WO2019121534A1

WO2019121534A1 - Method and device for producing a friction lining for a vehicle brake

Info

Publication number: WO2019121534A1
Application number: PCT/EP2018/085248
Authority: WO
Inventors: Adrian PIEKARSKI
Original assignee: Lucas Automotive Gmbh
Priority date: 2017-12-22
Filing date: 2018-12-17
Publication date: 2019-06-27
Also published as: DE102017011960A1

Abstract

The invention relates to a method for producing a friction lining for a vehicle brake, comprising the steps: providing a forming tool (12), which defines the form of a friction lining to be produced, providing a material mixture for producing a friction lining, wherein the material mixture has ferromagnetic particles, filling the material mixture into the forming tool (12), carrying out a compression process, wherein a predetermined pressure is applied to the material mixture in the forming tool (12), and controlling the temperature of the material mixture in the forming tool (12) during the compression process by means of an inductive energy source (14) arranged on the forming tool (12).

Description

Method and device for producing a friction lining

for a vehicle brake

The present invention relates to a method for producing a friction lining for a vehicle brake. An apparatus for producing a friction lining for a vehicle brake is also an object of the present invention.

Various methods for producing a friction lining for a vehicle brake are known from the prior art. The document DE 2 238 558 discloses a device for producing friction linings. The friction linings can have different compositions. The properties of some plastics contained in the compositions may deteriorate when exposed to high temperatures. For example, synthetic synthetic fibers, saturated resins and cellulose are very heat sensitive. For this reason, the friction linings are to be exposed to high temperatures for a short time when gluing the friction linings to a support body, usually a support plate made of metal.

It is known to heat a metallic support body by means of an induction source quickly to heat the adhesive on the support body for connection to the friction linings. Document DE 2 818 371 C3 discloses a device in which the carrier body or lining carrier is heated by means of an induction source. As a result, the adhesive is heated to the lining carrier and can produce the desired adhesive connection with the friction lining.

The document US Pat. No. 2,520,978 discloses a method in which the lining carrier or the brake shoe is heated for the thermal activation of an adhesive in order to establish a connection between the friction linings and the brake shoe by means of the adhesive.

Further, document US 2 642 919 discloses a method in which the lining carrier is heated by means of an induction source to heat an adhesive so that a connection between the lining carrier and the friction lining can be made via the adhesive.

Finally, it is known from the prior art to thermally post-treat friction linings after their production. For example, the document US 4 081 307 the thermal aftertreatment of the friction linings after their production by means of an infrared oven to remove moisture from the friction linings.

It is an object of the present invention to simplify the production of friction linings, in particular for vehicle brakes.

This object is achieved by a method according to claim 1 or according to claim 9 and by a device for producing a friction lining with the features of claim 11.

Further advantageous embodiments are specified in the dependent claims.

The method according to the invention for producing a friction lining for a vehicle brake comprises the following steps:

Providing a mold that specifies the shape of a friction lining to be produced,

Providing a material mixture for producing a friction lining, the material mixture having ferromagnetic particles,

Filling the material mixture into the mold,

Performing a pressing operation, wherein the material mixture is applied in the mold with a predetermined pressure, and

Controlling the temperature of the material mixture in the mold during the pressing operation by means of an inductive energy source arranged on the mold.

The inductive energy source generates an alternating magnetic field, which induces eddy currents in the ferromagnetic particles, which result in heating of these particles. In this way, the temperature of the material mixture in the mold can be controlled. The state of aggregation of the material mixture can also be controlled via the temperature of the material mixture in the mold. Through the inductive energy source, the temperature of the material mixture in the mold during the pressing process can be controlled so that the friction linings have their predetermined properties directly after the pressing process, without a thermal treatment is required. It can be saved with the inventive method compared to the prior art thus a process step. Because thermal aftertreatment is no longer necessary in the method according to the invention, in the case of ßen procedures the cycle time for each friction lining to be produced are reduced. As a result, the total time required for the production of the friction linings can be significantly reduced. In addition, since inductive energy sources are extremely effective, energy and equipment costs can be saved.

Further, when using an inductive power source, heating elements need no longer be disposed within the mold. This can also reduce the time and cost of producing friction linings.

