FIELD OF INVENTION

This invention relates to dies and particularly split dies for producing compacted parts out of powder material having an undercut, and more specifically relates to a device having an upper die, lower die, at least one upper punch associated with the upper die, and at least two lower punches associated with the lower die for producing compacted parts out of powder material having an undercut.

Background of the Invention

Devices to compact parts out of powder material for sintering are well known to those persons skilled in the art. In some cases, the compacted part has an undercut which prevents removal of the part or blank from the dies by linear or axial displacement.

Tool sets with split dies are known in powder material compaction to press parts into shapes that have an undercut in the compacting direction.

For example, United States Patent No. 3,773,446 teaches a device for moulding parts to be sintered by compressing powdered material held between a fixed die and moveable die. A pair of punches extending through the dies compresses the powder material. A pressure plate operated by the punch extending through the moveable die engages the moveable die and is also locked to the fixed die during the compression so as produce a part having an undercut.

Moreover, United States Patent No.3,752,622 teaches a device for moulding blanks with undercut parts to be sintered by compaction of powder material.

The prior art teaches that both parts of the die are tied together while filling with a feed box that moves across the top of the dies for purpose of filling the cavity with powdered material. After compaction the upper part of the die moves away together with

the top punch to eject the part.

One of the disadvantages of the known systems as referred to above relates to the fact that the upper part of the die has to be tied mechanically to the lower part of the die and the upper punch in an alternating mode, thus making a complicated tool rig necessary.

It is therefore an object of this invention to provide a device that is simpler to construct and more efficient to operate than heretofore known by the prior art.

It is another object of this invention to provide a tool system with a split die where both parts of the die remain tied to one part of the rig during the entire cycle.

It is an aspect of this invention to provide a device to compact parts with an undercut out of powder material comprising: an upper die moveable relative a lower die; at least one upper punch associated with said upper die for relative movement therebetween; at least two lower punches associated with said lower die for relative movement therebetween; said lower punches defining a lower cavity with said lower die for filling with said powder material when said dies are in an open position; said upper die contacting said lower die in a closed position for movement of one of said lower punches toward said upper die so as to transfer said powder material toward said upper die and then to compact said powder material between said upper and lower punches with said dies in said closed position so as to produce said part with said undercut; said dies moveable to an eject position for ejection of said compacted part.

It is a further aspect of this invention to provide a device to compact parts with an undercut out of powder material in a press having an upper and lower die: an upper die moveable relative a lower die between an open closed and eject position; structure for relative movement between said dies; at least one upper punch associated with said upper die for relative movement therebetween; structure for relative movement between said upper die relative said upper punch; at least two lower punches associated with said lower die for relative movement therebetween; structure for relative movement

between said lower punches relative said lower die; said lower punches defining a lower cavity with said lower die for filling with said powder material when said dies are in said open position; whereby said upper die contacts said lower die in said closed position for movement of one of said lower punches towards said upper die so as to transfer said powder material toward said upper die and then to compact said powder material between said upper and lower punches with said dies in said closed position so as to produce said compacted part with said undercut; structure for relative movement between said lower punches relative said other lower punches; said dies moveable to an eject position for ejection of said compacted part.

It is a further aspect of this invention to provide a method of producing a compacted part out of powder material with an undercut by utilizing a press having an upper die, a lower die, at least one upper punch associated with said upper die, and at least two lower punches associated with said lower die, comprising the steps of: positioning said upper die in spaced relationship with said lower die to an open position; whereby said upper punch defines an upper cavity with said upper die, and one of said lower punches is disposed in a lowest position relative said lower die and said other lower punch is disposed in a lowest position relative said one of said lower punches so as to define a lower cavity for filling with said powder material when said dies are in said open position; moving said upper die and said upper punch with said upper cavity relative said lower die whereby said upper die contacts said lower die and seals said cavities, moving said other lower punch relative said one of said lower punches so as to transfer powder material to said upper cavity; compacting said powder material between said upper and lower punches in said dies, as to produce said compacted part with an undercut; moving said dies to an eject position so as to eject said compacted part.

It is a final aspect of this invention to provide a device to compact parts out of powder material with an undercut consisting of a tool rig in a press with an upper die, lower die, at least one upper punch associated with said upper die, and at least two lower punches associated with said lower die wherein said upper die is mounted with a drive system to an upper ram of said press, and is moveable by said drive system relative said upper ram so that after filling of a cavity created by said lower die and said lower punch

and after closing of said cavity with said upper die and said upper punch, said powder material is transferred by moving one of said lower punches with a drive system upwardly toward said upper die and after compaction said upper die moves upwardly with said upper ram for ejection of said compacted part.

Drawings of the Invention

These and other objects and features of the invention shall now be described in relation to the following drawings.

Figure 1 is a representative view of the device showing the upper and lower dies and upper and lower punches.

Figure 2 is a representative view of the device showing the compacted part having different levels on the lower surface.

Figure 3 is a schematic view of another embodiment of the invention showing the various two upper and three lower punches.

Figure 4 is a front elevational view of the press.

