JPS5816283B2 - How to make the most of your time - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves filling different types of metal powder layers into one press tool and compressing each time before filling the next metal powder layer, so that each layer has a different composition. The present invention relates to a method and apparatus for producing a molded article for electrical contacts having high load resistance.

Such a method is known from German Patent Application No. 1458477.

The multilayer moldings required for the production of electrical contacts capable of withstanding high loads are compacted layer by layer, subsequently sintered and impregnated with metals with higher electrical conductivity.

In order to obtain various space filling densities in the layered sintered structure, the individual layers constituting the compact are compressed with different compression forces.

When manufacturing a multilayer molded body as described above, generally a press tool consisting of an upper ram, a lower ram, and a matrix is fixedly placed on a press table.

Between the individual strokes of the press, a filling device is moved over the master mold to fill it with a corresponding layer of metal powder.

In that case, it is inevitable that the leaked powder generated on the press table will be mixed into the next metal powder layer.

This has the undesirable result of intermixing of dissimilar metal powder layers.

Furthermore, in presses that are performed sequentially in a short period of time, it is impossible to adjust the press pressure to be different for each stroke.

In general, the hydraulic cylinders of a press can only be adjusted to a constant press pressure between the minimum and maximum pressure of the corresponding hydraulic device.

For this reason, mechanical presses are used in which the stroke of the press can be adjusted and the individual metal powder layers are compacted to a certain height.

However, when compressing individual layers to a certain height, the press pressure is not kept constant, so errors in filling the metal powder layer can result in various compacts (variations in density within the individual layers). be.

Due to the occurrence of such density fluctuations, it becomes impossible to appropriately determine the various conditions for the subsequent sintering and sinking of the compact.

Variations in density also affect the degree of space filling of the impregnated metal, which can lead to variations in contact quality with respect to firing ratio and conductivity.

An object of the present invention is to provide a method for producing molded bodies having different compositions for each layer, such that the individual layers are separated in an orderly manner and there is no density variation within the individual layers of various molded bodies. It's about doing.

This purpose, according to the invention, is to fill one press tool with layers of different metal powder, each in a predetermined working position, and in each case before filling with the next metal powder layer, in each case at a different working position. A number of press tools corresponding to the number of these operating positions are moved cyclically step by step from one operating position to the next, and simultaneously in all operating positions. This is achieved by filling, compressing or extruding the finished molded body.

Since the filling process and compression process are spatially separated,
The leakage powder that occurs after each filling process can be completely removed, thus making it possible to separate the metal powder layer in an orderly manner.

In the operating position for the compaction process, a compaction cylinder is arranged whose compaction force is adjusted to the optimum compaction density of the respective metal powder layer.

By performing all the filling and compression steps at the same time, - the cycle time is reduced from the total time of the entire operating process to the maximum operating process time, the press tool movement time for each process, and the time needed to extrude the finished compact. It is reduced to the sum of the time required for

By adjusting the individual compression forces, it is also possible to define the interlocking depth of the individual metal powder layers.

By spatially separating the filling process, uniform filling,
It is therefore also possible to narrow the tolerances of the plane parallelism of the individual layers of the molded body.

It is known in the art for the production of two or more tablets to have a number of press tools successively pass through operating positions on a circular track for filling with different press materials.

In between these operating positions, the upper ram of the press tool is pressed down following a cam that raises and lowers this ram until each layer of the respective tablet is compressed to a constant height.

Since a constant density of the layers of the various tablets is not a problem in the production of tablets, such known principles cannot be applied to the production of shaped bodies for high-load-bearing electrical contacts.

The necessary changeover from compression at constant height to compression at constant pressure is difficult to implement in a continuous process.

The progressive feed of the press tool and the fixed arrangement of the working position for the compression of the individual layers make it possible for the first time to carry out the compression operation with constant pressure.

The finished molded body is advantageously extruded from a press tool in a predetermined working position.

In this case, filling, compaction and extrusion take place simultaneously in all working positions.

According to such measures, - the time per cycle is
The time required to extrude the finished molded body is further reduced.

The apparatus for carrying out the method of the present invention includes a round table arranged with a vertical rotation axis and capable of rotating step by step for each process, press tools arranged at equal intervals on the round table, and corresponding to these press tools. a pneumatically or hydraulically operated fixed device for filling and compressing layers of various metal powders or for extruding finished compacts; and stepwise movement of said round table from one working position to another. It is preferable to have a drive device for this purpose.

By arranging the press tool on a round table, the individual devices for filling, compaction or extrusion can be arranged in a circular manner, which results in a considerable saving in the construction space of the overall device.

By moving not only the mother mold but also the upper and lower rams belonging to it, the slight pitching error that is inevitable when driving a round table step by step does not become a noticeable hindrance.

By providing pneumatically or hydraulically operated devices for filling and compacting the various metal powder layers or for extruding the finished compact, the susceptibility to failure of the individual devices is reduced.

In addition, the compression pressure can be kept constant during the compression of the individual metal powder layers.

It is advantageous to provide a fixed suction device between the filling device and the compaction device of the various metal layers, respectively, to remove any leaking powder.

By reusing the aspirated powder, losses of the individual metal powders can be kept very low.

