Patent Application
20140096584
The invention relates to forming techniques used in progressive metal formers.
Forging or forming machines have long been used to shape cylindrical blanks into more complex shapes. A common forming method involves upsetting or coning dies in which a blank is axially compressed to expand it radially. There are limits to the amount of radial expansion that can be obtained in a single forming blow without unacceptable buckling of the blank. Consequently, in a progressive former, several stations may be required to produce a desired radially extending shape. On the other hand, some parts may require a reduction in area using an extrusion technique but, again, such processes have physical limits, as recognized in the industry. Still further, to form some irregularly shaped parts using customary processes, it can be necessary to trim a large volume of material from the blank so that the resulting scrap adds significant costs to a process.
The invention involves lateral extrusion of a blank in a workstation in a progressive forming machine. The invention allows various metal parts to be shaped in fewer stations than has been required in the past, can produce parts with lateral extensions exhibiting a high reduction in area and/or a finished thickness and, can reduce a percentage of scrap by eliminating or reducing the amount of material required to be trimmed from asymmetric and/or accircular parts.
The invention employs a spring biased slidable tool. During sliding movement, a tool cooperating with an opposed tool is arranged to form a sideways extrusion. The spring biased sliding tool allows the final part of a ram stroke to displace blank material through a lateral aperture bounded by the sliding tool and the opposed tool. The spring is arranged to hold the tools in fixed relation during this blank extrusion step against forces developed in the blank.
The sliding tool can be mounted on either the ram or the die breast of the progressive forming machine. The spring allows the slidable tool to recede on the part of the machine on which it is mounted while the ram is approaching front dead center (FDC) and displacing blank material through the lateral extrusion aperture.
At the second workstation 17, the blank 26 is uniquely shaped with a sideways or lateral extrusion step shown in
The cutoff, square-up and hole punching operations and tooling to accomplish the same at the respective cutoff, first and third stations are generally conventional and need no further explanation for an understanding of the invention.
The sequence of movement of the tooling at the second station 17 follows the transfer of the blank 26 to this station (and the simultaneous transfer of the previous blank to the succeeding station 18). With the blank 26 transferred, the ram 12 advances towards the die breast 13 carrying the tool assembly 32 biased by the spring 47 and lever 46 so that these tool parts lead the ram. Prior to FDC, the face of the tool assembly insert 37 engages the die 31. Together the cavity of the insert 37 and die 31 define the shape of the blank 26 to be produced at this station 17. The blank shape is depicted in
The cavity 38 has a cylindrical bore 51 of a diameter sufficiently large to receive the blank 26 shaped at the first station 16. The face of the tool insert 37 mates with the die 31 by fitting tightly against the flat face of the die. At one side of the bore 51 is a rectangular aperture having a boundary partially formed by the face of the die 31. With the faces of the tool insert 37 and die 31 held tightly together by the high pressure lever 46 to prevent escape of material of the blank 26 at their interface, the ram 12 advances towards the die breast 13 driving the punch pin 39 into the blank.
Initially, with the punch pin 39 and sleeve 41 moving in unison with the ram 12, the blank 26 back extrudes to fill a space 54 (
Preferably, the aperture 52 is slightly smaller in cross-section than a space 57 that receives and generally confines the extruded material. Stated otherwise, the receiving space 57 is provided with a slight dimensional relief, i.e. made slightly larger in cross-section than the aperture 52. This relief reduces resistance to flow of blank material through the space 57. An end of the receiving space or channel 57 can be closed (apart from suitable air and lubricant venting) to shape the extremity of the extension 56 or can be open. The receiving space 57 is primarily formed in the insert 37 but has a part of its boundary or side formed by the die 31.
The ram 12 retracts; when the retraction exceeds the slide movement of the punch assembly 32, the punch assembly carried by the ram 12 retreats from the die 31 to eventually release the blank 26 for transfer to the third station 18. The punch assembly sleeve 41, in the illustrated arrangement, can be used to hold the blank 26 in place on the flat face of the die 31 until it is under control of the transfer mechanism 21. At the third station 18, the lateral extension 56 can be further shaped;
The extrusion process is distinguished over a traditional upset or coning operation in that the material of a blank being forced into the extruded shape including that contacting, but slipping over, the confining and shaping die and punch tools is all displaced by succeeding increments of blank material. In an upset or coning, the blank material at the confining punch and die surfaces does not slip across these surfaces.
The lateral or sideways extrusion technique of the invention represented by the foregoing example, can offer many benefits over traditional forming steps. An extruded detail can, as illustrated, be limited to a fraction of the circumference of the blank thereby reducing or eliminating the need to trim material from a workpiece that is asymmetrical or accircular in finish form. The aperture 52 can be dimensioned to produce a lateral extension 56 with a finished thickness or cross section. A workpiece or part can be produced with more than one lateral extension at multiple locations around the circumference in a single forming station. The aperture can extend through 360 degrees around the axis of the original blank to create a full peripheral rim or flange. The die face can have formations other than the disclosed flat to shape a part as long as the punch assembly and die cooperate to form the extrusion orifice and receiving space analogous to the space 57 and allow the extruded extension to be released after it is formed. The spring biased sliding tool can be mounted on the die breast or bolster 13 rather than in the illustrated arrangement where it is mounted on the ram 12.
It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.
