DE102017011960A1 - Method and device for producing a friction lining for a vehicle brake - Google Patents

Abstract

The invention relates to a method for producing a friction lining for a vehicle brake comprising the following steps: providing a molding tool 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 in 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 power source arranged on the mold.

Description

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 publication 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. The publication DE 2 818 371 C3 discloses for this purpose a device in which the support 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 publication US Pat. No. 2,520,978 discloses a method in which the pad backing or shoe is heated to thermally activate an adhesive to bond the friction pads to the brake shoe by means of the adhesive.

Further, the document discloses US 2,642,919 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 discloses 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 and by a device for producing a friction lining with the features of claim 9.

Further advantageous embodiments are specified in the dependent claims.

• - Bereitstellen eines Formwerkzeugs, das die Form eines herzustellenden Reibbelags vorgibt,
• - Bereitstellen einer Materialmischung zum Herstellen eines Reibbelags, wobei die Materialmischung ferromagnetische Partikel aufweist,
• - Einfüllen der Materialmischung in das Formwerkzeug,
• - Ausführen eines Pressvorgangs, wobei die Materialmischung in dem Formwerkzeug mit einem vorbestimmten Druck beaufschlagt wird, und
• - Steuern der Temperatur der Materialmischung in dem Formwerkzeug während des Pressvorgangs mittels einer an dem Formwerkzeug angeordneten induktiven Energiequelle.

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

• Providing a mold which predetermines 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 in 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, the cycle time for each friction lining to be produced can be reduced in the method according to the invention. 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. Also This can reduce the time and cost of producing friction linings.

As already mentioned, the inductive energy source generates 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. In this case, the press can gradually increase the pressure on the mold or the material mixture contained in the mold.

The temperature of the material mixture contained in the mold can be controlled by the current intensity of the current supplied to the inductive energy source and the duration of the 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 induction coil can be arranged in the vicinity of the molding tool. The induction coil is preferably arranged on the pressing tool such that the material mixture in the molding tool is detected by the alternating magnetic field generated by the induction coil.

As the ferromagnetic material, a material having a high conversion efficiency of electromagnetic energy into heat energy can be used. 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 alternating 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, a connection of the brake lining carrier plate with the material for the friction lining is 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 current 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 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 may for example be 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.

In order to quickly reach high temperatures with the inductive energy source, the power supply to the inductive energy source can be regulated 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, for example, iron is 768 ° Celsius.

The provided material mixture with the ferromagnetic particles is filled into the mold. About the press or a press shop, the material mixture is pressurized 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 further densify the material mixture step by step. 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. Due to 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.

By 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 inventive device for producing a friction lining for a vehicle brake comprises a mold and an inductive energy source. 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 acted upon by a press with pressure. The inductive energy source is arranged on the mold for inductive transmission of energy and the temperature of the material mixture within the mold is controllable by means of a control device associated with the inductive energy source.

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

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 arranged above or below the mold. 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 mold 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 mold may be made of another, non-ferromagnetic metal 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.

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 can define a fillable space into which the material mixture 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 negative mold open on one side, a pressing element coupled to a press can penetrate and exert pressure on the material mixture contained in the negative mold. 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 material mixture in the mold.

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

• 1 eine Ansicht einer Vorrichtung gemäß einem ersten Ausführungsbeispiel;
• 2 eine Ansicht einer Vorrichtung gemäß einem zweiten Ausführungsbeispiel;
• 3 eine Ansicht des Presselements und der Negativform mit dem darin hergestellten Reibbelag; und
• 4 Ansichten des mit der Vorrichtung hergestellten Reibbelags.

Two embodiments of an apparatus for producing a friction lining are described in more detail below with reference to the accompanying schematic figures. Show it:

• 1 a view of a device according to a first embodiment;
• 2 a view of a device according to a second embodiment;
• 3 a view of the pressing member and the negative mold with the friction lining produced therein; and
• 4 Views of the friction lining produced with the device.

1 shows a view of a device 10 for producing a friction lining according to a first embodiment. The device 10 includes a mold 12 and an inductive energy source 14 ,

The mold 12 has two mold halves 16 and 18 , In the in 1 lower half 18 is a recess 20 formed into which a material mixture 22 can be introduced. The recess 20 has a negative mold, which dictates the shape of the brake pad to be produced. In the 1 upper half 16 has a recess 24 holding the brake pad backing plate 26 can record the brake pad to be produced. The mold 12 is coupled with a press or a press shop. The mold 12 can be pressurized via the press to those in the recess 20 contained material mixture 22 to condense.

