GB1595781A

GB1595781A - Cold heading machinery

Info

Publication number: GB1595781A
Application number: GB3734476A
Authority: GB
Original assignee: HUNSLET HOLDINGS Ltd
Current assignee: HUNSLET HOLDINGS Ltd
Priority date: 1977-12-09
Filing date: 1977-12-09
Publication date: 1981-08-19

Description

(54) IMPROVEMENTS TO COLD HEADING MACHINERY (71) We, HUNSLET (HOLDINGS) LIMITED of Hunslet Engine Works, Jack Lane, Leeds, West Yorkshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: It is known to manufacture headed components such as screw blanks for the fastener industry from metal stock in the form of wire or rods. One well known method utilises the double-blow type coldheading machine, in which wire or rod is converted into blanks by an automatic series of operations, as follows: (1) The wire or rod is fed into a cutting device which cuts a slug of wire to the required length.

(2) The slug is transferred, by means of fingers or any other gripping device into a space between the then open die and punch of a continuously running mechanical press.

(3) As the press closes, the slug is pushed into the die and the fingers or other gripping device withdraw. The slug encounters a stop, which locates the slug so that part of it projects from the die.

(4) A work blow is made on that part of the slug projecting from the die by a first punch tool carried on the moving press cross-head. This blow deforms the projecting part of the slug, as a first step towards the finished form of the head required ot be formed on the blank.

(5) The press withdraws, and by suitable mechanical means, the press cross-head is shifted so that a second punch tool is indexed in line with the die.

(6) The press closes again applying a second blow to the head, and this completes the formation of the head on the blank.

(7) The press withdraws and the press cross-head is shifted to bring the first punch again in line with the die.

The slug is ejected by a further mechanical means. A further cut slug is cut and transferred between the open tools of the press, this cutting and feeding operation being carried out during the operations described at (5) and (6) above.

All these steps are mechanically synchronised by means of cams and links driven from the press crankshaft. The speed of the process varies with the diameter of wire or rod forming the feed stock. Typically, speeds of 600 components per minute can be achieved with machines operating on wire of the order of 1.5 millimetres diameter, but this number falls to 150 components per minute with machines operating on wire of the order of 10 millimetres diameter.

Reference has been made above to the formation of heads on screw blanks, but it will be appreciated that the forging method described could be used to produce any reqiured head formation on a slug of wire or rod. For convenience, reference will be made to cold-heading, but it is to be understood that the invention is not restricted to the production of screw blanks.

It has been proposed to increase the productivity of the cold-heading process by using two dies, and at least two punches in the machine, with provision for indexing the punches between successive strokes of the press, so that a first punch operates on the slug in one die simultaneously with the second punch operating on the slug in the other die. In this way, it is possible to produce a finished blank at each stroke of the press.This method comprises a cycle including the steps of: - Feeding a second slug to a second die whilst the press is open, with a first slug on which a first operation has already been carried out held in a first die; closing the press to bring a first operation punch on to the second slug to perform a first forming operation on the second slug and simultaneously to bring a second operating punch on to the first slug to perform a second forming operation on the first slug; opening the press; ejecting the first slug from the first die; feeding a third slug to the first die; shifting the alignment of the punches relatively to the dies; closing the press to bring a second operation punch on to the second slug to perform the second operation on that slug, and simultaneously to bring a first operation punch on to the third slug to perform a first forming operation on the third slug; opening the press and ejecting the second slug from the second die.

It will be apparent that the cycle is continuous. Each time the press is opened a completed blank (i.e. one on which two forming operations have been performed by two punches) is ejected from one or other of the two dies and a fresh slug is presented to that die, and each time the die closes, the fresh slug which has just been presented to the die has the first operation carried out on it whilst the second operation is being carried out on the other slug. As a corollary to that, it will be clear that a fresh slug is presented to one die when the press is opened and to the other die on the succeeding opening of the press.

Although this proposed method is attractive, because of the potential improved productivity, in practice it has not been very successful. One of the principal reasons for this is that it is necessary to provide two sets of stock and two stock feed mechanisms, which have to feed their respective stock to the two dies. The feed mechanism is itself quite complicated and each feed mechanism must be separately synchronised with the press cross-head.

