AU675590B2 - Clinching die - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "CLINCHING DIE" The following statement is a full description of this invention, including the best method of performing it known to the Applicant:- Technical Field This invention relates to the formation of press-formed clinches in sot* sheet materials, whereby two overlapping sheets of the material may be joined together without the need for additional items or material.

Background Art Conventionally, such clinches are formed by a co-acting male punch and female die. The punch and die face each other, with the overlapped sheets between them, and the clinch is formed by the punch moving towards the die so as to displace a small portion of the sheet I-imaterial into the die cavity. The mouth of the die cavity is partly defined by spaced apart cutting edges corresponding to complementary cutting edges on the punch that partly define the periphery of its leading face.

Those complementary cutting edges are adapted to act as shear blades, whereas the remainder of the cavity mouth is either undefined or is well spaced from the remainder of the periphery of the punch. Thus, as the punch moves towards the die cavity, it displaces coinciding portions of the overlapped sheets ahead of it into the die cavity while shearing the sheets along parts of the periphery of the displaced portions. Thus, the displaced portions are partly severed from the remainder of the sheets, and the material in the unsheared parts of the periphery of the displaced portions is stretched and remains as connections between the displaced portions and the rest of the sheets.

When the displaced portions are clear, or at least partly clear, of the rest of the sheets, they are squeezed, and so caused to spread laterally until their sheared edge margins overlap adjacent parts of the sheets, This squeezing and spreading is sometimes referred to as "lateral extrusion".

In some instances the displacement and the lateral extrusion are effected sequentially in separate stations, in others (for example, as disclosed in the specifications of lapsed Australian patent application 11,149/76 (Malleys) and U.S. patents 2,254,558 (Williams) and 4,614,017 (Eckold) incorporated herein by reference), the leading face of the punch coacts with the floor of the die cavity as an anvil to effect the lateral extrusion That is to say, in these latter instances, the one punch and die set effects the severing, displacing and lateral extrusion, at one station, irn a single operation.

c-I I L Ld As shown in the above mentioned specifications and in other prior art, the die cavity must either be larger near its floor than it is at its mouth, or must be capable of expanding, to accommodate and allow the lateral extrusion to occur. This is most usually achieved by using a multi-part die wherein those parts which carry the die cutting edges are blades that are resilient, or resiliently mounted, to enable them to separate as the lateral extrusion occurs.

The present invention is concerned solely with the last mentioned, expandable, multi-part dies, that enable severing, displacing and lateral lo extrusion to be performed in a single operation. Such dies are referred to as "dual function clinching dies" hereinafter, A disability of known dual function clinching dies is their propensity to produce chips, that is to say, small shreds of severed material, which

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fe sometimes become lodged between the die parts and prevent the full Sg.

return of a resiliently movable part to its non-expanded or cutting position after the lateral extrusion of a prior operation has been concluded, 0%.

An object of the present invention Is to overcome the aforesaid m disability.

Disclosure of Invention The invention consists In a dual function clinching die comprising an anvil portion and at least two cutting blades flanking the anvil portion, and which are movable from a cutting position adjacent to the anvil portion, to a lateral extrusion position spaced from the anvil portion; which die further comprises chip clearing means comprising duct means S2 I r I C -I L- Ifor the release of compressed gas to sweep clean each space that is created between the anvil portion and each cutting blade by movement of said each cutting blade to its lateral extrusion position, the release being in response to and in synchronism with the creation of each such space.

In preferred embcdiments, the release of the sweeping gas within the space to be swept in response to and in synchronism with the creation of the space is achieved by arranging for the duct means to be sealed against substantial discharge, at the position of each blade, by the blade itself whenever the blade is in its cutting position.

The duct means preferably comprises a plurality of gas distributor outlets formed in the anvil portion or in the cutting blades, each gas outlet being disposed adjacent the edge of a cutting blade and being substantially sealed by face to face contact between the anvil portion and S" the cutting blade whenever the blade is in Its cutting position.

see 9*o The gas distributor outlets may comprise open grooves in faces of the anvil portion or the cutting blades, with further supply grooves or ducts providing communication between the distributor grooves and a supply of compressed gas, Alternatively, supply ducts may be drilled or otherwise S provided in the anvil portion or in the cutting blades, the supply ducts 20 feeding outlet distributor ports In the faces of the anvil portion or the cutting blades, In a particularly preferred embodiment, the clinching die comprises a rotatable die assembly comprising an anvil wheel sandwiched between two cutting wheels, each cutting wheel having a plurality of radially projecting cutting blades at its periphery, the die assembly being adapted to co-operate with a rotatable punch wheel.

Brief Description of the Drawings A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an end view of a rotary punch and die set incorporating a clinching die in accordance with the invention; Figure 2 is an enlarged view of the clinching region of the rotary punch and die set of Figure 1; Figure 3 is an enlarged side view of the clinching region of the rotary punch and die set of Figure 1; Figure 4 is an end view of an anvil wheel of the clinching die of the punch and die set of Figure 1: Figure 5 is an enlarged view of the peripheral edge of the anvil wheel of Figure 4; Figure 6 is a side view of one face of the anvil wheel; Figure 7 Is a side view of the opposite face of the anvil wheel; and Figure 8 is a section on the line VIII-VIII of Figure 7.

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Detailed Description of the Drawings Referring to the drawings, a rotary punch and die set comprising a punch assembly 12 and a die assembly 14 is shown which is adapted to produce rows of spaced apart clinches extending along a roll-formed member 16 as the last operation of the roll-forming process.

The die assembly 14 comprises a pair of dies 17, each comprising an anvil wheel 20 sandwiched between, and co-axial with, two cutting wheels 21 and 22. The anvil wheel 20 is a flat sided disc and the internal surfaces 23 and 24 of the cutting wheels 21 and 22 contacting the respective side faces 25 and 26 of the anvil wheel 20 make face to face cont,-t therewith. The anvil wheel 20 is usually thicker than the cutting wheels 21 and 22, and is smaller in diameter than the cutting wheels 21 and 22 by an amount that is substantially equal to twice the total thickness of the laterally extruded material in the finished clinch, Thus, the cutting wheels 21 and 22 project radially beyond the periphery of the anvil wheel 20 by an amount substantially equal to the total thickness of the laterally extruded clinch material, The circumferential edge margins of the cutting wheels 21 and 22 are cut by a series of equiangularly spaced, radially extending slits 27, so as to convert those margins into a plurality of radially projecting cutting blades 28.

In use, a punch wheel 18 of the punch assembly 12 having a plurality of radially projecting punch elements 30 co-operates with each die 17. The punch wheels 18 and the dies 17 are mounted for powered rotation about parallel axes, such that the tips of the punch elements which have an axial thickness substantially equal to that of the anvil wheel 20, and the edges of the cutting blades 28, move in mutually tangential circles. The punch wheels 18 and the sets of die wheels 21 and 22 are angularly related so that each punch element 30 is aligned with a corresponding oair of cutting blades 28 at the position of "contact" of those circles.

Thus, if two or more overlapping sheets 31 and 32 of appropriate overall thickness are passed between the punch wheels 18 and the sets of die wheels 20, 21 and 22, each punch element 30 and its corresponding pair of the cutting blades 28, as they come into contact with the sheets 31 and 32, shear through the opposite edges of small rectangular portions of the sheets while the punch element 32 displaces those portions into contact with the rim 34 of the anvil wheel Immediately thereafter each punch element 30 squeezes the displaced portions against the peripheral rim 34 of the anvil wheel 20 to effect lateral extrusion thereof. As this occurs, the corresponding cutting blades 28 are caused to resiliently spring apart by the spreading of the displaced portions as they are laterally extruded. The rim 34 of each anvil wheel 20 has a slightly greater circumference at its centre than at its edges, as shown in Figure 5, to assist in spreading the displaced portions of the sheets.

In accordance with this embodiment of the Invention, the shaft on which the dies 17 are mounted has an air supply drilling extending axially along the shaft from one end thereof to a radial drilling that opens to the shaft surface at the position of the die, Compressed air from a conventional source is fed Into that drilling by conventional means.

Each side face 25 and 26 of each anvil wheel 20 Is grooved, In general, the groove pattern on each side of the anvil wheel 20 may conveniently comprise a respective circular bus groove 35, 36 co-axial with the anvil wheel, a plurality of radial distributor grooves 37, 38 extending from the bus groove 35,36 to near the outer periphery of the anvil wheel 20 and a supply groove 39,40 extending from the inner periphery of the anvil wheel 20 to the bus groove 35,36. Each distributor groove 37,38 is provided underlying a respective cutting blade 28 of the cutting wheel 21,22 on the side of the anvil wheel 20 in question. Each supply groove 39,40 receives air from the drilling in the shaft. We say this is the groove pattern "in general" because it may be distorted as needed to avoid bolt clearance holes 42 for bolts securing the cutting wheels 21,22 to the anvil wheel 20, key ways 44 for the affixture of the wheels 20,21,22 to their shaft and any other intruding constructional details, without detriment. For example, as shown in Figure 7, the circular bus groove 36 is disposed radially inwardly of the bolt clearance holes 42 and further arcuate grooves 41 are provided which connect the distributor grooves 38 in the region of the bolt holes, The grooves 35 to 41 in the side faces 25,26 of the anvil wheels 20 may be open grooves as they are covered by the relevant cutting wheel 21,22 so that leakage is prevented, However, each time a cutting blade 28 Is displaced by the laterally extruded sheet material air may escape from the distributor 37,38 groove underlying that blade 28, This sweeps clean the space between the displaced blade 28 and the anvil wheel 20 at each operation of each blade 28, so attaining the object of the Invention without excessive usage of air and wlthout the production of objectionable noise, It will be appreciated that other air supply ducts may be used, for example they may comprise similar grooves in the faces of the cutting wheels that contact the anvil wheel. They may comprise drillings within the anvil wheel feeding outlet ports underlying the respective cutting blades.

It will also be appreciated that quite substantial changes may be needed to apply the irnvention to other types of dual function clinching dies, for example simpler dies for use in conjunction with a reciprocating punch, or punch and die sets wherein the die parts carrying the cutting edges are mechanically retracted or displaced, as against being resiliently sprung aside, In every case however the invention requires the sweeping gas to be released only in consequence of, or in synchronism with, the movement of those die parts,

Claims (14)

1. A dual function clinching die comprising an anvil portion and at least two cutting blades flanking the anvil portion and which are movable from i, cutting position adjacent to the anvil portion to a lateral extrusion spaced from the anvil portion; wherein the die further comprises eia'ing means comprising duct means for the release of compressed gas to ;,Neep clean each S space that is created between the anvil portion and each cutting blade by movement of each cutting blade to its lateral extrusion position, the release being :i in response to and in synchronism with the creation of each space.

2. A clinching die according to claim 1, wherein the duct means, at the position of each blade, is sealed against substantial discharge by the blade itself whenever the blade is in its cutting position. 9

3. A clinching die according to claim 2 wherein the duct means comprises a plurality of gas distributor outlets, each of which is disposed adjacent the edge of .j a cutting blade and which is substantially sealed by face to face contact between the anvil portion and said cutting blade whenever the blade is in its cutting position,

4. A clinching die according to claim 3 wherein the gas distributor outlets are provided in faces of the anvil portion which contact surfaces of the cutting blades in the cutting position of each blade, A clinching die according to claim 3 wherein the gas distributor outlets are provided in the surfaces of the cutting blades which contact faces of the anvil portion in the cutting position of each blade.

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6. A clinching die according to claim 4 wherein the gas distributor outlets comprise open grooves in said faces of the anvil portion which, in the cutting position of each blade, are contacted by the blades, to prevent substantial leakage of gas.

7. A clinching di) according to claim 1 wherein the anvil portion comprises a rotatable anvil wheel sandwiched between two cutting wheels, each cutting wheel having a plurality of radially projecting cutting blades at its periphery. 00

8. A clinching die according to claim 7 wherein the duct means comprises a plurality of gas distributor outlets provided in faces of the anvil wheel or of the 0* cutting wheels, each distributor outlet being located adjacent the cutting edge of a respective one of said cutting blades and being substantially sealed by face to face contact between the anvil wheel and the cutting wheels when Its respective blade is in its cutting position. 0

9. A clinching die according to claim 8 wherein the duct means further comprises gas supply ducts connected to a supply of compressed gas and communicating with said gas distributor outlets.

A clinching die according to claim 9 wherein the gas distributor outlets and gas supply ducts are provided by grooves in faces of the anvil wheel,

11. A clinching die according to claim 9 wherein the gas distributor outlets and gas supply ducts are provided by grooves In faces of the cutting wheels.

12. A clinching die according to claim 10 wherein the grooves include a plurality of radial distributor grooves disposed near the outer periphery of the anvil wheel, a circular bus groove communicating with the radial distributor grooves a r-"i P-~C I and a supply groove extending from the Inner periphery of the anvil wheel to the bus groove.

13. A clinching die substantially as hereinbefore described with reference to any one or more of the accompanying drawings,

14. A punch and die assembly Incorporating a clinching die In accordance with 00any one of the preceding claims, .0 0* 0* 0 :0 *a* 0 Applicant Attorney BHP STEEL (JLA) PTY. LTD Date 21 October 1996 ROBERT G. SHELSTON F.I.P.A.A. of CARTER SMITH BEADLE I I ABSTRACT CLINCHING DIE A dual function die assembly (14) is providej for co-operation with a punch assembly (12) to produce a row of spaced apart clinches in overlapping sheets (31 and 32) of a roll formed member The clinching die assembly (14) includes at least one anvil wheel sandwiched between cutting wheels (21 and 22) which have cutting blades (28) at their pe;rpheries, A plurality of distributor grooves (37,38) are provided in the faces (25,26) of the anvil wheel (20) which contact internal surfaces (23,24) of the respective cutting wheels (21,22). The distributor grooves (37,38) are connected to a supply of compressed air and are normally sealed by the face to face contact between the anvil and the cutting wheels, but when a cutting blade (28) is displaced by lateral extrusion of sheared, displaced portions of the sheets, air can escape from the distributor groove (37,38) underlying that blade to sweep away any chips of severed material from the space between the displaced blade (28) and the anvil wheel