The inductive energy source 14 has an induction coil 28 on that with a circuit 30 connected is. The circuit 30 includes a switch S , a capacitor U _O , a power source A , a resistance R and a coil L which are connected in series.

According to the first embodiment, the induction coil surrounds 28 the mold 12 and with that in the mold 12 contained material mixture 22 and the brake pad support plate 26 , The mold 12 is thus inside the induction coil 28 arranged. The material mixture 22 Contains ferromagnetic particles passing through the induction coil 28 can be vibrated. The vibration of the ferromagnetic particles generates heat, which is in the the material mixture 22 melt down contained binder resin. At the same time, pressure is applied to the mold by the press 12 exercised, whereby the material is compacted. The molten binder resin bonds the particles of material mixture in the mold together and also can connect to the brake pad support plate 26 produce.

2 shows a view of a device 10 according to a second embodiment. According to 2 is the mold 12 open on one side. The mold 12 has a recess 20 in which the material mixture 22 is included. The recess 20 has a negative mold, which dictates the shape of the brake pad to be produced. The recess 20 is from a pressing element 32 locked. The pressing element 32 is with a press 34 or a press shop coupled. The press 34 can over the pressing element 32 the pressure on the material mixture 22 in the mold 12 gradually increase. The pressing element 32 is relative to the mold 12 displaced to those in the recess 20 contained material mixture 22 to be able to condense. The pressing element 32 is stamp-shaped and in the recess 20 of the mold 12 into relocatable. On the pressing element 32 is from a press 34 Pressure to compress the material 22 in the recess 20 applied.

The inductive energy source 14 is also in the second embodiment in the form of an induction coil 28 trained with a circuit 30 connected is. Unlike the first embodiment, the induction coil surrounds 28 the mold 12 not, but is below the mold 12 arranged. The induction coil 28 thus extends along the bottom of the mold 12 , The radius of the induction coil 28 can be larger than the footprint of the recess 20 in the mold 12 to be sure that the magnetic alternating field of the inductive energy source 14 on the whole in the recess 20 contained material mixture 22 can act.

3 shows a view of the mold 12 and the pressing element 32 according to the second embodiment. In 3 is the manufactured friction lining 36 recognizable. The mold 12 is with temperature sensors 38 Provided. Also the pressing element 34 has temperature sensors 40 on, with which the temperature in the material mixture or in the molten material can be determined.

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

4 shows views of the manufactured friction lining 36 in a schematic representation. In 4 are the measuring points or measuring positions 44 entered, where the temperature sensors 38 and 40 of the mold 12 and the pressing element 34 the temperature in the material mixture or in the produced friction lining 36 determine.

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

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2238558 [0002]
• DE 2818371 C3 [0003]
• US 2520978 [0004]
• US 2642919 [0005]
• US 4081307 [0006]

Claims (15)

Method for producing a friction lining for a vehicle brake, with the steps: Providing a molding tool (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) in 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). 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). Method according to Claim 1 or 2 in that the temperature of the material mixture (22) accommodated in the mold (12) is controlled by means of the current intensity of the current supplied to the inductive energy source (14). Method according to one of Claims 1 to 3 , wherein the inductive energy source (14) is traversed by a high-frequency current. Method according to 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. Method according to one of Claims 1 to 5 wherein during the pressing operation, a connection between the material mixture (22) in the mold (12) and a support plate (46) is obtained of a brake pad to be produced. Method according to one of Claims 1 to 6 in that the temperature of the material mixture (22) accommodated 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). Method according to one of Claims 1 to 7 wherein the material mixture (20) comprises filler particles and / or heat-meltable binder particles. 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 power source (14) disposed on the inductive transmission forming 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). Device after Claim 9 wherein the inductive energy source (14) surrounds the mold (12) and / or is disposed on one side of the mold (12). Device after Claim 9 or 10 wherein the inductive energy source (14) comprises an induction coil (28). Device according to one of Claims 9 to 11 wherein the mold (12) is made of an austenitic-ferritic steel or a non-ferromagnetic material. Device according to one of Claims 9 to 12 wherein the mold (12) is adapted to receive a brake pad support plate (26). Device according to one of Claims 9 to 13 , wherein the mold (12) has a negative mold, which dictates the shape of the friction lining (36) to be produced. Device according to one of Claims 9 to 14 wherein the device comprises temperature sensors (40, 42) which measure the temperature of the material mixture in the mold (12) and are connected to the control device.

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