According to this invention a coldheading press has first and second dies for receiving slugs of wire or rod; a mechanism for shifting a punch holder to bring alternative punch locations on that holder into line with the dies; a stock cutter for cutting off slugs of wire or rod, the sock cutter comprising a shearing device which is adapted to move with a shearing action from a receiving position where it is able to receive axially fed stock, to first and second presentation positions, and first and second slug presenters each adapted to take a slug cut off by the stock cutter, from the cutter at a respective one of the presentation positions and further adapted to transfer the slug to a respective one of the two dies.The stock cutter preferably has two shearing bushes each of which is adapted to be brought to the receiving position where it receives the stock, and the movement of the stock cutter is arranged to be such that in a first shearing movement in one direction, one of the bushes carries a cut off slug into the first presentation position, and in a second shearing movement in a second direction, the other bush carries a second cut off slug into the second presentation position.

Preferably each presentation position is in a plane containing the axis of its respective die, whereby the stock presenters are each adapted to move in a single plane.

The operating mechanism for the stock cutter may be driven by stock cutter cam means driven from the press crankshaft which drives the punch holder, and in the preferred construction there is a cam shaft geared to the crankshaft so that the cam shaft rotates at one half the angular velocity of the crankshaft, the stock cutter cam means being adapted to produce movement of the stock cutter once in each direction during a single revolution of the cam shaft, whereby the stock cutter moves only in one direction between first and second strokes of the press and in the opposite direction between the second and third strokes of the press.

According to a preferred feature of the inventioin the arrangement is such that each of the planes containing one of the presentation positions and the axis of a respective die is flat and each of the stock presenters has a rectilinear motion in the said plane.

Preferably the stock presenters are each adapted to be operated by presenter cam means driven from the press crankshaft, and in the preferred arrangement, the presenter cam means is provided on the cam shaft and adapted to produce movement of each presenter during a single revolution of the cam shaft, whereby the presenters are reciprocated respectively on alternate strokes of the press. If presenter cam means are mounted on the cam shaft carrying the stock cutter cam means, then the presenters are automatically synchronised with the stock cutter.

According to yet another preferred feature of the invention a stock pusher is aligned with each of the presentation positions each stock pusher being adapted to move in the axial direction of the slug and to push the slug axially out of the cutter into the stock presenter at a time when the latter is in a retracted position.

The pushers are preferably operated by pusher cam means mounted on the cam shaft, the pushers being adapted to operate alternately in synchronism with the stock presenters.

Each stock presenter preferably has a pair of fingers resiliently loaded towards each other for the purpose of gripping a slug.

Preferably the punch holder has three punch locations and the shifting mechanism is adapted to align a first punch location with the first die and a second punch location with the second die on a first stroke of the machine; the second punch location with the first die and the third punch location with the second die on the next succeeding stroke; and to restore the alignment of the first and second punch locations with the first and second dies respectively on the next succeeding stroke.

In a preferred construction, the punch holder is adapted to provide locations for three punches in a linear arrangement parallel with a line joining the axes of the dies, the shifting mechanism being adapted to reciprocate the punch holder in the linear direction and the amplitude of the reciprocatory motion being equal to the spacing between the axes of the dies. The punch holder shifting mechanism is preferably operated by a cam mechanism driven from the press crankshaft, through a two: one angular velocity reduction, whereby the punch holder moves only in one direction between first and second strokes of the press and in the opposite direction between the second and third strokes of the press.

By using the invention, it is possible to produce a component at each opening and closing cycle of the press. Theoretically therefore, it is possible to double the production rate, and in practice a considerable increase in productivity can be achieved.

In general, the production of cold forged heads of the type generally encountered in the fastener trade and produced by two blow methods requires a blow energy on the first blow only of the order of 15% of that required for the second blow. It follows therefore, that the blow energy required in any one stroke when two operations are being carried out simultaneously will only be approximately 115% of that required for the second blow of a conventional double blow heading press.

Moreover, the disadvantages of a machine having two separate stock supplies are overcome, because there is only a single supply and each of the presenters has a simple rectilinear motion.

One construction of a cold-heading press in accordance with the invention, and its method of operation, will now be described by way of example only, with reference to the accompanying drawings, in which: - Figure 1 is a plan view of part of the press, showing the die and punch holder arrangement, Figure 2 is a plan view of a wire feed mechanism, Figure 3 is an end view of the wire feed mechanism looking in the direction of arrow III in Figure 2, Figure 4 is an elevation looking in the direction of arrow IV in Figure 3, Figure 5 is a diagrammatic perspective view showing the operation of a stock cutter, Figure 6 is an end view of the stock cutter, Figure 7 is a diagrammatic perspective view showing a presenter mechanism, Figure 8 is a diagrammatic perspective view of a punch holder shifting mechanism, Figure 9 is a section through a die head and part of the cross head of the machine in an open position, Figure 10 is a view similar to Figure 9, but showing the end of a first operating stroke, Figure 11 is a view similar to Figure 9, but showing the position after the cross head has been withdrawn following the first stroke, and Figure 12 is a view similar to Figure 9, but showing the end of a second operating stroke.

