DE2843694C2 - Contact punching plate made of plastic - Google Patents

Description

The invention relates to a contact punching plate made of plastic with one made of a metallic material existing embedding of a contact body as a base for an electrically driven punch knife for punching out flat objects made of leather, plastic and other punchable materials.

Contact punching plates serve on punching systems as a support for the material to be punched and at the same time as countercontacts to the punching knife. Punch knife and punch plate form a trigger circuit for the final shutdown of the Punch feed. The punching knife cuts through the material to be punched and touches the surface of the electrically conductive contact stamping plates. When the punching knife touches the contact punching plate, it closes the circuit for the end stop of the punching process with toggle function for the return stroke movement of the punch knife.

Contact punching plates made of aluminum, plates made of aluminum with insulating film pads, and Konlaktstanzplatten are known made of thermoplastics with conductive additives such as graphite and metal fiber fleece.

The disadvantages of these plates mentioned are:

Pure metal contact plates ζ. Β made of aluminum lead to a very short knife service life. Knife broth are very difficult to remove from the surface and lead to incorrect shutdowns and damage to the steel. Conductive additives made of graphite have insufficient conductivity at low concentrations; at higher concentrations, the material-specific properties of the base material are largely lost
fen.

Better results are achieved with a punching plate in which a contact body in the form of a metal fiber fleece is embedded. Such punching plates have become known from DE-PS 12 51461. To at the To achieve a sufficiently high conductivity on the die plate surface is a high volume fraction Metal fiber fleece or metal knitted fabric required. These metal thread structures must be in sufficient quantity placed in the casting mold in order to evenly fill the entire volume of the plate casting mold mechanical contact between the threads to ensure a sufficiently high To get conductivity of the metal thread structure. However, a high proportion of thread makes production more difficult homogeneous plates due to strong air inclusions during the casting process. In addition, through the high content of metal thread structures the specific properties of the base material z. B. polyamide strongly adversely affected. Another disadvantage is that by rearrangement of the metal threads with insulating acting thermoplastic melts interrupted the electrical contact points between the metal threads and thus can become conditionally inoperable, d. h., ever Depending on the size of the damage, entire surface parts of the punching plate become ineffective as contact punching plates.

After prolonged use of a punching plate with metal thread or knitted metal reinforcement, a Post-processing of the surface is carried out by planing the board, preferably on a thicknessing machine will. It is inevitable that the knife of the processing tool due to the high metal content wear out very quickly and at the same time entire sections of metal fiber due to the planing process cut through the surface.

Experience has shown that these metal fiber ends tend to come out of the softer base plate slightly, in the worst case several millimeters leak out, them form a large number of metal tips on the surface thus machined, which z. B. textile punched material Damage the string and lead to incorrect electrical contacts.

The invention is based on the object of creating a constancy plate which has the described Does not have a defect. This object is achieved with one designed according to the claims Contact body.

The drawings show exemplary embodiments for the contact body embedded in the punching plate shown, namely shows

Fi g. I a strip-shaped metal foil,

2 shows two metal foils bent in the shape of corrugated sheet metal and an intermediate foil.

F i g. 3 three metal foils shaped into tubes. In the embodiment according to FIG. 1 is in the off Polyamide-cast punching plate 1 of the contact body from a strip 2 bent in the shape of a snake formed, the tracks 3 are at a small distance next to each other and its surfaces perpendicular to Support surface 4 of the punching plate 1 are arranged. An end face of the strip 2 is not over one power source shown electrically connected to the drive mechanism for the punch knife, The Strip 2 has the perforation holes 5, which have the purpose that the material to be potted

is positively connected over the entire cross-section.

According to FIG. 2, the contact body is made of metal foil (7, T) bent like a corrugated sheet with a perforation *

tion holes, which are in two layers in the plate 1 is embedded in mirror image.

Another embodiment for the contact body results from the fact that several perforated metal foils which are formed into tubular structures 8 and close to one another in the plate 1 can be used are embedded.

For the production of the punched contact plates, the metal foils used as contact bodies are vertical hung in an upright casting mold and with the thermoplastic melt, in particular with

Polyamide, or encapsulated with a thermosetting resin compound. In terms of quantity, the proportion of metal foil represents represents a fraction of the previously necessary fleece-shaped metal deposits. The casting process is carried out does not affect the perpendicular arrangement of the foils to the direction of casting. In the case of a subsequent mechanical Processing of the plate surfaces, no pieces of metal thread can protrude from their surface. An electrically conductive, smooth die plate surface is created.

For this purpose 3 sheets of drawings

Claims (5)

Patent claims: 1. Contact punching plate made of plastic with an embedding made of a metallic material a contact body as a base for an electrically driven punch knife for punching out of flat objects made of leather, plastic and other punchable materials, characterized in that the contact body consists of one or more of the duro- or thermoplastic material of the plate is encapsulated, electrically conductive metal parts is formed 2. Contact punching plate according to claim 1, characterized in that the metal foil is in one piece as loop-shaped bent strip (2) is formed, the adjacent webs (3) with their surfaces are arranged perpendicular to the support surface (4) of the punching plate (1). 3. Contact punching plate according to claim 1, characterized in that the metal foil (7, T) is shaped like a corrugated sheet and is arranged in two mirror-inverted layers 4. Contact lancet according to claim I, characterized in that the metal foil in the form of Tubes (8) are formed which are arranged close together. 5. contact punching plate according to claim 1, characterized in that a plurality of metal foils as adjacent strip sections are arranged, which are electrically connected to one another and the surfaces of which are arranged perpendicular or parallel to the support surface of the plate.