Patent Application
20210354188
The present disclosure generally pertains to a fastening apparatus and more particularly to a metal fastening die assembly.
It is well known to employ a punch and die assembly to create a clinch joint within sheet metal workpieces located therebetween. Furthermore, many conventional die assemblies are mounted onto separate die retainers or holders in order to secure the die assemblies to a frame of an actuator tool. Examples of such die assemblies and separate holders are disclosed in the following U.S. patents invented by Sawdon which are commonly owned with the present application: U.S. Pat. No. 7,694,399 entitled “Sheet Fastening Apparatus and Method” which issued on Apr. 13, 2010; U.S. Pat. No. 6,430,795 entitled “Composite Urethane Stripper for Metal Joining Apparatus” which issued on Aug. 13, 2002; and U.S. Pat. No. 5,860,315 entitled “Device for Securing Tools” which issued on Jan. 19, 1999. These patents are all incorporated by reference herein. While these devices were significant improvements in the industry, the separate external shield of the die assembly in addition to the distinct holder sometimes causes extraneously redundant components and also can add undesired extra height to the combination which may render fastening access difficult when certain workpiece shapes are encountered.
FIGS. 12-14 of commonly owned U.S. Pat. No. 5,479,687 entitled “Apparatus for Joining Sheets of Material” which issued to Sawdon on Jan. 2, 1996, shows a die retainer integral with an outer sleeve. However, the anvil cannot be removed for replacement due to wear during use. This patent is also incorporated by reference herein.
Commonly owned U.S. Pat. No. 8,650,730 entitled “Clinching Tool” which issued to Sawdon on Feb. 18, 2014, discloses a die body with a generally rectangular exterior periphery. A pair of laterally elongated die members laterally traverse toward and away from a central anvil, and there is no ability to reorient the movable die members relative to the die body. While this patent is a significant improvement in the industry, a smaller lateral packaging size would be desirable for certain workpiece uses. This patent is incorporated by reference herein.
In accordance with the present invention, a metal fastening or joining apparatus is provided. In another aspect, a single piece die guard includes an integral die shield section and an integral retainer section, wherein a die anvil can be removed, and the die shield section has a low height and a small lateral square width. A further aspect employs a generally square peripheral shape for a die shield within which is an anvil and movable die blades, which are operable to fasten or join sheet metal workpieces together in an interlocking manner. In still another aspect, a projecting and/or peripheral orientation structure is on a backside of a workpiece fastening die assembly which allows for anvil reorientation without the need to also reorient a laterally surrounding die shield and retainer. In an additional aspect, a single piece die guard includes an integral die shield section and an integral retainer section with the retainer section stepped down from and laterally extending from only one side of the die shield section, wherein a die anvil can be removed. A method of assembling a die assembly is additionally provided.
The present apparatus and method are advantageous over traditional devices. For example, the integral shield and retainer sections reduce separate parts while providing a low height profile and smaller lateral size, to more easily access workpieces. The specific shape of the present die shield beneficially provides a low height profile and smaller lateral size to more easily fasten difficult to access workpieces. Furthermore, the present design makes assembly and disassembly of the die blades and the anvil much easier. Moreover, fewer parts and multi-functionality are beneficially achieved with the present apparatus. The present assembly and method advantageously make it easier and more accurate to reorient a central anvil and/or surrounding die blades, but without the need to reorient the outer die shield and fixture. The single piece and integral nature of the die shield and retainer improve the strength of the die assembly and its mounting, in certain aspects of the present apparatus. Certain component integration and separation in various embodiments allow for the use of different and more durable materials for some parts while reducing expense for other parts; by way of non-limiting example, the integrated anvil and base may be made of a more durable metal than the less expensive metal of the integral die shield and die retainer. Additional advantages and features of the present apparatus and method can be ascertained from the following description and appended claims, taken in conjunction with the accompanying drawings.
A first exemplary embodiment of a fastening or joining apparatus 21 is illustrated in
Die assembly 35 includes a die guard having a longitudinally elongated die shield 51 and a retainer 53 laterally projecting from a side of the die shield. Die shield or housing 51 has a generally cubic shape defined by four flat, exterior and lateral faces 55 and a substantially square end 57 which contacts one of the workpieces during joining. Rounded or chamfered corners are present at the intersections between faces 55, and where end surface 57 intersects lateral faces 55, to deter tearing of the workpieces when in contact therewith. A longitudinally elongated and cylindrically shaped, internal through bore 59 extends through die shield 51. Furthermore, a single hole 61 is located within a central flat portion of each face 55 to allow dirt, oil and other manufacturing debris to exit from through bore 59.
It is noteworthy that a backside surface 63 of die shield 51 includes a stepped recess 65. Accordingly, a longitudinal height dimension, between the backside surface 63 and opposite end surface 57 at a clamping side 67, is greater than a similarly measured height dimension where die shield meets with retainer 53, due to this recess. An equilateral, three sided polygonal internal surface 69, with rounded corners, defines a U-shape for recess 65. The parallel spaced apart, internal edges of the recess define a close tolerance keying receptacle as will be discussed in greater detail hereinafter.