GENERAL LAYOUT OF MACHINE Referring to Figure 1, there is illustrated the general layout of certain important features of the machine. Part of the machine frame is shown at 20, and at one end, a die block 22 is secured to the frame. This block 22 receives first and second replaceable dies 24 and 26 (see also Figures 9 to 12) which are made in hardened steel, and which are bored at 28 and 30 to receive slugs cut off from the wire stock which is fed to the machine.

The diameter of the bore of each die determines the diameter of the wire which can be used in the machine, but by changing the dies, it is possible to vary the diameter of the wire which is being used.

It is necessary for both the dies 24 and 26 to have the same bore size, since only one stock of wire is used on the machine at any one time.

A press crankshaft 32 is driven by an electric motor (not shown) through a flywheel (not shown) mounted on one end of the crankshaft. The crankshaft 32 is mounted in journal bearings 34 and 36, for rotation about its own axis. The crank throw 38 is adapted to produce the necessary reciprocation of a cross-head 40, through a connecting rod 42, which is pivoted on the crank throw 38 and on a pin 44 in the cross-head. The cross-head 40 is mounted in horizontal slides 46 and 48, fixed to the frame 20, which ensure that the cross-head has a simple rectilinear reciprocatory motion as indicated by the arrow A. A punch holder 50 is mounted on the front of the cross-head 40 (the mounting providing for vertical reciprocation of the punch holder as will hereinafter appear).The cross-head is shown in the projected position, where the front face of the punch holder is near to the face of the die block 22, the retracted position of the front face of the punch holder being indicated by a chain-dotted line 50a in Figure 1.

A bevel gear pinion 52 is keyed sun to one end of the crankshaft 32, and meshes with a bevel gear wheel 54 keyed on to a cam shaft 56 which is journalled in bearings 58, 60 and 62 mounted in the frame 20. The wheel 54 is twice the diameter of the pinion 52, so that the cam shaft 56 rotates at half the angular velocity of the crankshaft 32 and hence the cam shaft rotates once for every two complete reciprocations of the cross-head 40. The cam shaft 56 provides the means for driving a stock cutter 64 and a stock presenter 66 (see Figure 1) and the cam shaft extends to the right of the bearing 62 to provide a means for driving a wire feed mechanism which is illustrated in Figures 2, 3 and 4.

WIRE FEED MECHANISM A bracket 68 (see Figures 2, 3 and 4) bolted on to the end of the frame 20 provides a further bearing for the cam shaft 56, and a pair of conjugate cams 70 and 72 is keyed on to the shaft 56 within the bracket 68, each of these cams being adapted to engage with a respective roller follower 74 or 76. The followers 74 and 76 are carried by a short driving lever 78 pivoted on an axle 80 carried by upstanding lugs 82 forming part of a bracket 84 bolted to the end of the frame 20. The driving lever 78 has a nose member 86 with an arcuate pushing face, which engages with a surface on a driven lever 88 pivoted on an axle 90 also carried by the lugs 82. The nose member 86 is mounted on a screw 92, so that its position along the length of the driving lever 78 can be adjusted. This provides a means of adjustment to the mechanical advantage between the two levers 78 and 88.

The driven lever 88 has an arm 94 to which one end of a presser rod 96 is connected. A bottom lever 98 is pivoted on an axle 100 carried by the frame 20, and the lower end of the presser rod is pivotally connected to the bottom lever part way along its length. At its free end, the bottom lever 98 is pivotally connected to the lower end of a link 102, the upper end of which is connected to a driving lever 104 pivoted on an axle 106 carried by an extension from the bracket 84.

It will be apparent, that at each half revolution of the cam shaft 56, one of the cams 70 and 72 will rock the driving lever 78, which will in turn rock the driven lever 88. This causes the presser rod 96 to depress the lever 98, pulling down the link 102 and turning the driving lever 104 about its axis. The conjugate cams ensure that the lever system tends to return to a rest position where the bottom lever 98 is raised.

A pawl 108 is mounted on the lever 104 and engages with ratchet teeth (not shown) on a clutch 110 keyed on to the axle 106.

Hence, at each oscillation of the lever 104, brought about by the action of one of the cams 70 and 72, the clutch 110 turns the shaft through a predetermined angle, which can be varied by adjustment of the nose member 86. A gear pinion 112 is also keyed on to the axle 106, this pinion driving a pair of equal diameter gear wheels 114 and 116 keyed respectively on to a pair of shafts 118 and 120. The shafts 118 and 120 are journalled in a block 122 carried by the frame 20, and grooved wire-feed wheels 124 and 126 are keyed respectively on to the shafts 118 and 120, the feedwheels co-operating with each other in known manner to forward wire stock between them (the wire being coiled once around one of the wheels to obtain a good purchase.

Now by virtue of the driving mechanism just described, the wire-feed wheels turn through a small angle, twice for each revolution of the cam shaft 56, that is once for each reciprocation of the cross-head 40, and each time they turn, they feed a short length of wire sufficient to form a slug of the required length for the cold-heading operation. In fact, the mechanical advantage of the lever system is adjusted so that the wire-feed wheels tend to slightly over feed the wire at each operation. It will be appreciated that the machine is equipped with the usual guide rollers for guiding the wire stock to the feed-wheels 124 and 126, and it is a significant fact that only one wire stock is used on the machine.

A gauge stop 121 is. carried by an arm 123 projecting from a block 125 on the frame 20, the end of the stop being aligned with the path of the wire-feed B-B (see Figure 1). The wire being fed by the wheels 124 and 126 engages with the stop 121 and is arrested by it. This determines the length of the slug to be cut off the wire as will hereinafter appear. It is possible to adjust the arm 123 on the block 125, to preselect the length of the slug which is to be formed in this manner.

CUT OFF MECHANISM Referring now to Figure 5, wire from the stock is fed axially by the previously described mechanism along an axis indicated by a chain-dotted line B-B (see also Figure 1). This axis is located midway between the axes of the dies 24 and 26, and it is an important feature of the invention, that the wire from the single supply of wire stock is fed from the supply along a single axis. The stock cutter 64 is located in a recess 130 of the die block 22 the inner face of the cutter being in the same plane as the inner faces of the dies 24 and 26.

As is apparent from Figure 6, the cutter 64 basically comprises a bell-cranked level adapted for rocking motion about an axis 132. At its operative end, the stock cutter 64 carries a pair of hardened cutting bushes 134 and 136 displaced vertically from each other, and in one of two possible positions of rest of the stock cutter 64, which is illustrated in Figure 5, the upper bush 134 is in axial alignment with the wire-feed (B-B), whilst the lower bush 136 is at a second presentation position in a horizontal plane containing the axis of the lower die 26. Hence, the vertical displacement between the axes of the upper and lower bushes is one half fhe vertical displacement between the axes of the dies 24 and 26.

When the stock cutter 64 turns about the pivot 132 from the position shown in Figure 5 to its alternative position, the upper bush 134 is in a first position where its axis is in the horizontal plane containing the axis of the upper die 24, and the lower bush 136 is brought into alignment with the wire-feed (B-B). The wire-feed mechanism projects the measured length of wire through whichever of the bushes 134 and 136 is aligned with the wire feed axis, the total length of wire in the bush 134 or 136, and projecting on the right hand side thereof, as seen in Figure 5 up to the stop 21, equalling the total length of a slug for use in the machine. When the cutter 64 moves from one position to another, during a first part of the movement, it shears off this measured length of wire, thus producing a separated slug for presentation to the upper or lower die as the case may be.The remaining part of the movement of the cutter is necessary to bring the slug into alignment with one or other of the dies.

A lay shaft 140 is journalled in a part of the frame 20 parallel with the cam shaft 56, and a first set of three levers 142, 144 and 146 is splined on this lay shaft, there being a roller follower 148 carried by the levers 142 and 144 and a second roller follower 150 carried by the levers 144 and 146. A pair of cut off cams 152 and 154 is keyed on to the cam shaft 56, the cam 152 being aligned with the follower 148 and the cam 154 being aligned with the follower 150. The two cams are set at 1800 to each other and so arranged that at each revolution of the cam shaft, the cam 152 turns the set of three levers (and hence the lay shaft 140) in one direction, and, after a dwell, the cam 154 turns the set of three levers (and hence the lay shaft 140) in the opposite direction.

