part has a linear cam surface which extends substantially parallel to the line of movement of the ram. Then, appropriate adjustment of the two parts will allow selection of the feed distance and dwell time.

Adjustment of the cam block may be facilitated by means of a screwthreaded adjuster, threaded into the ram and engaged with the cam block.

Such an adjuster may have an enlarged head which bears against a reference surface of the cam block, to ensure the cam block lies at the required angle with respect to the line of movement of the ram. In a case where the cam block is in two parts, as described above, two such screw-threaded adjusters may be provided, one for each part respectively of the cam block.

This invention extends to a press tool having a frame defining a feed path for a work-piece to be pressed and slidably supporting a ram for movement generally perpendicular to the length of the feed path, in combination with a feed mechanism of this invention as described above.

By way of example only, one embodiment of a press tool provided with a work-piece feed mechanism arranged in accordance with the present invention will now be described in detail, reference being made to the accompanying drawings, in which : Figure 1 is a side view of the press tool including the feed mechanism; Figure 2 is a detaiied view on an enlarged scale of the feed mechanism ; and Figure 3 is an end view on the cam block arrangement of the feed mechanism shown in Figure 2.

Referring initially to Figure 1, there is shown a press tool having a base 10 from which upstands a guide pillar 11, a ram 12 being mounted on the pillar 11 for sliding movement towards and away from the base 10. Tooling configured to perform the required press operation on a work-piece has two co-operating parts 13 and 14, mounted respectively on the base 10 and ram 12. The base 10 defines a feed path 15 for a work-piece 16, along which the work-piece is intermittently fed by the required distance, for the press operation to be performed thereon.

Thus far, the press tool is entirely conventional and is used by mounting the base 10 on one bolster of a press, the ram 12 being coupled to the other bolster of a press, for example by means of the inter-connection spigot 17. Cycling the press will thus cause the tooling 13,14 to perform the required operation on that part of the work-piece for the time being located in the throat of the press, between the two tooling parts.

The press is fitted with a work-piece feed mechanism having a feed lever 20 pivoted by pin 21 to bracket 22 projecting from the guide pillar 11, pin 21 extending parallel to the base 10 and transverse to the length of the feed path 15. Pivoted to the lower end 23 of the lever 20 is a feed finger 24 having a tip 25 appropriately profile for inter-engagement with abutments 26 formed on the work-piece 16 lying on the feed path 15. In the present case, the workpiece comprises a length of individual part-formed wire terminals drawn from a roll (not shown). Each terminal is crimped to the bare end of a respective wire and is cropped from the uncrimped terminals by the press operation. The tip 25 of the feed finger is, in the illustrated embodiment, configured to engage an upstanding part 26 of each terminal, but for other work-pieces may take a different configuration, to inter-engage with a suitable part of those workpieces.

A cam mechanism is formed between the ram 12 and the other end of the lever 20, this mechanism comprising a rotatable cam follower 27 mounted on the upper end of lever 20 and a cam block 28 clamped to the ram 12 by means of a bolt 29. This cam block comprises a first part 30 defining an incline feed cam surface 31 and a second part 32 defining a dwell cam surface 33. The feed cam surface 31 extends at an acute angle to the line of action of ram 12, whereas the dwell cam surface 33 extends substantially parallel to the line of action of the ram. The first part 30 is forked so as to define a channel between the two sides of the cam block part, and the second part 32 is in the form of a plate received in that channel, as best seen in Figure 3. Further, the first part 30 defines an additional cam surface 34, below the incline surface 31, which additional cam surface 34 extends substantially parallel to cam surface 33.

Both sides of the first part 30 are formed with an elongate slot 35, a corresponding slot also being formed in the second part 32, so that the bolt 29 may extend through those slots to be threaded into the ram 12. In this way, loosening of the bolt 29 allows both the first and second cam parts 30,32 to be adjusted independently, forwards and backwards along the feed path 15, subsequent tightening of the bolt 29 then securing both cam parts in their chosen positions. Adjustment of each cam part 30,32 is facilitated by a pair of respective screw-threaded adjusters 36,37, threaded into the ram 12.

Each adjuster has an enlarged knurled head 38,39, which engages a back face on the respective cam part, each adjuster being fitted with a respective helical compression spring 40,41 which resists rotation of the associated adjuster.