The die shield and retainer section are integrally machined from the same steel block as an integral, single piece. A longitudinal height H of die shield 51 is preferably 20.0-15.0 mm and more preferably 20.0 mm, while a height h of retainer 53 is preferably 10.0-5.0 mm and more preferably 5.5 mm; thus, the retainer is less than half the height of the die shield. The preferred height differential between H and h of approximately 10-5 mm is short enough to allow the die assembly to reach into small channels even those having a backbend. Nevertheless, height H may alternately be greater than the preferred range for other uses or when a deeper mounting pocket is provided. Perpendicular lateral widths W of die shield 55 are equidistant, preferably 15.0-13.5 mm and more preferably 15.0 mm. The retainer also contains an internally threaded through bore 81 with a frusto-conical or tapered countersink opening 83 on a top surface thereof. A laterally elongated chamfer 85 is machined on opposite portions of the retainer and die shield for fitting within filleted corners of the frame pocket 36. A central portion of backside 63 of retainer 53 is flat as is the opposite top side surface. The die shield and the retainer define a side view L-shape.
A threaded screw 91, with a wrench receptacle, enmeshes with bore 81 of retainer 53 and an aligned threaded hole 93 in frame 37. Furthermore, a clamp 95 compresses against side 55 of the die shield and an associated cap screw 97 secures the clamp to a threaded hole 99 in frame 37. Thus, fasteners 91, 95 and 97 removably hold die assembly 35 within pocket 36 of the machine frame.
The die components will now be described in greater detail. Die assembly 35 includes an anvil 101 bordered by two movable die blades 103 on opposite sides thereof. Workpiece-contacting distal ends 105 (see
An elastomeric and flexible biasing ring 131 laterally surrounds die blades 103 and urges them toward anvil 101. Ring 131 preferably has a generally inverted U-cross-sectional shape with an open groove in a lower surface thereof to allow its bifurcated annular walls to compress together when a joint 133 is formed between workpieces 41. An alternate biasing member is shown as a canted coiled spring 135 in
An intermediate, cylindrical die body 141 intersects neck 113 at a laterally enlarged shoulder upon which rests and rotates a bottom of proximal ends 113 of die blades 103. Furthermore, a laterally enlarged base 143 is located at a bottom of the die body section of anvil 101. Anvil 101, neck 113, die body 141 and base 143 are all coaxially aligned with each other about a longitudinal centerline 145 and are a single integral piece made of steel.
A lateral peripheral edge 147 of base 143 is polygonal and preferably square. This allows for a keying or matching shape with internal surface 69 of recess 65 of die shield 51. Therefore, the installer can first partially withdraw the die blade, anvil and ring subassembly 149 (see
The specific exemplary anvil 101, die blade 103 and punch 39 illustrated in
Moreover, the specific flat sided shape of die shield 51 advantageously allows close access of the anvil to the workpieces especially when the workpieces need to be fastening on a flange near a tightly bent main surface. Referring to
Reference should now be made to
Another embodiment of a die assembly 221 is illustrated in
Longitudinally projecting and parallel centering and orientation pins 351 and 353, respectively, downwardly extend from backside surface 347 of base 341. Centering pin 351 is coaxial with a centerline of anvil 335 while orientation pin 353 is offset spaced therefrom. Pins 351 and 353 are received within holes in the machine frame, and there may be multiple circumferentially spaced holes to optionally set orientation pin 353 in different rotational orientations, which correspondingly differently orients the anvil and die blades without the need to differently mount the die shield and retainer. This embodiment also acts with an actuator-driven punch to create an interlocking and partially severed joint between sheet metal workpieces.
Finally,
Reference should now be made to
While various embodiments have been disclosed, it should be appreciated that other variations are possible. For example, a different quantity and shape of die blades may be employed although certain benefits may not be realized. Furthermore, the ring or spring biasing component may be differently configured although some of the advantages of the present components may not be obtained. It is also envisioned that the die blades may be fixed and not movable, but certain advantages will not be observed. While it has been disclosed to mount the present die assembly into a pocket of a machine frame, it is alternately envisioned that the present die assembly can be removably attached to a flat machine, tool, fixture or robotically movable surface without a recessed pocket. Moreover, each of the components disclosed herein may have different dimensions, shapes or materials but certain benefits may not be achieved. It should also be appreciated that the terms “top,” “bottom,” “upper,” “lower,” “back,” “side,” “end” and other such phrases are merely relative terms which may vary if the parts are inverted or differently oriented. The method steps may be performed in any order or even simultaneously for some operations. The features of any embodiment may be interchanged with any of the other embodiments, and the claims may be multiply dependent in any combination. Therefore, other variations may fall within the scope and spirit of the present invention.