A link 156 is connected between the levers 142 and 144 at one end and the bell cranked lever 64 which forms the stock cutter at the other end. As a result of the action of the cams 152 and 154, the stock cutter is turned about its pivot 132 to carry the bushes 134 and 136 in an upward direction on one operation of the crosshead 40, and in the downward direction on the next operation of the crankshaft.The cams 152 and 154 are only designed to produce the actual shearing action of the cutter 64, but a further pair of cams 158 and 160 mounted on the cam shaft 56 is connected to the cutter 64 via followers 162 and 164, a set of three levers 166, 168 and 170 similar to the levers 142, 144 and 146, and the lay shaft 140, the cams 158 and 160 being designed to provide the additional movement of the cutter 64 to bring the slug in one of its bushes 134 and 136 into the horizontal plane containing the axis of one of the dies 24 and 26. Stops (not shown) are provided to limit the movement of the cutter 64 in each of its positions of rest, where one of its bushes is in the horizontal plane of one of the dies, and its other bush is in alignment with the wire feed path B-B.

SLUG TRANSFER MECHANISM First and second slug pushers 135 and 137 are provided, and each of these is connected to a cam operated mechanism, operated from the machine crankshaft, so that it has a rectilinear reciprocatory motion parallel with the motion of the cross-head. The pushers have their axes respectively in the same horizontal planes as the axes of the dies 24 and 26. The arrangement of the pushers is such that the pusher 135 is in axial alignment with the bush 134 of the stock cutter when that bush has completed a cutting action and is at rest in the first presentation position, and the pusher 137, is in axial alignment with the bush 136 when that bush has completed a cutting action and is at rest in the second presentation position.

The driving mechanism for the pushers is arranged so that the pushers reciprocate alternately, on the opening of the press, the synchronisation being arranged so that the pusher which is aligned with the bush 134 or 136 which has just carried out a shearing operation, is projected. The extent of the reciprocation of the pusher is such that it pushes the sheared off slug carried by the bush 134 or 136 completely out of the bush (to the left as seen in Figure 1), to a position where it can be transferred by a simple horizontal movement, into axial alignment with its respective die 24 or 26, ready to be pushed into that die by a punch.

A slug presenter arrangement is illustrated in Figure 7 of the drawings, and essentially comprises first and second slug presenters 172 and 174. Since these presenters are substantially identical in construction, it is only necessary to describe one in detail. The upper (first) presenter 172 has a cylindrical finger arm 176, which is slidable in a bore 178 in the frame 20 (see Figure 1) in a direction indicated by the arrow P in Figure 7, this direction being at right angles to the direction of movement of the cross-head 40. At its operative end, the finger arm 176 carries a bracket 180, which is capable of some vertical adjustment relatively to the finger arm 176, there being a pair of fingers 182 and 184 pivotally mounted on the bracket 180.

A finger operating mechanism (not shown) within the presenter arm 176 is cam actuated, and includes a gear tooth rack meshing with gear tooth quadrants on the axles of the fingers 182 and 184. This mechanism is arranged to open and close the fingers, against the action of a spring loading within the arm 176, in synchronism with the operation of the cross-head 40.

The location of the fingers is such that their operative ends are capable of holding a wire slug in the same horizontal plane as the axis of the top die 24.

A recess 186 is formed ino the outer end of the arm 176 and a bulbous head 188 formed on a bell cranked lever 190 engages in this recess for pushing the finger arm inwardly and outwardly (i.e. sliding in the bore 178 in the direction of the arrow P).

The lever 190 is pivoted at 192, and its lower arm 194 is bifurcated, with a follower roller 196 mounted in the clevis formed by the lower arm. A compression spring 198 acts against the underside of a spring cap 200 mounted on an adapter carried by the arm 194, thus urging that arm upwardly and hence urging the finger arm 176 inwardly.

The follower 196 engages with a cam 202 mounted on the cam shaft 56. The cam 202 is designed to turn the lever 190 against its spring loading to draw the finger arm 176 outwardly to a position of rest where the operative ends of the fingers (which at that time are open) are in axial alignment with the bush of the cutter 64 which has just come to rest after a cut off operation. The cam design is such however, that when it rotates, it allows the finger arm 176 to move inwardly until the operative ends of the fingers (which close during this inward movement) are in axial align ment with the die 24 with which the pre senter 172 is associated.

Now when the first presenter 172 is re tracted, the cutter 64 will have just com pleted a cuting operation in an upward direction, the cut slug being held in the upper bush 134 at a first presentation posi tion. The pusher is then operated to push this slug into the then open fingers 182 and 184. The slug remains in the same horizontal plane as the die 24, but is now clear of the cutter 64. The fingers 182 and 184 close on to the slug to grip it, and then the presenter moves inwardly until it has located the slug in axial alignment with the die 24. At that stage, the fingers release their grip on the slug as it is being pushed into the die as will be hereinafter described, by a punch. The presenter 172 then retracts.