The inductive energy source generates, as already mentioned, an alternating magnetic field ^¬ which acts on the ferromagnetic particles in the material mixture. The power of the inductive energy source is transmitted by means of the alternating magnetic field to the ferromagnetic particles in the material mixture and converted there into heat due to induced eddy currents and magnetization losses. By means of the heat generated by the inductive energy source and the ferromagnetic particles in the material mixture, the material mixture pressurized by a press can melt in the mold and be pressed into the desired shape. Here, the press pressure on the mold or the material mixture contained in the mold step increase ^¬ wise.

The temperature of the material mixture contained in the mold can be controlled via the current intensity of the inductive energy source and the current supplied ^¬ A duration of action of the alternating magnetic field. The temperature of the material mixture and the state of aggregation of the mixture of materials determined by the temperature can be controlled by means of the current supplied to the inductive energy source such that the finished friction lining has predetermined properties. The inductive energy source can be traversed by a high-frequency current. The frequency of the current may be in a range of 25 to 50 kHz.

The inductive energy source may comprise an induction coil. The Induktionsspu ^¬ le may be disposed in the vicinity of the mold. The induction coil is preferably such arranged on the pressing tool, that the Materialmi ^¬ research is detected in the mold from the produced by the induction coil magneti ^¬ rule alternating field.

As ferromagnetic material, a material can be used which has a high efficiency in the conversion of electromagnetic energy into heat. has energy. For example, the ferromagnetic particles may be made of a material having a high electrical resistance. The ferromagnetic particles preferably have a predefined density. Ferromagnetic particles of materials with a predefined density can advantageously assist the process, as the ferromagnetic particles concentrate the alternating magnetic field generated by the inductive energy source. The magnetic field can generate eddy currents in a thin outer layer of the ferromagnetic particles. Due to the comparatively large ohmic resistance of the ferromagnetic particles and the generated eddy currents, most of the electrical power of the inductive energy source is converted into heat output. Another part of the energy introduced into the ferromagnetic particles is converted into thermal energy by the magnetization losses (hysteresis). As the ferromagnetic material, a stainless iron alloy may preferably be used.

During the pressing process, a connection between the material mixture in the mold and a brake pad support plate of a brake pad to be produced can be generated. The mold can accommodate the brake pad support plate. In the mold, a receptacle for the brake pad carrier plate may be formed. Deviating from the prior art is a

Connection of the brake pad support plate with the material for the friction lining directly and directly in the mold during the pressing process. As a result, an additional method step can be saved compared with the prior art. The brake pad support plate may be made of a ferromagnetic material. The brake pad support plate may be provided with an adhesive on its side facing the friction lining material for connection to the friction lining material. The adhesive may be thermally activated. The adhesive may preferably be thermally activated by the heated friction lining material. The press may exert a predetermined pressure on the brake pad support plate and the material mixture during the pressing operation to densify the material and establish communication between the material mixture and the brake pad support plate.

The temperature of the material mixture in the mold can be controlled by the inductive energy source such that the material mixture can cure in the mold. By means of the inductive energy source, the temperature and thus also the physical state of the material mixture in the mold in dependence on the current intensity of the inductive energy source supplied power can be adjusted individually. The curing can be controlled with the inductive energy source so that the friction lining after the manufacturing process has predetermined properties. The curing step can the

Complete the manufacturing process of the friction lining.

The temperature of the material mixture can be detected. For detecting the temperature sensors may be provided. The temperature sensors may be in direct contact with the material mixture. The material mixture for the production of the friction lining may, in addition to the already mentioned ferromagnetic particles and filler particles and / or binder particles such as a binder resin. The material mixture may have a predetermined proportion of ferromagnetic particles. The proportion of ferromagnetic particles can be, for example, between 0.5 and 5% of the friction lining weight. Preferably, the proportion of ferromagnetic particles is 2% of the friction lining weight. The binder resin may preferably be heat-fusible. While the press compacts the material mixture with the ferromagnetic particles, the filler particles and / or the binder particles, the induction coil generates an alternating magnetic field. This alternating field causes the desired increase in the temperature of the ferromagnetic particles. The binder resin contained in the material mixture absorbs the heat from the heating ferromagnetic particles and liquefies. The molten binder resin combines the particles of different materials contained in the material mixture.