Description of the Invention

Like parts shall be given like numbers throughout the invention.

A device 17 is utilized to compact parts 13 out of powder material with an undercut IS in a press 30. The press 30 is well known to those persons skilled in the art and includes an upper ram 32, lower ram 34 and press table 36 which is fixed relative the frame of the press 30.

Figure 1 illustrates the device 17 which includes the top or upper die 1, at least one top or upper punch 2, a bottom or lower die 3, and at least two bottom or lower punches 4 and 5.

The top die 1 has a drive system 6 which may comprise a hydraulic cylinder mounted to the upper ram 32 of a press 30. Accordingly, the top die is moveable relative the upper ram by means of the device system 6. The top punch 2 is mounted on the upper ram 32 while the bottom die 3 is driven by the lower ram 34 of the press 30. Moreover, at least one of the bottom punches 5 has a drive system which may consist of a hydraulic cylinder 38 mounted stationary relative to the frame 36 of the press 30.

The upper punch 2 is associated with the upper die 1. In particular, the upper die 1 has a hole 8 for receiving upper punch 2 for slidable relative motion therebetween.

The lower punches 4 and 5 are mounted for relative slidable movement with the lower die 3. In particular, lower die 3 includes a hole 9 to receive punches 4 and S for relative slidable movement therebetween. Furthermore, the lower punch 4 includes a hole 10 for slidably receiving lower punch 5. The lower punch 5 moves relative the lower punch 4 between the lowest position shown in Figure la and the closed position shown in Figure lb. The cavity 7 includes a volume 11 which is defined by the space created between the slidable relative movement of punch 5 relative punch 4 from the position shown in Figure lb to that shown in Figure la.

The upper die 1 and lower die 3 are adapted for relative movement between an open position as illustrated in Figure la and a closed position as shown in Figure lb. In the open position, a feed box (not shown) moves over the cavity 7. The cavity 7 is defined by the space between the lower die 3 and the lower punches 4 and 5 when the lower punch 4 is in its lowest position relative the lower die 3, and where the other lower punch 5 is in its lowest position relative the lower punch 4 as shown in Figure la. The lower punch 5 is moved far enough down or in its lowest position that enough powder 12 can be stored for the compaction of the part 13.

After filling of the cavity 7 the upper ram is moved down until the upper die 1 is touching the lower die 3 as shown in Figure lb for sealing of the cavity 7. The lower die 3 and lower punch 4 have not moved between the positions shown in figure la and lb.

Thereafter the moveable lower punch 5 travels upward so as to transfer the powder 12 from the volume 11 into the cavity 14 in the top die 1. The upper cavity 14 is defined by the upper die 1 and upper punch 2. The upper die 1 moves relative the upper punch 2 by means of the hydraulic cylinder 6 as best shown in figure Id.

Figure lb illustrates that the upper cavity 14 is offset from the lower cavity in a direction perpendicular to the movement of the upper die 1 relative the lower die 3 (in other words the compaction direction), so as to produce said part 13 with an undercut 15.

The compaction is shown in Figure lc and is accomplished by moving the upper ram.32 and both dies 1 and 3 with a suitable speed relationship downward. After compaction the part is ejected by withdrawing the top die 1 upward and the lower die 3 downward as shown in figure Id.

It is possible to also have a stationary bottom die if the bottom punches are mounted to the lower ram of the press and are used for counter pressing and ejection.

Figure Id shows the ejection of the part 13 when the dies 1 and 3 are in an eject position. The part 13 has an undercut 15.

The embodiment illustrated in Figure 1 shows the compaction of a single level part 13 with an undercut 15. The invention is not limited thereto but can also be used for multi-level parts with an undercut by introducing necessary additional top and bottom punches. For example, Figure 2 illustrates a part 13 having multiple levels which is created by the each of punches 4 and 5 being at different levels. In such case the device and method shown herein is more advantageous since the bottom punch which transfers the powder into the top die can at the same time form one of the bottom levels of the part.

Figure 3 illustrates another embodiment of the invention having several upper punches 50 and 52. Upper punch 52 could be stationary and upper punch 50 could be moved by suitable hydraulic cylinders. Moveover, Figure 3 illustrates several lower punches 56, 58 and 60. Numeral 51 shows the pitch diameter of the tooth form within the punches and respective dies.

In order to conduct all necessary movements during the cycle with suitable precision and speeds and timing, a hydraulic press with closed loop controls is preferably used, although the invention is not limited thereto.

The drawings illustrate the withdrawal principal which means that after compaction the lower die is withdrawn to eject the part. However the invention described herein is also applicable for the counterpressing principle in which case the bottom die is stationary relative the press and all the bottom punches are mounted to the lower ram (including the drives to achieve relative movements between the bottom punches, if more than one bottom punch), so that after compaction the bottom punches will be moved further through the bottom die by the lower ram in order to eject the part.

Although the preferred embodiment as well as the operation and use have been specifically described in relation to the drawings, it should be understood that variations in the preferred embodiment could be achieved by a person skilled in the trade without departing from the spirit of the invention as claimed herein.