KR20030045117A - Method for producing ceramic brake disks, with an insert in the green body before the pyrolysis - Google Patents

Abstract

The present invention relates to a method for producing a ceramic brake from a green compact consisting of a sheet molding compound (SMC) with reinforcing fibers, including pyrolysis and melt penetration. It is an object of the present invention to produce a single member green compact comprising a very complex internal cavity after pyrolysis. In order to achieve this, the present invention allows the green compact 1 to be operated once in a tool 5a, 5b to which pressure and temperature are applied, from a sandwich consisting of SMC 2, thermoplastic insert 4 and SMC 2; And a step 6, wherein the insert comprises a hole 6 which is arranged in such a way that the top and bottom SMC layers 2 are at least in place connected to each other in place, filling the green compact in a fully expanded state. .

Description

METHOD FOR PRODUCING CERAMIC BRAKE DISKS, WITH AN INSERT IN THE GREEN BODY BEFORE THE PYROLYSIS}

This method is known from PCT / EP00 / 00253. In this way, the green compact is molded from a sheet molding compound (SMC) having a matrix of synthetic resin and reinforcing fibers of carbon in a tool under pressure and temperature. Subsequently, the green compact is pyrolyzed for the purpose of producing a porous molded article. As a further process step, the melt penetration of the porous shaped article is carried out with a melt, suitably a silicone melt, for the purpose of making the shaped article into reactive bond fibers.

In this way, the green compact consists of two separate parts, which are connected as a result of the melt penetration to form one part.

From DE 44 38 455 C1 a method for producing ceramic brake discs is known, in which the green compacts are made in one piece and the individual cores are inserted into the green compacts before pyrolysis for the purpose of creating a defined cavity.

The present invention relates to a method for manufacturing a ceramic brake disc.

1 shows an open tool (press) for producing a green compact with an SMC inserted and an insert before a pressing operation.

Figure 2 shows the same tool according to figure 1 after a pressing operation;

3A and 3B show the insert in two parts.

4A and 4B show a green compact before thermal electrolysis and before processing.

5A and 5B show a green compact before and after thermal electrolysis.

6A and 6B show a green compact after thermal electrolysis.

7A and 7C are cross-sectional views taken along line B1-B1 in FIG. 3A.

7B and 7D are cross sectional views taken along the line B2-B2 in FIG. 6A.

It is an object of the present invention to provide a method for producing a ceramic brake disc in which one-piece green compacts exhibiting a very complex internal cavity after pyrolysis can be economically produced by simple means. As a result, the ceramic brake disc generated after the infiltration of the melt has a low weight structure.

According to the invention, the object of the invention is achieved by the features of claim 1.

The main feature of the present invention is that SMCs having a matrix of phenolic resins are used and comprise reinforcing fibers of carbon. The length of these carbon fibers is between 6 mm and infinity. From this particular SMC, the green compact is produced in a tool (press) by applying pressure and temperature.

To create a very complex cavity in the green compact, a sandwich of SMC, thermoplastic insert and SMC is placed in the tool and processed in one work step. By "sandwich" is meant herein a laminate having a lower layer of SMC, an upper layer of SMC and an insert arranged therebetween.

According to the invention, the thermoplastic insert is filled with the green compact in a fully expanded state and at the same time shaped by holes in such a way that the upper and lower SMC layers are connected to each other at least in place.

In the course of the next pyrolysis of the green compact, the inserts collide on their own, creating a one-piece part with a very complex cavity.

The melt penetration of this porous molded product is then carried out with a melt, suitably a silicone melt, for the purpose of producing the molded product into reactive bond fibers. This molded product constitutes a real ceramic brake disc.

In a preferred embodiment, in the course of the manufacture of the green compact, the insert is completely clouded around the SMC and enclosed by the SMC. In this case, the insert must then be exposed on the side face of the green compact by machining before pyrolysis. As a result of this exposure, the gases released during the pyrolysis process can escape.

Preferably, additional holes for the insert can be introduced into the pyrolytic electrolytic green compact. These holes may have a round or other shape.

For the purpose of improving the cooling effect, the surface of the insert can be enlarged by protruding cooling fins on the insert. As a result, the enlarged inner surface of the cavity is made in the green compact after pyrolysis.

In a preferred method, the inserts are made of high temperature resistant thermoplastics or polyamides, such as, for example, polypropylene, polycarbonate.

Further features of the present invention can be seen from the drawings described below.

1 shows an open tool for producing a green compact, which acts as a press and has an upper part 5a and a lower part 5b. The sandwich consisting of the SMC 2 and the insert 3 is placed in the lower part 5b around the female mold 7 and the insert 4 is inserted between the two layers of the SMC 2. This insert 4 is described further below.

