BACKGROUND OF THE INVENTION
This invention relates in general to an apparatus for forming a workpiece to have a desired shape. In particular, this invention relates to an improved die assembly for use in such an apparatus for forming a workpiece that prevents the formed workpiece from being undesirably retained on the die assembly.
A wide variety of apparatuses are known in the art for forming workpieces to have a desired shape. For example, mechanical presses are well known apparatuses that are commonly used to manufacture a wide variety of workpieces including, for example, relatively large or thick-walled workpieces such as side rails, cross members, and other components for vehicle frame assemblies. A typical mechanical press includes a stationary portion (typically referred to as a bed) having a first die section of a die assembly secured thereto, a movable portion (typically referred to as a ram) having a second die section of the die assembly secured thereto, and an actuating mechanism for selectively moving the ram toward and away from the bed. When the ram is moved toward the bed, the first and second die sections of the die assembly engage the workpiece and exert forces thereon to mechanically form it into a desired shape. When the ram is moved away from the bed, the first and second die sections are moved apart from one another to allow the formed workpiece to be removed and the next workpiece to be formed to be inserted.
It is often desirable to form workpieces to have relatively complex shapes that can include, for example, stiffening features or mounting bosses at various locations. These relatively complex shapes may, after formation, cause portions of the formed workpiece to be clamped or otherwise retained on portions of the die assembly. Such retention of the formed workpiece on the die assembly is usually undesirable because it can inhibit the removal of the formed workpiece from the die assembly, thereby increasing the amount of time and effort necessary to complete the forming cycle. Thus, it would be desirable to provide an improved die assembly for use in an apparatus for forming a workpiece that prevents the formed workpiece from being undesirably retained on the die assembly.
SUMMARY OF THE INVENTION
This invention relates to an improved die assembly for use in an apparatus for forming a workpiece that prevents the formed workpiece from being undesirably retained on the die assembly. The die assembly includes a support clamp, a first clamp that is movable relative to the support clamp to engage a first portion of the workpiece, and a second clamp that is movable relative to the support clamp to engage a second portion of the workpiece. A forming punch is movable relative to the support clamp after the first clamp and the second clamp have been moved to form the workpiece.
Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded, perspective view, partially broken away, of a die assembly in accordance with this invention, together with a workpiece to be formed.
FIG. 2 is a sectional elevational view taken along 2-2 of FIG. 1 showing the workpiece initially installed and unclamped on the die assembly.
FIG. 3 is a sectional elevational view taken along 3-3 of FIG. 1 showing the workpiece initially installed and unclamped on the die assembly.
FIG. 4 is a sectional elevational view similar to FIG. 2 showing the workpiece partially clamped on the die assembly.
FIG. 5 is a sectional elevational view similar to FIG. 2 showing the workpiece partially clamped on the die assembly.
FIG. 6 is a sectional elevational view similar to FIG. 4 showing the workpiece fully clamped on the die assembly.
FIG. 7 is a sectional elevational view similar to FIG. 5 showing the workpiece fully clamped on the die assembly.
FIG. 8 is a sectional elevational view similar to FIG. 6 showing the workpiece after being formed on the die assembly.
FIG. 9 is a sectional elevational view similar to FIG. 7 showing the workpiece after being formed on the die assembly.
FIG. 10 is a perspective view of the die assembly and the workpiece shown in FIGS. 8 and 9.
FIG. 11 is a perspective view of the formed workpiece after removal from the die assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, there is illustrated in FIG. 1 a die assembly, indicated generally at 10, in accordance with this invention. The die assembly 10 is adapted to be supported on any conventional apparatus for forming a workpiece to have a desired shape, such as a mechanical press (not shown) as described above. The illustrated die assembly 10 includes a base 11 and a first clamp, indicated generally at 12. The first clamp 12 includes a rigid clamp 14 and a floater clamp 16. The rigid clamp 14 includes a cavity 18 that engages the floater clamp 16 for relative movement therebetween. The floater clamp 16 is resiliently supported within the cavity 18 of the rigid clamp 14. If desired, a resilient support 15 may be disposed between the floater clamp 16 and the rigid clamp 14, although such is not required. The resilient support 15 may, for example, be embodied as a fluid spring such as a conventional nitrogen-charged die spring. The resilient support 15 may alternatively be pneumatic or hydraulic in nature (such as by means of a gas or a liquid provided within the cavity 18) or may be mechanically operated, such as by means of a helical spring, a Belleville spring, a leaf spring, an elastomeric spring, and the like. The first clamp 12 also includes a second clamp 20 that operates along with the first clamp 12 to support a workpiece (such as indicated generally at 22) on portions of the die assembly 10. The operation of the first clamp 12 and second clamp 20 will be explained below.