To achieve with the inductive energy source quickly to high temperatures Kgs ^¬ NEN, the current supply may be regulated to the inductive power supply so that the process time is kept as low as possible. In addition, a short process time and appropriate temperature control can prevent the ferromagnetic particles from heating up to the Curie temperature, beyond which they lose their ferromagnetic properties. The Curie temperature of play, in ^¬ iron is 768 ° C.

The provided material mixture with the ferromagnetic particles is filled into the mold. About the press or a press shop the Materialmi ^¬ shear is applied in the mold with pressure. By the pressure of the press, the material mixture is compressed in the mold to achieve a predetermined density or consistency of the material mixture. The press can gradually increase the mixture. At the same time, the ferromagnetic particles in the material mixture are heated by the inductive energy source and heat is thus introduced into the material mixture contained in the mold. As a result of the heat, the binder resin present in the material mixture is melted. The molten binder resin intimately bonds with the remaining particles of the material mixture. The temperature is controlled by the inductive energy source so that the binder resin can cure. In other words, the cooling of the binder resin can also be controlled via the inductive energy source. The outer shape produced by this method as well as the density of the friction lining are retained after the curing of the binder resin.

The interaction of the induction source with the ferromagnetic particles in the material mixture, the heat can be distributed homogeneously in the material mixture. This homogeneous heat distribution increases the viscosity of the friction lining during reflow, and it is also possible to produce complex shapes of the friction linings in the molding tool. For example, chamfers to be attached to the edge of the friction lining can be produced directly by means of the molding tool or the negative mold of the friction lining contained in the molding tool. As a result, the friction lining no longer has to be mechanically reworked in order to provide it with predetermined contours.

The present invention further relates to a method for producing a friction lining for a vehicle brake, comprising the steps:

Providing a mold that specifies the shape of a friction lining to be produced,

Providing a material mixture for producing a friction lining,

Filling the material mixture into the mold,

Controlling the temperature of the material mixture in the mold during the pressing operation by means arranged on the mold means for generating electromagnetic waves.

By means of the electromagnetic waves generated by the device for generating electromagnetic waves, the temperature of the material mixture can be controlled so that the material mixture can first liquefy and subsequently harden. The electromagnetic waves cause the molecules of the material mixture to move, resulting in the material mix friction or in the particles of the material mixture friction, which increases the temperature of the material mixture. The state of aggregation of the material mixture can also be controlled via the temperature of the material mixture in the mold. With the device for generating electromagnetic waves, the temperature of the material mixture in the mold during the pressing process can be controlled such that the friction linings immediately after the pressing process have their predetermined properties, without a thermal treatment is required. The device for generating electromagnetic waves can generate electromagnetic waves in the microwave range. For example, the electromagnetic wave generating device may generate in a frequency range of 915 MHz to 2.45 GHz. The material mixture may contain metal particles. Preferably, these metal particles are of a metal that can not reflect electromagnetic waves. These metal particles may for example consist of iron. The iron particles may heat up due to the action of the electromagnetic waves, whereby the temperature of the material mixture may also be increased. The material mixture for the production of the friction lining may also comprise filler particles and / or binder particles such as a binder resin in addition to the metal particles. The binder resin may preferably be heat-fusible. The binder resin contained in the material mixture can melt due to the friction generated in the particles by the electromagnetic waves. In addition, the binder resin can absorb the heat from the heating metal particles. The molten binder resin combines the particles of different materials contained in the material mixture.

By means of the press, the material mixture is pressurized in the mold. At the same time, the material mixture is heated by the device for generating electromagnetic waves. As a result of the heat, the binder resin present in the material mixture is melted, so that the individual particles of the material mixture can bond to one another. The temperature is controlled by the means for generating electromagnetic waves so that the binder resin can cure. Also, the cooling of the binder resin can be controlled by the means for generating electromagnetic waves. Obtain the outer shape produced by this method as well as the density of the friction lining lead ^¬ ben after curing of the binder resin. The device according to the invention for producing a friction lining for a vehicle brake comprises a molding tool. In addition, the device according to the invention comprises an inductive energy source and / or a device for generating electromagnetic waves. The mold specifies the shape of the friction lining to be produced and absorbs the material mixture for producing the friction lining. The mold is designed such that it can be pressurized by a press. The inductive energy source and / or the means for generating electromagnetic waves is / are arranged on the mold for the transmission of energy. The temperature of the material mixture within the molding tool can be controlled by means of a control device assigned to the inductive energy source and / or the device for generating electromagnetic waves.