The processing operation takes place by pressing the upper portion 5a with respect to the lower portion 5b while applying pressure and temperature.

2 shows the tools 5a and 5b after the pressing operation. The SMC 2 is liquefied under the application of pressure and temperature to completely surround the insert 4. After the curing process, the green compact should be finished and just pulled out of the tools 5a, 5b.

3a and 3b show the insert 4 in two parts. The insert 4 is preferably made from polyamide, ie composed of thermoplastic material. It is shown in such a way that the holes 6 are simultaneously shaped in a wide open state, with the lower and upper SMC layers (see FIGS. 1 and 2) connected at least in place.

In the embodiment shown here, the insert 4 comprises holes 6 which are bores uniformly distributed on two circles arranged centrifugally with respect to each other about the center point of the insert. In this case the inner circle comprises twelve holes 6 and the other circle comprises twenty four holes 6. 3B is a cross-sectional view taken along the line A-A in FIG. 3A.

4a and 4b show the finished green compact 1 before pyrolysis, ie after the pressing operation, as shown in FIGS. 1 and 2. 4B is a cross-sectional view taken along the line A-A in FIG. 4A. It can be seen that the insert 4 is completely surrounded by the SMC 2.

At this stage, holes (not shown) for the insert can be introduced through the SMC 2.

However, in a preferred manner, the green compact 1 is processed at the side faces 9a, 9b before pyrolysis, in particular in such a way that the insert is exposed on the side faces 9a, 9b of the green compact. This has the advantage that undesirable high pressures cannot occur at all within the green compact 1 during the pyrolysis process.

5A and 5B show the green compact 1 after this processing. The state of the side faces 9a and 9b before processing is shown by the dotted line. Importantly in connection with this, the insert 4 is exposed after processing. FIG. 5B is a cross-sectional view taken along the line A-A in FIG. 5A.

6a and 6b show the green compact after pyrolysis, ie after the porous molded article 3 has just been produced. FIG. 6B is a cross-sectional view taken along the line A-A in FIG. 6A. The insert is completely pyrolyzed and then disappears. In the place where the insert is placed in the green compact, a cavity or vent 8 now occurs. The hole in the insert is the point of connection between the top and bottom layers of the SMC.

By a final working step, the porous molded article 3 is subjected to melt penetration, preferably with a melt, preferably a silicone melt, for the purpose of making the molded article into reaction-bonded fibers. The molded product then consists of the actual brake discs. The appearance is the same as that of FIGS. 6A and 6B.

For the purpose of enlarging the surface area of the vent tube 8 and for improving the cooling effect, in an advantageous manner, the insert exhibits a shape in the area of the hole which results in an enlarged surface area in the finished brake disc.

7A and 7C both show cross-sectional views taken along line B1-B1 in FIG. 3A and show the shape of the holes in the insert 4. FIG. 7A shows the dog bone shape and FIG. 7C shows the shape with the cooling fins 10 protruding vertically.

7B and 7D both show a cross-sectional view taken along the line B2-B2 of FIG. 6A, showing the particular shape of the insert 4, ie the state after pyrolysis, with the vent 8 being formed as a result of pyrolysis. . The vent tube 8 is arranged in the porous molded article 3 at the place where the insert 4 is prepositioned.

Claims (6)

A method for producing a green compact (1) consisting of an SMC (2) having a matrix made of a phenol resin and a reinforcing fiber made of carbon, wherein the length of the carbon fiber is between 6 mm and infinite, and the porous molded product (3) is The green compact manufacturing method which thermally decomposes the green compact 1 for the purpose of manufacture, and subsequently melt-penetrates the porous molded product into a melt, suitably a silicon melt, for the purpose of producing the molded product into reactive bond fibers, Manufacturing the green compact 1 from a sandwich consisting of SMC 2, thermoplastic insert 4 and SMC 2 in one working step in tools 5a and 5b under pressure and temperature Include, The insert is shaped by a hole (6) in such a way that it fills the green compact in a fully expanded state and at the same time the upper and lower SMC layers (2) are connected to each other at least in place. The method of claim 1, wherein in the manufacturing process of the green compact (1), the insert (4) is completely blurred around the SMC (2) and enclosed by the SMC (2). The method for manufacturing a green compact according to claim 2, wherein the insert (4) is exposed to the side face by machining before pyrolysis of the green compact (1). The process according to any one of the preceding claims, wherein a further hole for the insert is introduced into the green compact (1) prior to pyrolysis. The method according to any one of claims 1 to 4, wherein the projecting cooling fins are arranged on the insert. The method of claim 1, wherein the insert is made of a high temperature resistant thermoplastic or polyamide, such as, for example, polypropylene, polycarbonate.