The illustrated workpiece 22 includes a first leg 24 having an uneven profile or complex geometry that includes a stiffening channel 24a or other protruding feature, boss, fin, rib, or structure. The illustrated workpiece 22 also includes a second leg 26, which is shown as an extending side from the first leg 24. As will be explained in detail below, the second leg 26 will be formed by the die assembly 10 to have a desired shape. The first leg 24 of the illustrated workpiece 22 has three locating apertures 28 formed therethrough, although any number of such locating apertures 28 (or none at all, if desired) may be provided.
The illustrated locating apertures 28 are adapted to be engaged by respective movable pin assemblies 30. Each of the movable pin assemblies 30 is supported on and extend beyond an upper surface of a support clamp 32. The structure and operation of the support clamp 32 and the movable pin assemblies 30 will be explained below.
The illustrated support clamp 32 is supported on the base 11 for lateral movement relative thereto for selective engagement with the second leg 26 of the workpiece 22. However, the support clamp 32 may be supported for any desired movement relative to the base 11. The illustrated support clamp 32 includes at least one pin slot 34 that engages the movable pin assembly 30. The illustrated pin slot 34 is an elongated slot that allows the support clamp 32 to move relative to the movable pin assembly 30. The relative fit between the pin slot 34 and the movable pin assembly 30 provides a sufficient locating tolerance to orient the workpiece 22 within the die assembly 10. The support clamp 32 may include a cam follower 36 that cooperates with a cam actuator 38 to effect the selective movement of the support clamp 32 relative to the base 11 in the manner described below. Alternatively, the support clamp 32 can be moved relative to the base 11 by any desired mechanism. For example, the support clamp 32 can be moved relative to the base 11 by means of a hydraulically driven ram, a reciprocating rod and clevis, an oscillating actuator, a linear motor, a rack and pinion drive, and the like.
A forming punch 40 is supported on the base 11 for movement relative thereto. The forming punch 40 may be moved by a cam assembly 42, which may be embodied as any device that can move the forming punch 40 in order to deform the workpiece 22 as desired. The cam assembly 42 may be similar to the clamping actuator examples mentioned above. The forming punch 40 includes a leading edge 44 that cooperates with a forming recess 46 provided in the support clamp 32. The cooperating leading edge 44 and the forming recess 46 are moved across the base 11 from an opened position, shown in FIGS. 6 and 7, to a closed position, shown in FIGS. 8 and 9. The closed position creates a cavity 48, shown in FIGS. 8 and 9, that defines the general shape of the second leg 26 to be formed.
Initially, as shown in FIGS. 2 and 3, the die assembly 10 is disposed in the opened position such that the workpiece 22 can be loaded onto the movable pin assemblies 30. Each of the movable pin assemblies 30 includes a pin nose 50 that extends through the locating aperture 28. Each pin nose 50 is supported on an offset arm 52, although such is not required. The offset arm 52, or alternatively the pin nose 50 directly, engages a pin actuator 54 by way of an optional push rod 56. The pin actuator 54 may be embodied as any structure that can move the pin nose 50 to an extended position to allow the workpiece 22 to be loaded into the die assembly 10. In a preferred embodiment, the pin actuator 54 is a resilient nitrogen spring that is biased in an extended position. The extended position of the pin actuator 54 positions the pin nose 50 above the upper surface of the support clamp 32. Alternatively, the pin actuator 54 may be a mechanical spring, a hydraulic spring, a magnetic spring, or the like. The pin actuator 54 may, alternatively, be a hydraulic, pneumatic, or magnetic powered actuator that is force driven from the retracted position to the extended position, if so desired. The pin actuator 54 can be either fixed directly to the base 11 or secured to another point relative to the base 11 and allows the pin nose 50 to be moved to a retracted position (shown in FIGS. 4, 6, and 8) by the first clamp 12. The first clamp 12 moves the workpiece 22 against the resilient force of the pin actuator 54. The retracted position of the pin actuator 54 allows the component pre-form 22 to engage the surface of the support clamp 32.
