JP5041877B2 - Dry friction material - Google Patents

Description

  The present invention relates to a dry friction material, for example, a dry friction material constituting a torque limiter used in an automobile or the like, and more particularly, to a dry friction material that does not generate rust with a metal friction counterpart material. Is.

  In recent years, systems that include dry friction materials such as clutch facings, dampers, torque limiters, etc. have tended to be smaller and lighter, and in systems that include dry friction materials, improve the wear resistance of dry friction materials. Is one of the effective means for reducing the size and weight of the system. In addition, if the size is the same, it can be mounted on a higher load system.

  As a manufacturing method of the clutch facing, as shown in Patent Document 1, a fiber bundle (glass roving) in which long fibers as a base material are bundled is impregnated with an impregnating liquid containing a thermosetting resin to form a resin-impregnated string. A resin impregnation step and a rubber adhering step for adhering the compounded rubber to the resin impregnated string, the medium of the impregnating liquid is water, and the thermosetting resin is an aqueous solution having a melamine compounding ratio of 30% to 80%. A method characterized by being a melamine-modified phenol resin is known. According to the technique of Patent Document 1, a material for a friction material that does not deteriorate the performance of a dry friction material (clutch facing, etc.) of a final product without using an organic solvent in a resin impregnation process or a rubber adhesion process is manufactured. be able to.

Moreover, as shown in Patent Document 2, as a dry friction material manufacturing method including clutch facing, a dry friction material mainly composed of a base material, a resin, and a rubber material contains a porous carbon material. The invention characterized by this is disclosed. Thus, by blending the porous carbon material with the dry friction material, it is said that the wear resistance is good even under conditions of high rotation and high temperature, and a high friction coefficient can be maintained.
JP 2000-037797 A Japanese Patent Application Laid-Open No. 2000-256652

  However, in both the technique described in Patent Document 1 and the technique described in Patent Document 2, since a steel plate is used as the friction counterpart material of the dry friction material, the steel plate is used under severe usage conditions such as high humidity. There is a problem that rusting occurs between the friction material and problems such as clutch fixation.

  Therefore, the present invention can be manufactured in the conventional process by maintaining the strength of the dry friction material while reducing the ratio of the area of the glass fiber to the friction surface of the dry friction material to a predetermined value or less, and the metal An object of the present invention is to provide a dry friction material capable of maintaining strength and friction characteristics while preventing rusting with a manufactured friction counterpart material.

The dry friction material according to the invention of claim 1 is a dry friction material containing glass fiber, a synthetic resin for impregnating glass fiber, and a compounded rubber, wherein the friction counterpart material is made of metal, and the glass fiber and the glass A lower layer in which the synthetic resin for fiber impregnation and the blended rubber are blended substantially uniformly and an upper layer made of only the blended rubber in which the area of the glass fiber occupying the friction surface is 0% are integrated.

  Here, “compound rubber” is a material constituting a dry friction material, such as rubber such as synthetic rubber and natural rubber, pigment such as carbon black, sulfur, vulcanization accelerator, resin dust, calcium carbonate, etc. A rubber-based mixture containing a filler. As the “synthetic rubber”, acrylonitrile-butadiene rubber (also referred to as NBR, nitrile rubber), styrene-butadiene rubber (SBR), or the like can be used alone or in combination.

Further , the dry friction material is a two-layer friction material formed by integrally molding a lower layer in which the glass fiber, the synthetic resin for impregnating glass fiber, and the compounded rubber are compounded substantially uniformly and an upper layer of only the compounded rubber. It is a material, The ratio of the thickness of the said upper layer with respect to the thickness of the said lower layer exists in the range of 20%-85%.

A dry friction material according to a second aspect of the present invention is the structure of the first aspect, wherein the system constituted by the dry friction material is a torque limiter.

The dry friction material according to the invention of claim 1 is a dry friction material containing glass fiber, a synthetic resin for impregnating glass fiber, and a compounded rubber, wherein the friction counterpart material is made of metal, and the glass fiber and the glass A lower layer in which the synthetic resin for fiber impregnation and the blended rubber were blended substantially uniformly, and an upper layer made of only the blended rubber in which the area of the glass fiber in the friction surface was 0% were integrated.

  Here, “compound rubber” is a material constituting a dry friction material, such as rubber such as synthetic rubber and natural rubber, pigment such as carbon black, sulfur, vulcanization accelerator, resin dust, calcium carbonate, etc. A rubber-based mixture containing a filler. As the “synthetic rubber”, acrylonitrile-butadiene rubber (also referred to as NBR, nitrile rubber), styrene-butadiene rubber (SBR), or the like can be used alone or in combination.

  The inventor has conducted extensive experimental research on the occurrence of rust under high humidity conditions in a dry friction material having a metal friction partner material such as steel, and as a result, on the friction surface with the friction partner material. It has been found that rusting does not occur when the proportion of the area occupied by the glass fiber is 40% or less, and the present invention has been completed based on this finding. That is, when the ratio of the area occupied by the glass fiber on the friction surface is 40% or less, it was found that rust does not occur even under high humidity conditions.

  Here, in the case of a normal one-layer type friction material formed by substantially uniformly molding glass fiber, a synthetic resin for impregnating glass fiber and compounded rubber as a dry friction material, a volume of a certain amount or more is required to maintain strength. Since it is necessary to contain glass fiber at a content rate, the ratio of the area occupied by glass fiber on the friction surface cannot be 0%.

  However, in the case of a two-layer type friction material formed by integrally molding a lower layer in which glass fiber, a synthetic resin for impregnating glass fiber and compounded rubber are blended substantially uniformly and an upper layer of only the compounded rubber, the lower layer is constant. By containing glass fibers having a value equal to or greater than the value, the ratio of the area occupied by the glass fibers on the friction surface can be reduced to 0% while maintaining the strength as a dry friction material.

  Thus, by maintaining the strength of the dry friction material while reducing the ratio of the area of the glass fiber to the friction surface of the dry friction material to a predetermined value or less, it can be manufactured in a conventional process and made of metal It becomes a dry-type friction material which can maintain intensity | strength and a friction characteristic, preventing rusting between these friction counterpart materials.

Furthermore, the dry friction material is a two-layer friction material formed by integrally molding a lower layer in which glass fiber, a synthetic resin for impregnating glass fiber, and a compounded rubber are compounded substantially uniformly and an upper layer of only the compounded rubber. The ratio of the upper layer thickness to the lower layer thickness is in the range of 20% to 85%, more preferably in the range of 25% to 60%.

  As a result of diligent experimental research, the inventor of the present invention has a two-layer dry type formed by integrally molding a lower layer in which glass fiber, a synthetic resin for impregnating glass fiber and a compounded rubber are blended substantially uniformly, and an upper layer of only the compounded rubber. In the friction material, when the ratio of the thickness of the upper layer to the thickness of the lower layer is in the range of 20% to 85%, it was found that the strength of the dry friction material is maintained and can withstand high-speed rotation. The present invention has been completed based on the above.

  That is, in the entire two-layer dry friction material, the friction surface is composed only of compounded rubber and the ratio of the area of the glass fiber to the friction surface is 0%. Therefore, even under severe usage conditions such as high humidity, the friction surface There is no concern about rusting with the mating material, but if the proportion of the upper layer consisting only of the compounded rubber is too large, the strength as a dry friction material will be reduced and it will not be able to withstand high-speed rotation and will be destroyed.

  Here, in the two-layer dry friction material, if the ratio of the upper layer thickness to the lower layer thickness is 85% or less, the strength as the dry friction material is maintained and can withstand high-speed rotation, and If the ratio of the thickness of the upper layer to the thickness of the lower layer is 20% or more, the upper layer will not be worn even after long-term use, and the glass fiber will not be exposed to the friction surface, so rust will occur. There is no fear of doing. Therefore, the ratio of the upper layer thickness to the lower layer thickness is preferably in the range of 20% to 85%.