Since the device according to the invention for producing a friction lining comprises an inductive energy source and / or a device for generating electromagnetic waves, the temperature and also the state of aggregation of the material mixture in the mold can be controlled with the device according to the invention such that thermal treatment of the friction linings can be dispensed with after the pressing process or after production.

The inductive energy source is preferably arranged so that the magnetic alternating field generated by the inductive energy source can act on the material mixture in the mold. The inductive energy source may surround the mold and / or be disposed on one side of the mold. Preferably, the inductive energy source is above or below the

Forming tool arranged. For example, the inductive energy source may extend at the bottom of the mold.

The inductive energy source may comprise an induction coil, preferably made of copper. The inductive energy source may further include a circuit connected to the induction coil. The induction coil can surround the mold. The molding tool can be arranged inside the induction coil. The inductive energy source may additionally be equipped with a cooling device. The cooling device can be, for example, a water cooling device.

The mold may consist of an austenitic-ferritic steel. Furthermore, the molding tool can be produced from another, non-ferromagnetic metal. be that does not heat up under the influence of induction. As examples, aluminum or aluminum oxide may be mentioned here. The tool may also be made of a material which heats up by the influence of the inductive energy source. Such a tool may be advantageous if the surface of the friction lining to be subjected by the heating tool an additional surface treatment. Temperatures for such surface treatment may be temperatures prior to reaching the eutectic phase boundary. Further, the mold may be made of a material that does not reflect electromagnetic waves. Preferably, the mold is made of a non-electromagnetic wave electromagnetic wave metal.

The mold may be configured to receive a brake pad carrier plate. Thereby, a connection between the material for the friction lining and the brake lining carrier plate can be produced during the pressing process and thus in a single process step.

The mold may define a fillable space into which the Materialmi ^¬ research can be introduced. The mold may have a negative mold of the friction lining, which specifies the shape of the friction lining to be produced. The negative mold can be open on one side. In a one-sided open negative mold can penetrate a with a press-coupled pressing member and exert pressure on the contained in the Ne ^¬ gativform material mixture. The one-sided open negative mold can be designed such that the pressing element can close the negative mold and can be displaced relative to the negative mold. The pressing element can be moved into the negative mold in order to pressurize the material mixture contained in the negative mold. The pressing member may be formed in the form of a punch.

The device may include temperature sensors for detecting the temperature of the material mixture. The temperature sensors may be attached to the mold. The temperature sensors may be arranged in the negative mold, which determines the shape of the friction lining, and / or on a pressing element. The pressing member may be coupled to a press for applying pressure to the Materialmi ^¬ research in the mold.

The device can have a control device, which in particular controls the power supply to the inductive energy source and / or the action time of the alternating magnetic field on the molding tool. The controller may also be the Control press or press shop. Furthermore, the control device can be connected to the temperature sensors.

The device for generating electromagnetic waves may be arranged on one side of the molding tool. Alternatively, the means for generating electromagnetic waves may be integrated into the mold. The means for generating electromagnetic waves may be a magnetron.

Two embodiments of a device for producing a friction lining will be described in more detail below with reference to the attached schematic figures. Show it:

Fig. 1 is a view of a device according to a first

Embodiment;

Fig. 2 is a view of a device according to a second

Embodiment;

3 shows a view of the pressing element and the negative mold with the friction lining produced therein;

4 shows views of the friction lining produced with the device; and

Fig. 5 is a view of a device according to a third

Embodiment.

Fig. 1 shows a view of a device 10 for producing a Reibbeiags according to a first embodiment. The device 10 comprises a molding tool 12 and an inductive power source 14.