In operation, the workpiece 22 is placed in the die assembly 10 by engaging the pin nose 50 through the locating aperture 28, as shown in FIG. 2. The workpiece 22 may initially rest on a portion of the offset arm 52, though such an orientation is not required. The support clamp 32 may also include one or more wear plates 58 (shown in FIGS. 3, 5, and 7) that support the workpiece 22. The wear plates 58 may also be adapted to reduce the coefficient of friction between the workpiece 22 and the support clamp 32. As shown in FIGS. 4 and 5, the first clamp 12 clamps the workpiece 22 onto the support clamp 32. The rigid clamp 14 is shown having a pin recess 60 that accepts the pin nose 50, if so provided. The rigid clamp 14 may have more than one pin recess 60 to accommodate the appropriate number of pin noses 50. The floater clamp 16 may also be provided with one or more pin recesses 60 if so desired. When actuated, the floater clamp 16 contacts the surface of the workpiece 22. In the illustrated embodiment, the floater clamp 16 is configured to contact the stiffening channel 24a. The floater clamp 16 resiliently reacts against the rigid clamp 14 to apply a proportional clamping force onto the workpiece 22 as the first clamp 12 moves toward the 22. The first clamp 12 contacts the first leg 24 and engages the pin nose 50 within the pin recess 60. The first clamp 12 forces the movable pin assembly 30 into the pin slot 34.
As the first clamp 12 is being brought into contact with the first leg 24 of the workpiece 22, the support clamp 32 is moved to the closed position illustrated in FIGS. 5 and 7. In the closed position, the support clamp 32 locates against the adjacent surface of the second leg 26 of the workpiece 22. The support clamp 32 is moved toward the second leg 26 of the workpiece 22 by the relative action of the cam follower 36 against the cam driver 38. The pin slot 34 moves relative to the movable pin assembly 30 as the support clamp 32 is pushed into the closed position against a portion of the second leg 26. The second clamp 20 moves toward the second leg 26 as the support clamp 32 moves toward the closed position. The movement of the second clamp 20 is illustrated as a lateral movement across the surface of the forming punch 40, though such a movement direction is not required. Alternatively, the second clamp 20 may move in the same direction as the first clamp 12 if so desired. The second clamp 20 and the support clamp 32 engage or otherwise trap and hold the second leg 26 therebetween. The movement of the first clamp 12 onto the support clamp 32 is coordinated in time with the movement of the second clamp 20 toward the second leg 26. This coordinated movement is such that the workpiece 22 is not subjected to damaging bending or twisting loads.
Referring now to FIGS. 8 and 9, when the workpiece 22 is trapped between the first clamp 12, the second clamp 20, and the support clamp 32; the cam actuator 38 (if so provided) travels past the cam follower 36 to provide an additional lock or restraint to movement of the support clamp 32 relative to the forming punch 40. The forming punch 40 is then driven by the second cam assembly 42 into contact with a portion of the second leg 26. The second cam assembly 42 continues to press the leading edge 44 into the portion of the second leg 26. The leading edge 44 folds the portion of the second leg 26 into the forming recess 46 to form a flange 62. FIG. 10 illustrates the die assembly 10 in the closed position after forming the flange 62. FIG. 11 shows a finished workpiece 64 after ejection by the movable pin assemblies 30 from the die assembly 10.
The steps to release the finished part 64 from the die assembly 10 may be conducted in the reverse order from the clamping steps described above, though such is not required. Alternatively, the load applied by the first clamp 12 may be reduced prior to retracting the leading edge 44 from engagement with the forming recess 46. This may reduce the load required to move the leading edge 44 from engagement with the flange 62. Once the leading edge 44 is pulled past the flange 62, the second clamp 20 is moved away from the remainder of the second leg 26 of the finished workpiece 64. The first clamp 12 is further retracted from contact with the finished workpiece 64 so that the movable pin assemblies 30 can articulate from the pin slots 34 and push the finished workpiece 64 out of the die assembly 10. As the movable pin assemblies 30 eject the finished workpiece 64 from the die assembly 10, automated handling equipment may be used to move the finished workpiece 64 onto the next operation. The cycle is then ready to accept another workpiece 22 and restart the forming process.
The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.
Patent Application
20100050729