  Furthermore, if the ratio of the thickness of the upper layer to the thickness of the lower layer is in the range of 25% to 60%, the strength as a dry friction material is improved, and the thickness of the friction surface (upper layer) that does not contain glass fiber is also increased. Since it becomes thicker, it is more preferable.

  Thus, by maintaining the strength of the dry friction material while reducing the ratio of the area of the glass fiber to the friction surface of the dry friction material to a predetermined value or less, it can be manufactured in a conventional process and made of metal It becomes a dry-type friction material which can maintain intensity | strength and a friction characteristic, preventing rusting between these friction counterpart materials.

In the dry friction material according to the invention of claim 2, the system constituted by the dry friction material is a torque limiter. In the dry friction material according to the first aspect of the present invention , it is possible to reliably prevent rusting with a metal friction partner material even under severe usage conditions such as high humidity. Therefore, it is particularly suitable as a dry friction material used for a torque limiter.

  Thus, by maintaining the strength of the dry friction material while reducing the ratio of the area of the glass fiber to the friction surface of the dry friction material to a predetermined value or less, it can be manufactured in a conventional process and made of metal It becomes a dry-type friction material which can maintain intensity | strength and a friction characteristic, preventing rusting between these friction counterpart materials.

  Next, the dry friction material according to the embodiment of the present invention will be described. In the second and subsequent embodiments, the same symbols and the same reference numerals as those in the first embodiment mean the same or corresponding functional parts as those in the first embodiment, and the same symbols and the same in the embodiments. The reference numeral is a functional part common to those embodiments, and therefore detailed description thereof is omitted here.

Embodiment 1
First, a dry friction material according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a schematic configuration of a torque limiter using a dry friction material according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing a manufacturing process of the dry friction material according to Embodiment 1 of the present invention. FIG. 3 is an explanatory diagram showing the dimensions of the specimen used for the performance evaluation of the dry friction material according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the dry friction material 3 according to the first embodiment is a ring-shaped molded body having an outer diameter of φ220 mm × an inner diameter of φ190 mm × a thickness of 2.4 mm, and has the same outer diameter and a slightly smaller inner diameter. Attached to both sides of the ring-shaped cored bar 4 is used. The torque limiter 1 according to the first embodiment includes a friction plate in which the dry friction material 3 is attached to both surfaces of a cored bar 4, and a friction counterpart material that is pressed by the friction plate and transmits a driving force torque from the engine. The steel plate pressure plate 2 and the rotation shaft 5 for transmitting the rotation of the friction plate to the AT are constituted.

  Next, a method for manufacturing the dry friction material 3 according to the first embodiment will be described with reference to FIG. First, in the resin impregnation step, a glass-impregnated string is formed by impregnating a glass fiber with an impregnation liquid containing a phenol resin (more specifically, a melamine-modified phenol resin) as a synthetic resin for glass fiber impregnation (step S10). Subsequently, in the rubber attaching process, the compounded rubber is attached to the resin-impregnated string (step S11), and in the winding process, the resin-impregnated string to which the compounded rubber is attached is wound up to a predetermined size (step S12).

  Here, as the “compound rubber”, a synthetic rubber, a mixture mainly composed of rubber containing pigments such as carbon black, sulfur, a vulcanization accelerator, and resin dust / calcium carbonate is used. As the rubber, acrylonitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR) are mixed and used.

  In the molding process, the wound product is pressed into the mold and heated and pressed (step S13). In the molding process, several times of degassing are performed at a surface pressure of 15 MPa and a temperature of 165 ° C. Heat and pressure mold for 2 minutes. The molded body is taken out from the mold, heat-treated at 240 ° C. for 10 hours (step S14), then allowed to cool to room temperature, and then both front and back surfaces are polished (step S15), and the first embodiment is applied. The dry friction material 3 is completed.

  In the first embodiment, the five types of dry friction materials of Examples 1 to 5 were manufactured by changing the volume content of the glass fiber within the range of 5 vol% to 18 vol%. For comparison, dry friction materials of Comparative Example 1 consisting only of compounded rubber containing no glass fiber and Comparative Example 2 having a glass fiber volume content of 22 vol% were also produced. The blending ratios of Examples 1 to 5, Comparative Example 1 and Comparative Example 2 are shown in the upper part of Table 1.