The mold 12 has two mold halves 16 and 18. In the lower half 18 in Fig. 1, a recess 20 is formed, in which a material mixture 22 can be introduced. The recess 20 has a negative mold, which specifies the shape of the brake lining to be produced. The upper half 16 in FIG. 1 has a recess 24 which can receive the brake lining carrier plate 26 of the brake lining to be produced. The mold 12 is coupled to a press. The molding tool 12 can be pressurized via the press in order to compact the material mixture 22 contained in the recess 20. The inductive energy source 14 has an induction coil 28, which is connected to a circuit 30. The circuit 30 comprises a switch S, a capacitor U ₀ , a current source A, a resistor R and a coil L, which are connected in series.

According to the first exemplary embodiment, the induction coil 28 surrounds the molding tool 12 and thus the material mixture 22 contained in the molding tool 12 and the brake lining carrier plate 26. The molding tool 12 is thus arranged inside the induction coil 28. The material mixture 22 contains ferromagnetic particles that can be vibrated by the induction coil 28. Heat is generated by the vibration of the ferromagnetic particles, which causes the binder resin contained in the material mixture 22 to melt. At the same time pressure is exerted by the press on the mold 12, whereby the material is compressed. The molten binder resin bonds the particles of material mixture in the mold together and can also connect to the brake pad support plate 26.

Fig. 2 shows a view of a device 10 according to a second embodiment. According to FIG. 2, the molding tool 12 is open on one side. The molding tool 12 has a recess 20 in which the material mixture 22 is received. The recess 20 has a negative mold, which specifies the shape of the brake lining to be produced. The recess 20 is closed by a pressing element 32. The pressing element 32 is coupled to a press 34 or a pressing plant. The press 34 can gradually increase the pressure on the material mixture 22 in the mold 12 via the pressing element 32. The pressing element 32 is displaceable relative to the forming tool 12 in order to be able to compact the material mixture 22 contained in the recess 20. The pressing member 32 is stamp-shaped and displaceable into the recess 20 of the mold 12. On the pressing member 32 34 pressure for compacting the material 22 in the recess 20 is applied by a press.

The inductive energy source 14 is also formed in the second embodiment in the form of an induction coil 28 which is connected to a circuit 30. However, unlike the first embodiment, the induction coil 28 does not surround the molding tool 12, but is disposed below the molding tool 12. The induction coil 28 thus extends along the underside of the molding tool 12. The radius of the induction coil 28 may be larger than the base surface the recess 20 may be in the mold 12 to ensure that the alternating magnetic field of the inductive energy source 14 can act on the entire material mixture contained in the recess 20 22.

3 shows a view of the molding tool 12 and the pressing member 32 according to the second embodiment. FIG. 3 shows the friction lining 36 produced. The mold 12 is provided with temperature sensors 38. The pressing element 34 also has temperature sensors 40 with which the temperature in the material mixture or in the molten material can be determined.

The temperature sensors 38 and 40 may be connected to a controller 42. The control device 42 can also control the press 34 or the pressing plant and the inductive energy source 14.

4 shows views of the produced friction lining 36 in a schematic representation. In Fig. 4, the measuring points or measuring positions 44 are entered, in which the temperature sensors 38 and 40 of the mold 12 and the

Pressing element 34 determine the temperature in the material mixture or in the produced friction lining 36.

In one embodiment, not shown, the inductive power source is configured to surround the mold and further extend along the bottom of the mold.

5 shows a view of a device 10 according to a third exemplary embodiment. The device 10 includes the forming tool 12 and means 48 for generating electromagnetic waves. The molding tool 12 has a recess 20 in which the material mixture 22 is received. The recess 20 has a negative mold, which specifies the shape of the brake lining to be produced. The recess 20 is closed by a pressing element 32. The pressing element 32 is coupled to a press 34 or a pressing tool.

The means 48 for generating electromagnetic waves is arranged on the mold-forming ^¬ 12th The device 48 is located below the molding tool, with the device 48 extending along the underside of the molding tool 12. The device 48 for generating electromagnetic waves may be a Mag ^¬ netron that generates electromagnetic waves in the microwave range. The electromagnetic waves generated by the device 48 can act on the material mixture 22 in the recess 20, so that the temperature of the material mi- tion 22 by means of the device 48 and the electromagnetic waves generated by it can be controlled. The mold 12 is preferably made of a material that does not reflect electromagnetic waves. The device 48 is connected to the circuit 30. The circuit 30 comprises the switch S, the capacitor U ₀ , the current source A, the resistor R and the coil L, which are connected in series.