A spring (not shown) is arranged to urge the lever 20 in a counterclockwise sense, so that the cam follower 27 bears on one of the cam surfaces, dependent upon the vertical position of the ram 12. When the ram is fully raised, the follower 27 will bear on the additional cam surface 34.

Then, as the ram is pushed down, the lever will turn counter-clockwise so drawing the feed finger from the left hand abutment (in Figure 3) to the right, so as to ride over the next adjacent abutment 26. During the last stage of the ram descent, when a press operation on a work-piece takes place, the follower 27 runs over the dwell cam surface 33 with the lever remaining static.

On the return of the ram 12, as the follower runs over the incline feed cam surface 31, the lever 20 is driven in a clockwise sense, so driving the feed finger 24 to the left, and thus advancing the work-piece through one feed length. The cam follower 27 is arranged to run along the additional cam surface 34, when the required work-piece length has been advanced.

The mechanism is adjusted by loosening the locking bolt 29 and then turning the adjusters 36 and 37 as appropriate, whereafter the bolt 29 is retightened. Initially, the second part 32 is adjusted when the follower 27 bears on its dwell cam surface 33 to set the rearward position of the feed finger; then, the ram is raised so that the follower is on the additional cam surface 34 and the first part 30 is adjusted, to give the required stroke to the feed finger 24. Though it is envisaged that a wide range of adjustment can be achieved by appropriate movement of the first and second parts 30,32 of the cam block, it is a relatively simple matter to replace those parts by others having different profiles, so as to alter the overall mechanical characteristics.

Moreover, the second part 32 may be modified so that its cam surface also is incline to the line of action of the ram, so as to obtain a feeding effect on the down stroke of the ram; this would be achieved by inclining its cam surface in the opposite sense to cam surface 31. In such a case, the cam surface 31 may be incline or could be parallel to the line of action of the ram.

It will be appreciated that the mechanism of this invention is relatively simple and is easy to adjust, especially since the operator can observe the effect of the adjustment of the cams, by having the cam follower resting on the appropriate cam surface during adjustment. In turn, this saves considerable time in setting up the mechanism, as compared to those currently available.

Claims

CLAIMS 1. A feed mechanism for a press tool having a frame defining a feed path for a work-piece to be pressed and slidably supporting a ram for movement generally perpendicular to the length of the feed path, wherein there is provided a feed lever pivotally mounted on the frame, a feed finger pivoted to the feed lever and engageable with the work-piece to effect successive feeding movements thereof upon the feed lever rocking about its pivotal mounting, a cam mechanism comprising a cam surface on the ram and a cam follower on the lever which mechanism operates to cause the lever to perform a one feed cycle for each pressing cycle of the ram, the cam surface being defined by a cam block adjustably mounted on the ram to permit adjustment of the length of work-piece fed on each cycle of operation.
2. A feed mechanism as claimed in claim 1, wherein the cam block provides two cam surfaces one of which is incline to the line of movement of the ram and the other of which is substantially parallel to said line of movement.
3. A feed mechanism as claimed in claim 2, wherein the cam block is in two parts respectively providing the inclined and parallel cam surfaces.
4. A feed mechanism as claimed in claim 3, wherein the two parts of the cam block are independently adjustable with respect to the ram and to each other.
5. A feed mechanism as claimed in claim 4, wherein each part of the cam block has a respective a slot which slots are aligned and the two parts are clamped to the ram by means of a common screw-threaded fastener extending through the aligned slots.
6. A feed mechanism as claimed in any of the preceding claims, wherein the cam block or each part thereof is mounted for substantially linear adjusting movement.
7. A feed mechanism as claimed in claim 6, wherein the cam block or each part thereof is mounted for adjusting movement in a direction substantially parallel to the length of the feed path defined by the frame.
8. A feed mechanism as claimed in any of the preceding claims, wherein a screw-threaded adjuster is provided for the cam block.
9. A feed mechanism as claimed in any of claims 3 to 5, wherein a screwthreaded adjuster is provided for each part of the cam block.
10. A feed mechanism as claimed in claim 1 and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
11. A press tool having a frame defining a feed path for a work-piece to be pressed and slidably supporting a ram for movement generally perpendicular to the length of the feed path, in combination with a feed mechanism as claimed in any of the preceding claims.