  The characteristics of the dry friction materials of Examples 1 to 5, Comparative Example 1 and Comparative Example 2 prepared according to the flow chart of FIG. Regarding the appearance ratio of the glass fiber to the friction material surface, that is, the ratio of the area occupied by the glass fiber on the friction surface of the dry friction material, the area ratio was calculated by measuring the size of the glass fiber portion. For rusting properties, a specimen immersed in water for a specified time is brought into close contact with the mating material (steel plate) at a prescribed pressure and held in a prescribed environment, and then the specimen and the mating material (steel plate) are rusted. The load was measured with a push-pull gauge.

  As shown in FIG. 3, the specimen for evaluation of rustability was parallel to the center line of the ring from a ring-shaped dry friction material 3 having an outer diameter of 220 mm, an inner diameter of 190 mm, and a thickness of 2.4 mm. In addition, a specimen TP having a width of 25 mm was cut out and used.

  In addition, with respect to the rotational fracture strength, using a specimen in which the dry friction material 3 is adhered to both surfaces of the cored bar 4, the rotational fracture strength is rotated at a predetermined holding temperature, a predetermined holding rotation speed, and a predetermined holding time at a high speed. The presence or absence of cracks was evaluated. These evaluation results are shown in the lower part of Table 1, and detailed evaluation conditions are shown in the margins of Table 1.

  As shown in the lower part of Table 1, the appearance ratio of the glass fiber to the friction material surface is that in the specimens of Examples 1 to 5 in which the volume content of the glass fiber is in the range of 5 vol% to 18 vol%. Is within the range of 10% to 40%. On the other hand, in the comparative example 1 which consists only of compounded rubber, the appearance ratio of the glass fiber on the friction material surface is naturally 0%, and the specimen of the comparative example 2 in which the volume content of the glass fiber is 22 vol%. Is 49%, exceeding 40%.

  As a result, the load with rust is an average value of 10 specimens, and in Examples 1 to 5 and Comparative Example 1, it is within a small value of 0 (zero) N to 49 N, whereas In Example 2, it was a large value of 194 N, and it was found that rusting was noticeably generated under the conditions of a temperature of 50 ° C., a humidity of 90% RH or more and a surface pressure of 1.3 MPa for 72 hours.

  In addition, with respect to the rotational fracture strength, in the test conditions of holding for 5 minutes at an atmospheric temperature of 130 ° C. and a rotational speed of 10000 rpm, in Examples 1 to 5 and Comparative Example 2, no fractures or cracks occurred on 10 specimens. On the other hand, in Comparative Example 1 consisting only of compounded rubber containing no glass fiber, all 10 specimens were broken. Thus, it was found that the rotational fracture strength was insufficient with the formulation containing no glass fiber.

  Therefore, from the results shown in the lower part of Table 1, sufficient rotational fracture strength can be obtained by setting the glass fiber volume content in the dry friction material 3 to 5 vol% or more, and the glass fiber volume content in the dry friction material 3 is obtained. It has been found that by controlling the rate to 18 vol% or less, the appearance ratio of glass fibers to the friction material surface can be suppressed to 40% or less, and rusting under severe conditions can be prevented.

  Thus, in the dry friction material 3 which concerns on this Embodiment 1, by making the volume content rate of glass fiber into the range of 5 vol%-18 vol%, the glass fiber which occupies for the friction surface of a dry friction material The strength of the dry friction material can be maintained while reducing the area ratio to a predetermined value or less, and it can be manufactured in the conventional process, and it is strong while preventing rusting with the metal friction counterpart. And frictional properties can be maintained.

Embodiment 2
Next, a dry friction material according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view showing the structure of the dry friction material according to Embodiment 2 of the present invention.

  As shown in FIG. 4, the dry friction material 10 according to the second embodiment includes a lower layer 10B in which glass fiber, a melamine-modified phenol resin as a synthetic resin for impregnating glass fiber, and a compounded rubber are blended substantially uniformly. This is a two-layer type friction material formed by integrally molding the upper layer 10A only of compounded rubber.