8415413

Claims

claims

1. A method for producing a friction lining for a vehicle brake, comprising the steps of:

Providing a mold (12), which specifies the shape of a friction lining to be produced,

Providing a material mixture (22) for producing a friction lining, wherein the material mixture (22) comprises ferromagnetic particles,

Filling the material mixture (22) into the mold (12),

Performing a pressing operation, wherein the material mixture (22) is applied in the mold (12) with a predetermined pressure, and

Controlling the temperature of the material mixture (22) in the mold (12) during the pressing operation by means of an inductive energy source (14) arranged on the mold (12).

2. The method according to claim 1,

wherein the inductive energy source (14) generates an alternating magnetic field which acts on the ferromagnetic particles in the material mixture (22).

3. The method according to claim 1 or 2,

wherein the temperature of the material mixture (22) received in the mold (12) is controlled by the current intensity of the current supplied to the inductive power source (14).

4. The method according to any one of claims 1 to 3,

wherein the inductive energy source (14) is traversed by a high-frequency current.

5. The method according to any one of claims 1 to 4,

wherein the ferromagnetic particles are made of a material having a high efficiency in the conversion of electromagnetic energy into heat energy.

6. The method according to any one of claims 1 to 5,

wherein a connection between the Materialmi ^¬ research (22) in the mold (12) and a support plate (46) is obtained of a product to the brake pad during the pressing operation.

7. The method according to any one of claims 1 to 6,

wherein the temperature of the material mixture (22) received in the mold (12) is controlled by means of the inductive energy source (14) such that the material mixture (22) cures in the mold (12).

8. The method according to any one of claims 1 to 7,

wherein the material mixture (20) comprises filler particles and / or heat-meltable binder particles.

9. A method for producing a friction lining for a vehicle brake, comprising the steps of:

Providing a material mixture (22) for producing a friction lining, filling the material mixture (22) in the mold (12),

Controlling the temperature of the material mixture (22) in the mold (12) during the pressing operation by means of an electromagnetic wave generating device (48) arranged on the mold (12).

10. The method according to claim 9,

wherein the means (48) for generating electromagnetic waves generates electromagnetic waves in the microwave range.

11. Device (10) for producing a friction lining for a vehicle brake, comprising:

a molding tool (12) having a recess (20) defining the shape of the friction lining (36) to be produced and for receiving a material mixture (22) for producing the friction lining, the molding tool (12) being adapted to be fed by a press To be pressurized

an inductive energy source (14) and / or means (48) for generating electromagnetic waves, which is / are arranged on the molding tool (12), and

a control device for controlling the temperature of the material mixture (22) within the mold (12) by means of the inductive energy source (14) and / or by means (48) for generating electromagnetic waves.

12. Device according to claim 11,

wherein the inductive energy source (14) surrounds the mold (12) and / or is disposed on one side of the mold (12).

13. Device according to claim 11 or 12,

wherein the inductive energy source (14) comprises an induction coil (28).

14. Device according to one of claims 11 to 13,

wherein the mold (12) is made of an austenitic-ferritic steel or a non-ferromagnetic material or a non-electromagnetic wave electromagnetic metal.

15. Device according to one of claims 11 to 14,

wherein the mold (12) is adapted to receive a brake pad support plate (26).

16. Device according to one of claims 11 to 15,

wherein the mold (12) has a negative mold, which dictates the shape of the friction lining (36) to be produced.

17. Device according to one of claims 11 to 16,

the apparatus comprising temperature sensors (40, 42) measuring the temperature of the mixture of materials in the mold (12) and connected to the control means.

18. Device according to one of claims 11, 14 to 17,

wherein the means (48) for generating electromagnetic waves on one side of the mold (12) is arranged or integrated into the mold (12).

19. Device according to one of claims 11, 14 to 18,

wherein the means (48) for generating electromagnetic waves is a Mag ^¬ netron.