DE1042352B - Lubrication process when cold pressing a punch into the face of pressed metal parts - Google Patents

Description

The aim of the invention is to facilitate the pressing in of a stamp, e.g. B. to form a blind hole, in a pressed part, in particular in an uninterrupted sequence of steps, on automatic presses, such as Cold impact pressing, is produced and in which the face into which the punch is pressed with no firmly adhering lubricant or a layer that absorbs a lubricant can.

The friction that occurs during such cold forming causes a considerable additional amount Exertion of force and seizure phenomena, especially when it comes to pressed steel parts.

Usually, the starting material is given a lubricious coating of non-ferrous metal or Lime or a coating of zinc or manganese phosphate !, which is the actual lubricant, which is applied later, should soak up. Since this wire, however, before starting processing in individual Sections is dismantled, the shear surfaces of the pressed part have no lubricious or lubricant-absorbent Coating. However, the deformation should take place precisely into these shear surfaces. Will during the work process on the shear surface of the pressed part or on the penetrating tool If lubricant is sprayed, it cannot switch off the metallic friction between the tool and the pressed part, because an effective lubricating film cannot develop due to the high surface pressure.

According to a known method, the pressed part is cold-formed on two cold heading presses. Between the pre- and final deformation the blank is provided with a lubricious coating again, so that the shear surface into which the blind hole is pressed on the second machine, also with a lubricious coating is provided. This creates metallic friction at the critical points and thus preventing seizure between the tool and the pressed part. The pressed parts can not do this a single automatic press. Rather, you need the second machine be fed with a special device with magazine. This is the manufacture more complicated, more time-consuming and correspondingly more expensive.

When punching blocks, it is also known to apply a pane of glass to the end face. When it hits, the punch separates a portion from this that penetrates into the block and - in a viscous condition - lubricates the punch. This procedure is only suitable for Hot processing and a non-continuous mode of operation.

That cover layers made of soft metal act as lubricants

Cold pressing lubrication method

of a stamp in the face

of pressed parts made of metal

Applicant:

Bauer & Schaurte,

Screw and nut factory,

Neuss / Rhine

Dipl.-Ing. Gerhard Junker, Neuss / Rhine,
has been named as the inventor

means are suitable for cold forming, has already been mentioned.

Soft metal cover layers are also used in foil form. A proposal is known to cover the end face of high-strength metals such as nickel with a copper foil during hot extrusion or less malleable alloys of aluminum with foils made from easily malleable materials such as aluminum, Aluminum-zinc alloys, among other things, to be used as lubricants.

It is also known that a loose pad of malleable metal, such as copper, can be cold along with a blank made of other metal, such as aluminum, can be pressed up on a punch in such a way that the The edition together with the base metal, covering this, increases.

The invention is based on the knowledge that just metal foils in certain applications lead to a surprisingly simple solution to the lubrication problem outlined above.

The lubrication method according to the invention is that over the end face of the pressing part as Lubricant a film strip made of softer metal is brought from which the stamp is used Pressing on the end face each punched out a proportion corresponding to its circumference and then with presses in.

Of course, it must be ensured that the circumference of the stamp first, at least evenly with its entire surface, comes to impact. That is easily achievable, especially when the Front face has been pre-pressed in a trough shape before deep pressing, as is customary.

809 661/82

Claims (2)

An advantageous device for carrying out this method is characterized by castors mounted on the press ram between an unwinding drum and a take-up drum, as well as a switching mechanism through which the film strip can be advanced gradually along the face of the ram during the ram return stroke. An example of application of the invention is shown in the drawing and explained below. Fig. 1 to 3 show the tool of a cold heading press together with the workpiece and metal foil in different working positions, Fig. 4 shows a device for feeding the metal foil, Fig. 5 shows the section of a metal foil. In Figs. 1 to 3, the ram is denoted by W. The pressed part P is inserted into the die H. The band-shaped metal foil F, which is used for lubrication during the pressing in of the blind hole, is inserted between the pressed part P and the tool W. In Fig. 1 the punch is shown at the beginning of the working stroke. In Fig. 2 he has punched a plate FP from the metal foil F and pressed it against the pressed part P. From Fig. 2 it can be seen that the punch is designed and the pressed part is preformed so that the punch sits on the periphery of the pressed part. In Fig. 3 the end of the working stroke is shown; the punch W has penetrated deeply into the pressing part P and the stamped-out foil plate FP enclosed between the punch and the pressing part flowed upwards under the pressure against the movement of the punch on the wall of the blind hole. This significantly reduces the friction between the punch and the pressed part and prevents seizure. The method can be carried out with a device indicated in FIG. In this device, a film strip F with edge perforations O is wound on the drum T1. The film strip runs from this supply drum T1 over deflection rollers A and U from the end face of the machine bear B and the stamp W attached to it over to a second drum T2. The guide roller A is provided as a drive roller with teeth which enter the perforation O of the belt F. The drive roller A is coupled to a gear, which has the effect that the film strip F is advanced by a work width during the return stroke of the machine. The tape guiding direction is arranged in such a way that the film tape F is guided past the end face of the tool W approximately 1 to 2 mm. The punch W is surrounded by a spring-loaded scraper ring S, which scrapes the tape F from the tool on the backward stroke of the tool. The foil tape used in this device is shown in a section in Fig. 3. The perforations O are of course worked into the device before the tape is used. The advance of the foil strip F during the return stroke of the machine is, as is customary with the continuous punching of holes in strips, so great that the holes resulting from the punching out of the platelets FP do not destroy the connection of the strip. The advance of the tape can of course be adjusted in the usual way. Patent answer ρ κrche: 1. Smearing process when cold pressing a punch into the face of pressed parts Metal, in particular steel, characterized in that over the end face of the pressed part as Lubricant a film strip made of softer metal is brought from which the When penetrating the end face, the punch punches out a proportion corresponding to its circumference and then press in. 2. Device for feeding the film strip for the lubricant method according to claim 1, characterized by the press ram (B) between an unwinding _{drum (T 1} ) and a winding drum (T ₂ ) mounted castors (U, A) and a switching mechanism through which the film strip (F) is gradually displaceable along the face of the punch (W ) during the bear return stroke. Considered publications:
German patent specifications No. 279 534, 703 161,
735 243, 936 324; British Patent No. 689 051;
French Patent No. 988 870;
Swiss patent specification No. 169 574. 1 sheet of drawings © 809 661/82 10.58