The second presenter 174 operates in exactly the same manner as the presenter 172, excepting that its cam is set 180C out of phase with the cam 202, so that it presents its slug to the lower die 26 on the next operation of the cros-head 40 after that at which the presenter 172 is actuated.

In Figure 7, a cut slug carried by the lower bush 136 of the stock cutter 64 is in engagement with the fingers 182 and 184 of the lower presenter 174. The presenter 174 is therefore in a retracted position, although as shown in Figure 7, the lower slug pusher has not yet operated to push the slug out of the bush 136. It will be understood, that the pusher only carries out this operation, when the fingers 182 and 184 of the lower presenter are already in engagement with the slug, so that the slug is kept constantly under control. As is shown in Figure 7, a fresh length of wire 204 is already being fed at the wire-feed station through the upper bush 134, but this will not be sheared off, until the stock cutter 64 moves at the next opening movement of the press.

The upper slug presenter 172 is shown in Figure 7 in a projected position, at which it presents a slug to the upper die 24. It will be appreciated therefore, that each slug presenter 172, 174 has a rectilinear operative motion, from the retracted position which is illustrated by the lower presenter 174, to the projected position, which is illustrated by the upper presenter 172.

PUNCH MECHANISM It has already been mentioned, that the punch holder 50 is vertically slidable in the front of the cross-head 40. As shown diagrammatically in Figure 8, a gear pinion 210 is keyed on to the crankshaft 32, and meshes with a gear wheel 212 keyed on to a punch lay shaft 214 lying parallel with the crankshaft 32. The lay shaft 214 is journalled in suitable bearings (not shown).

The gear wheel 212 is twice the diameter of the gear pinion 210, so that there is an angular velocity reduction of two: one between the crankshaft 32 and the lay shaft 214. Hence, the lay shaft turns at half the speed of the crankshaft 32.

The lay shaft 214 carries a pair of conjugate cams 216 and 218 adapted to en- gage respectively with cam followers 220 and 222, provided on a bracket 224, which is keyed on to a lifter shaft 226, which is also mounted in journal bearings, so that it is free to turn about its own longitudinal axis. The lifting shaft 226 carries a lever 228, the outer extremity of which is pivotally connected to a block 230 slidable horizontally, within a U-shaped slot in the lower end of the punch holder 50. The action of the conjugate cams 216 and 218 produces oscillation of the lifter shaft 226 about its own axis, and this in turn causes the lever 228 to raise and lower the punch holder 50.Any horizontal component of movement required between the punch holder 50 and the lever 228 is accommodated by sliding of the block 230 in the horizontal slot in the lower end of the punch holder 50. The shape of the cams 216 and 218 is such, that the punch holder 50 carries out its shifting movement in one direction or the other, each time the cross-head 40 is retracted to the fully open position illustrated at 50s in Figure 1 of the drawings.

Referring to Figures 9 to 12, there is shown the method of producing headed screw blanks on the machine. The die block 22 provides locations for the stationary dies 24 and 26, each of which is bored, to receive the slugs cut off from the wire or bar stock. An ejector pin 240, 242 is provided for each of the dies 24 and 26, the ejector pins being operated by a known mechanism (not shown) the motion being derived from the machine crankshaft 32.

In a projected position, illustrated in the upper part of Figure 9, the ejector 240 extends through the length of the first die 24, and hence completely ejects any slug from that die. On the other hand, in the retracted position which is shown in the lower part of Figure 9, the ejector 242 engages with a stop (not shown) and its pin provides a fixed location within the second die 26, so that when a slug of stock is inserted into the open end of the die, it is arrested, with sufficient material projecting from the face of the die, to form the head which is required on the blank.

It will be appreciated, that the ejector pins 240 and 242 reciprocate between the positions illustrated in the upper and lower parts of Figure 9, according to a required sequence of operations, which will hereinafter appear.

The punch holder 50 provides locations for three hardened punches 246, 248 and 250, located in a common vertical plane, which is aligned with the vertical plane joining the axes of the dies 24 and 26 in the die block 22. The punches 248 and 250, which are positioned in the upper and lower locations of the punch holder 50 are each adapted to perform a second head forming operation, whilst the punch 246, which is located at the central position in the pnnch holder 50, is adapted to perform a first head forming operation. The vertical displacement between the first punch 246, and each of the second punches 248 and 250, is equal to the vertical displacement between the axes of the dies 24 and 26.

At an initial open position, which is illustrated in Figure 9, a first slug 252, is already in position in the lower (secon) die 26, where it locates against the end of the ejector pin 242, and the first operation has already been carried out on the projecting poriton of the first slug 252, producing the partially formed head on the slug. During the opening movement of the press, a previously completed blank 254 is ejected from the upper (first) die 24 by means of the ejector pin 240, and at the same time, a fresh slug 258 is aligned with the die 24 by the presenter 172.

As the cros-head moves towards the die block 22 on the next stroke, the first punch 246 engages with the right hand end of the fresh slug 258 (as seen in Figures 9 to 12) and pushes that slug into the first die 24, until it is arrested by the ejector pin 240, which will then be in the retracted position. (The fingers of the presenter 172 relax their grip to allow the slug to be pushed by the punch 246.) Thereafter, the cross-head 40 carries out a working stroke the termination of which is illustrated in Figure 10. The first punch 246 carries out the first head forming operation on the freshly presented slug 258, and at the same time, the lower second punch 250 carries out the second and final head forming operation on the slug 252 in the lower die.

It is of course necessary to design the machine so as to be capable of carrying out both these head forming operations simultaneously, and in particular, this means that the machine must be able to stand up to the increased stresses, due to the fact that a total operating load equal to about 115% of the load normally required for a second head forming operation, is required at each stroke of the press.

When the cross-head retracts on the succeeding stroke, as is illustrated in Figure 11, the now completely formed blank 252 is ejected from the lower die 26 by the ejector pin 242, and a fresh slug 260 is presented to the lower die 26 by the presenter 174. At the same time, the punch holder 50 is shifted in a downward direction through a distance equal to the spacing between the axes of the upper and - lower dies, and this brings the first punch 246 into line with the lower die, and the upper second punch 248 into line with the upper die.On the succeeding operation stroke of the cross-head, which is shown in Figure 12, the first punch 246 carries out á first head forming operation on the freshly presented slug 260 in the lower die 26, and the upper second punch 248 carries out the second head forming operation on the upper slug 258 in the die 24. This completes the cycle of the machine because as the cross-head is withdrawn, the punch holder 50 is restored to its original position and the conditions are as illustrated in Figure 9.

It will be seen therefore, that when the first punch 246 is aligned with the upper die 24, the lower second punch 250 is aligned with the lower die, so that these two punches are able to carry out working strokes, but the upper second punch 248 is out of alignment with either of the dies, and therefore on the first working stroke as illustrated in Figure 10, the upper second punch 248 is inactive. Conversely, when the punch holder 50 is in the other position, the upper second punch 248 is aligned with the upper die 24, and the first punch 246 is aligned with the lower die 26, the lower second punch 250 being in an inactive position.

It sometimes happens that one of the second operation punches is out of action, because it is worn or broken. If so, then the worn punch can be removed, and one of the wire-feed cams 70 and 72 is disconnected. The wire-feed mechanism then only operates on alternate strokes of the die which has the operative second operation punch. The press produces all finished products, but of course, only at half the normal production rate. This is better than having to allow the press to stand idle, and it enables some production to continue despite the fact that one of the two second operation punches is out of service.

WHAT WE CLAIM IS: 1. A cold-heading press having first and second dies for receiving slugs of wire or rod; a mechanism for shifting a punch holder to bring alternative punch locations on that holder into line with the dies; a stock cutter for cuting off slugs of wire or rod, the stock cutter comprising a shearing device which is adapted to move with a shearing action from a receiving position where it is able to receive axially fed stock, to first and second presentation positions, and first and second slug presenters each adapted to take a slug cut off by the stock cutter, from the cutter at a respective one of the presentation positions, and further adapted to transfer the slug to a respective one of the two dies.

2. A cold-heading press as claimed in Claim 1, in which the stock cutter has two shearing bushes each of which is adapted to be brought to the receiving position where it receives the stock, and the movement of the stock cutter is arranged to be such that in a first shearing movement in one direction, one of the bushes carries a press so that slugs only arrive at the cut off slug into the first presentation position, and in a second shearing movement in a second direction, the other bush carries a second cut off slug into the second presentation position.

3. A cold-heading press as claimed in Claim 1 or Claim 2, in which each presentation position is in a plane containing the axis of its respective die, whereby the stock presenters are each adapted to move in that single plane.

4. A cold-heading press as claimed in any one of Claims 1 to 3, in which there is a press crankshaft for operating the punch holder the operating mechanism for the stock cutter being driven by stock cutter cam means driven from the press crankshaft.

5. A cold-heading machine as claimed in Claims 2 and 4, in which there is a camshaft geared to the crankshaft so that the cam shaft rotates at one half the angular velocity of the camshaft, the stock cutter cam means being adapted to produce movement of the stock cutter once in each direction during a single revolution of the cam shaft, whereby the stock cutter moves only in one direction, between first and second strokes of the press and in the opposite direction between the second and third strokes of the press.

6. A cold-heading machine as claimed in Claim 3 and either of Claims 4 and 5 so far as they depend from Claims 3, in which the arrangement is such that each of the planes containing one of the presentation positions and the axis of a respective die is flat and each of the stock presenters has a rectilinear motion in the said plane.

7. A cold-heading machine as claimed in any one of Claims 1 to 6, in which the stock presenters are each adapted to be operated by presenter cam means driven from the press crankshaft.

8. A cold-heading machine as claimed in Claims 5 and 7, in which the presenter cam means is provided on the camshaft and adapted to produce movement of each presenter during a single revolution of the camshaft, whereby the presenters are reciprocated respectively on alternate strokes of the press.

9. A cold-heading machine as claimed in any one of Claims 1 to 8, in which a stock pusher is aligned with each of the presentation positions, each stock pusher being adapted to move in the axial direction of the slug and to push the slug axially out of the cutter into the stock presenter at a time when the latter is in a retracted position.

10. A cold-heading machine as claimed in Claim 9, in which the pushers are operated by pusher cam means mounted on the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the second head forming operation on the upper slug 258 in the die 24. This completes the cycle of the machine because as the cross-head is withdrawn, the punch holder 50 is restored to its original position and the conditions are as illustrated in Figure 9. It will be seen therefore, that when the first punch 246 is aligned with the upper die 24, the lower second punch 250 is aligned with the lower die, so that these two punches are able to carry out working strokes, but the upper second punch 248 is out of alignment with either of the dies, and therefore on the first working stroke as illustrated in Figure 10, the upper second punch 248 is inactive. Conversely, when the punch holder 50 is in the other position, the upper second punch 248 is aligned with the upper die 24, and the first punch 246 is aligned with the lower die 26, the lower second punch 250 being in an inactive position. It sometimes happens that one of the second operation punches is out of action, because it is worn or broken. If so, then the worn punch can be removed, and one of the wire-feed cams 70 and 72 is disconnected. The wire-feed mechanism then only operates on alternate strokes of the die which has the operative second operation punch. The press produces all finished products, but of course, only at half the normal production rate. This is better than having to allow the press to stand idle, and it enables some production to continue despite the fact that one of the two second operation punches is out of service. WHAT WE CLAIM IS:

1. A cold-heading press having first and second dies for receiving slugs of wire or rod; a mechanism for shifting a punch holder to bring alternative punch locations on that holder into line with the dies; a stock cutter for cuting off slugs of wire or rod, the stock cutter comprising a shearing device which is adapted to move with a shearing action from a receiving position where it is able to receive axially fed stock, to first and second presentation positions, and first and second slug presenters each adapted to take a slug cut off by the stock cutter, from the cutter at a respective one of the presentation positions, and further adapted to transfer the slug to a respective one of the two dies.

camshaft, the pushers being adapted to operate alternately in synchronism with the stock presents.

11. A cold-heading machine as claimed in any one of Claims 1 to 10, in which each presenter has a pair of fingers resiliently loaded towards each other for the purpose of gripping a slug.

12. A cold-heading machine as claimed in any one of Claims 1 to 11, in which the punch holder has three punch locations and the shifting mechanism is adapted to align a first punch location with the first die and a second punch location with the second die on a first stroke of the machine; the second punch location with the first die and the third punch location with the second die on the next succeeding stroke; and to restore the alignment of the first and second punch locations with the first and second dies respectively on the next succeeding stroke.

13. A cold-heading machine as claimed in Claim 12, in which the punch holder is adapted to provide locations for three punches in a linear arrangement parallel with a line joining the axes of the dies, the shifting mechanism being adapted to reciprocate the punch holder in the linear direction and the amplitude of the reciprocatory motion being equal to the spacing between the axes of the dies.

14. A cold-heading machine as claimed in Claim 13, in which the punch holder shifting mechanism is operated by a cam mechanism driven from the press crankshaft, through a two: one angular velocity reduction, whereby the punch holder moves only in one direction between the first and second strokes of the press and in the opposite direction between the second and third strokes of the press.

15. A cold-heading machine constructed arranged and adapted to operate substantially as herein described with reference to the accompanying drawings.