  The dry friction material 10 according to the second embodiment can be manufactured by the same manufacturing process as the dry friction material 3 according to the first embodiment. That is, in the flowchart of FIG. 2, in the molding step of Step S <b> 13, only the compounded rubber is further pressed after the wound product is pressed into the mold, and the heat and pressure molding is performed. Other steps can be performed according to the flowchart of FIG.

In the dry friction material 10 manufactured in this way, the ratio of the thickness α (mm) of the upper layer 10A to the thickness β (mm) of the lower layer 10B, that is, (α / β) × 100 (%) is variously changed, When the rotational fracture test was conducted in the same manner as the dry friction material 3 according to the first embodiment, almost no fracture or crack occurred when it was in the range of (α / β) × 100 = 20% to 85%. However, it was found that when the value of (α / β) × 100 exceeds 85, destruction / cracking occurs.
Therefore, the ratio of the thickness α of the upper layer 10A to the thickness β of the lower layer 10B in the dry friction material 10 is preferably in the range of 20% to 85%.

  In the case of (α / β) × 100 = 25% to 60%, no destruction or cracking occurred. Therefore, the ratio of the thickness α of the upper layer 10A to the thickness β of the lower layer 10B in the dry friction material 10 is more preferably in the range of 25% to 60%.

  Furthermore, when the rusting property evaluation was performed in the same manner as the dry friction material 3 according to the first embodiment, in the dry friction material 10 according to the second embodiment, the upper layer 10A is composed only of compounded rubber, and the friction surface. Since the area of the glass fiber occupying was zero, the load with rust was zero.

  Thus, in the dry friction material 10 according to the second embodiment, the ratio of the thickness α of the upper layer 10A to the thickness β of the lower layer 10B is set in the range of 20% to 85%, thereby providing dry friction. The strength of the dry friction material can be maintained while reducing the area of the glass fiber on the friction surface of the material to zero, and it can be manufactured in the conventional process and prevents rusting with the metal friction material. However, strength and friction characteristics can be maintained.

  In each of the above embodiments, the case where a melamine-modified phenol resin is used as a synthetic resin for impregnating glass fibers has been described, but other modified phenol resins, other thermosetting resins such as epoxy resins, and the like are used. You can also. In particular, melamine-modified phenolic resin is easily available and is excellent in heat resistance, and is therefore preferable as a synthetic resin for impregnating glass fibers as a material for dry friction materials.

  In carrying out the present invention, the composition, components, blending amount, material, size, manufacturing method, and the like of other parts of the dry friction material are not limited to the above embodiments.

  In addition, since the numerical value quoted in each said embodiment does not show a critical value but shows a suitable value suitable for implementation, even if the numerical value is slightly changed, its implementation is not denied. Absent.

FIG. 1 is a cross-sectional view showing a schematic configuration of a torque limiter using a dry friction material according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing a manufacturing process of the dry friction material according to Embodiment 1 of the present invention. FIG. 3 is an explanatory diagram showing the dimensions of the specimen used for the performance evaluation of the dry friction material according to Embodiment 1 of the present invention. FIG. 4 is a schematic cross-sectional view showing the structure of the dry friction material according to Embodiment 2 of the present invention.

1 Torque limiter 2 Friction material 3,10 Dry friction material 4 Core metal 10A Upper layer 10B Lower layer

Claims (2)

A dry friction material containing glass fiber, a synthetic resin for impregnating glass fiber, and a compounded rubber, wherein the friction partner is made of metal,
The glass fiber, the glass fiber-impregnated synthetic resin and the compounded rubber are mixed in a substantially lower layer, and the upper layer made of only the compounded rubber in which the area of the glass fiber in the friction surface is 0%, and The dry friction material, wherein the ratio of the thickness of the upper layer to the thickness of the lower layer is in the range of 20% to 85%. The dry friction material according to claim 1, wherein the system constituted by the dry friction material is a torque limiter.

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