Next, the present invention will be described in more detail with reference to the drawings showing embodiments of the present invention.

On the rotary round table 1 shown in FIG.
The press tools 2 to 6 are provided offset by a central angle of 2°.

Press tools 2 to 6 have operating positions F 1 and P 1
, F, l;2, F2 and A correspond to each other, and their operating positions correspond to the following steps.

Fl: Filling of the first metal powder layer, Pl: Compression of the first metal powder layer, F2: Filling of the second metal powder layer on the compressed first metal powder layer, F2: Filling of the second metal powder layer. Compression of the metal powder layer and, if necessary, recompression of the first metal powder layer. A: Extrusion of the finished compact.

The round table 1 is rotated step by step clockwise by the center angle α in each process, so the press tools 2 to 6 are at the operating position F1.
．． P1. F2. P2 and A are passed through in sequence in a cyclic manner.

Since all the processes are carried out simultaneously in the press tools 2 to 6, the completed molded body is discharged at the operating position A after each process.

Figure 2 is the same as the one in Figure 1:F1'ii','
A press tool consisting of a matrix 7, an upper ram, and a lower ram 9 is placed on the rotary round table 1.

The guide elements of the upper ram 8 or of the lower ram 9, which are fixedly connected to the rotary table 1, are not shown.

A fixedly arranged filling device 10 is provided between the upper ram 8 and the lower ram 9, which feeds a first metal powder layer 12 into the mother die 7 of the press tool via its filling tube 11. is filled.

□゛FIG. 3 shows the compression molding of the first metal powder layer in the working position and 1 of FIG. After rotating the round table 1 by a certain amount, the metal powder layer 12 is compressed by a constant compression force of the hydraulic compression cylinder 13.

In this case, the hydraulic compression cylinder 13 is pressed against the upper ram 8, whereas the lower ram 9 rests on the lower ram support 14.

FIG. 4 shows the filling of the second metal powder layer in the operating position F2 of FIG.

When the round table 1 is further rotated through an angle of 72° so that the first metal powder layer 12 is compressed, the master mold 7 is under the filling device 15.

A second metal powder layer 17 is filled onto the compressed first metal powder layer 12 in the matrix 7 via a filling tube 16 .

FIG. 5 shows the compaction of the second metal powder layer 17 in the first working position P2.

After filling the second metal powder layer 17 and rotating the round table 1 through an angle of 72°, the second metal powder layer 17 is compressed by a constant compression pressure of the hydraulic compression cylinder 18 .

In this case, the hydraulic compression cylinder 18 is pressed against the upper ram 8, whereas the lower ram 9 rests on a lower ram support 19.

FIG. 6 shows the extrusion of the completed molded body in operating position A of FIG.

When the second metal powder layer 17 is compressed and the round table is further rotated by an angle of 72°, the lower ram 9 is moved to the lower ram base 20.
be placed on top.

This causes the lower ram 9 to be pushed up by such a width that the finished molded body is extruded from the matrix 7.

As shown in FIGS. 2, 4 and 6, in the working positions F1, F2 and A, a constant maximum /J. It is necessary to provide an interval.

On the other hand, this spacing is such that when the upper ram 8 descends, its pressing shaft is not yet compressed.
7 from the matrix 7, the working positions qp1 (FIG. 3) and F2 (FIG. 5) before the operation of the hydraulic compression cylinder 13 or 18 must be as small as possible.

The upper ram 8 is therefore guided in a rigid cam track in such a way that it assumes an upper position in the operating positions F1, F2 and A, and a lower position in the operating positions P1 and F2.

If a suitable notch is provided in this cam track, in the operating positions P1 and F2, when the hydraulic compression cylinder 13 or 18 is operated, the upper or lower side 0? , the ram 8 can be lowered deeper.

, 5

[Brief explanation of drawings]

FIG. 1 is a drawing schematically showing the arrangement of a press tool and operating positions in the case of manufacturing a 1.2-layer molded body, and FIGS. 2 to 6 are cross-sectional views of the press tool at each operating position. 1...Round table, 2 to 6...Press tool, 7...Mother die, 8...Upper ram, 9.
...Lower ram, 10°15...Filling device, 11,16...Filling pipe, 12°17...
...Metal powder layer, 13.18...Hydraulic cylinder, 14,19.20...Ram stand.

Claims (1)

[Scope of Claims] 1. Filling a press tool with different layers of metal powder, each in a predetermined working position, each time applying a constant compression in a different working position before filling the next metal powder layer. compressing with force, moving a number of press tools corresponding to the number of these working positions step by step cyclically from one working position to the next, filling all working positions simultaneously, A method for producing a molded body for a high load-bearing electrical contact having a different composition for each layer, the method comprising compressing or extruding a completed molded body. 2. A round table arranged with a vertical axis of rotation and capable of rotating step by step for each process, press tools arranged at equal intervals on this round table, and filled with various metal powder layers corresponding to these press tools. , comprising a pneumatically or hydraulically operated fixed device for compressing or extruding the finished molded body, and a drive device for moving the round table step by step from one operating position to another. Apparatus for carrying out the method according to claim 1, characterized in that: