JP2007263203A - Wet type friction material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet type friction material having reliably improved friction property by precisely forming grooves as oil grooves in the surface of a base material for the friction material similarly to the case of forming oil grooves with pressing work while reducing pressing steps. <P>SOLUTION: In a process of manufacturing the base material for the friction material where segment pieces 3 as part of the wet type friction material 1 are cut out, a step of forming paper making grooves in the surfaces with pressing or cutting work while making paper is first performed, whereby a groove depth can be precisely formed because a paper making body has no elasticity. The wet type friction material 1 has total eighty oil grooves consisting of twenty segment grooves 5 formed in spaces among twenty segment pieces 3 and three paper making grooves each in the surfaces of the twenty segment pieces 3. In this way, deep segment grooves 5 and shallow paper making grooves 4 are mixed to obtain improved friction property which a conventional segment wet type friction material cannot have. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a high pressure on the opposite surface in a state immersed in oil, such as a wet clutch, a brake friction material, a lock-up friction material, etc. in an automatic transmission (hereinafter also abbreviated as “AT”) of an automobile or the like. The present invention relates to a wet friction material that obtains torque by applying a frictional material, and can obtain excellent friction characteristics equivalent to or better than when oil grooves are formed with a press while reducing the pressing process, and a method for manufacturing the same. .

  In recent years, there has been a demand for a reduction in drag torque and a high degree of smooth shifting feeling that aim to reduce fuel consumption of ATs. To solve these problems, automatic transmission fluid (hereinafter referred to as “ATF”) is required. The oil groove formed in the wet friction material is becoming more important.

  As a wet friction material, a paper body obtained by making a base fiber such as pulp or aramid fiber and a filler such as a friction additive or extender is impregnated with a resin binder made of a thermosetting resin. A ring-shaped friction material obtained by punching a friction material substrate formed by heat curing into a ring shape and bonding it to a flat ring metal core, and a shape from the friction material substrate along the R of the ring metal core A segment friction material obtained by punching a plurality of segment pieces and bonding these segment pieces to a flat ring metal core at intervals is used in a ratio of approximately half.

  In the ring-shaped friction material, before or after the friction material base material is punched into a ring shape, an oil groove is formed by providing a required number of grooves in the friction material base material by pressing (embossing) in the pressing process. . In the segment friction material, the interval between the segment pieces plays a role as an oil groove as it is. However, these oil grooves alone cannot satisfy the higher friction characteristics required for wet friction materials.

Therefore, in the invention described in Patent Document 1, in addition to the first oil groove formed by the interval between the segment pieces in the segment friction material, the second oil groove is formed on the surface of each segment piece by pressing (embossing). By forming it, the so-called μ-V positive gradient property can be maintained while suppressing an excessive increase in the clutch initial engagement friction coefficient.
JP 2004-211781 A

  However, in the invention disclosed in Patent Document 1 described above, each of the steps shown in FIG. 6 is required as the friction material base material manufacturing process among the wet friction material manufacturing processes. FIG. 6 is a flowchart showing a part of the manufacturing process of the wet friction material in the prior art.

  That is, as shown in FIG. 6, first, a paper making step (step S11) for obtaining a paper body is performed, and then the obtained paper body is impregnated with a resin binder made of a thermosetting resin (step S11). Friction that becomes the surface of each segment piece in the pressing (embossing) step (step S14) after performing the thermoforming step (step S13) of performing the step S12) and molding the impregnated thermosetting resin with a thermal effect A groove to be a second oil groove is formed on the surface of the material substrate.

  Accordingly, in order to manufacture the friction material base material that has been completed up to step S13 in the past, the press process in step S14 has to be increased, resulting in an increase in manufacturing cost and an increase in manufacturing time. Further, since the impregnated thermosetting resin was thermoset (step S13) and pressed (pressing) (step S14), the viscoelasticity of the friction material base material is large and the repulsive force is strong. For this reason, there is a problem that even if pressing is performed for a predetermined groove depth, the friction material base material is returned, and since this is not constant, the accuracy of the groove depth is lowered and the predetermined friction characteristic cannot be obtained. It was.

  Therefore, in the present invention, the oil groove is formed on the surface of the friction material base with high accuracy as in the case where the oil groove is formed by pressing while reducing the pressing process, thereby reliably ensuring excellent friction characteristics. It is an object of the present invention to provide a wet friction material that can be obtained and a method for producing the same.

  The wet friction material according to the invention of claim 1 is a wet friction material formed by adhering a ring-shaped friction material substrate or a segment piece cut out from a friction material substrate to all or both sides of a flat ring metal core. In the paper body state before impregnating the resin of the friction material base material, by forming a plurality of oil grooves of a predetermined shape having a predetermined depth and width on the friction material base material, the ring shape One or two or more oil grooves of a predetermined shape having a necessary depth and width are provided on the surface of the friction material base or the segment piece.

  The wet friction material according to a second aspect of the present invention is the wet friction material according to the first aspect, wherein 20 to 40 segment pieces are used per one circumferential surface of the flat plate ring-shaped cored bar. 1 to 4 oil grooves having a predetermined shape are provided.

  According to a third aspect of the present invention, there is provided a wet friction material manufacturing method in which a ring-shaped friction material substrate or a segment piece cut out from a friction material substrate is bonded to all or both sides of a flat ring metal core. A method of manufacturing a friction material, the step of forming a plurality of oil grooves having a predetermined depth and width while making or after papermaking the friction material substrate, and the friction material in the papermaking body state A step of impregnating a base material with a thermosetting resin, a step of heating the friction material base material impregnated with the thermosetting resin to cure the thermosetting resin to complete the friction material base material, A step of cutting out the ring-shaped friction material substrate or the segment piece from a friction material substrate, and a step of adhering the ring-shaped friction material substrate or the segment piece to all or both sides of the flat ring metal core And Is shall.

  The wet friction material according to the invention of claim 1 is a wet friction material formed by adhering a ring-shaped friction material substrate or a segment piece cut out from a friction material substrate to all or both sides of a flat ring metal core. In the paper body state before impregnating the resin of the friction material base material, a ring-shaped friction material base is formed by forming a plurality of oil grooves having a predetermined depth and width on the friction material base material. The surface of the material or segment piece is provided with one or more oil grooves of a predetermined shape having a necessary depth and width.

  That is, in the wet friction material according to the present invention, a plurality of oil grooves of a predetermined shape having a predetermined depth and width are formed on a friction material base material in a paper-making body state without viscoelasticity before impregnation with resin. Thus, since the repulsive force against the press or the like is extremely small, a plurality of oil grooves can be formed with high accuracy.

  Here, as a method of forming a plurality of oil grooves, pressing, cutting, or other methods may be used. In addition, “in the paper body state before impregnating the resin of the friction material base material, a plurality of oil grooves of a predetermined shape having a predetermined depth and width are formed in the friction material base material” means that paper making is completed. This means that a plurality of oil grooves may be formed later, or a plurality of oil grooves may be formed simultaneously with papermaking.

  This increases the accuracy of the groove depth and the like compared to conventional groove formation by pressing the friction material base material impregnated with a conventional resin, and the pressing process can be omitted. And shortening the time. Thus, a ring-shaped wet friction material or a segment wet friction material is manufactured by punching out the friction material base material on which a plurality of oil grooves are formed and bonding the friction material base material to a flat ring metal core.

  In this way, the oil groove is formed on the surface of the friction material base with higher accuracy as in the case where the oil groove is formed by pressing while reducing the pressing process, thereby ensuring excellent friction characteristics. The wet friction material can be obtained.

  In the wet friction material according to the invention of claim 2, 20 or more and 40 or less segment pieces are used per one circumferential surface of the flat plate ring-shaped metal core, and the oil groove having a predetermined shape provided on the surface of the segment piece is 1 or more and 4 or less.

  Thereby, in addition to the effect of claim 1, by setting the number of segment pieces to 20 or more and 40 or less per one circumferential surface of the flat ring metal core, the oil grooves provided between the segment pieces The number is 20 or more and 40 or less, which is the range of the number of oil grooves suitable for having excellent friction characteristics.

  In addition, when the number of segment pieces is less than 20, there is a problem that the width of the segment piece becomes large and the height of both end portions of the segment piece becomes small, and when the number of segment pieces exceeds 40, the segment piece However, by reducing the number of segment pieces to 20 or more and 40 or less per one circumferential surface of a flat plate ring-shaped cored bar, these problems are difficult to handle. Can be solved.

  Furthermore, by setting the number of oil grooves of a predetermined shape provided on the surface of the segment pieces to 1 or more and 4 or less, it is possible to maintain a balance with the number of oil grooves provided between the segment pieces, and to achieve excellent friction The characteristics can be obtained with certainty.

  In this way, the oil groove is formed on the surface of the friction material base with higher accuracy as in the case where the oil groove is formed by pressing while reducing the pressing process, thereby ensuring excellent friction characteristics. The wet friction material can be obtained.

  According to a third aspect of the present invention, there is provided a wet friction material manufacturing method in which a ring-shaped friction material substrate or a segment piece cut out from a friction material substrate is bonded to all or both sides of a flat ring metal core. A method of manufacturing a friction material, the step of forming a plurality of oil grooves having a predetermined depth and width while making or after papermaking the friction material substrate, and a friction material substrate in a papermaking body state A step of impregnating the thermosetting resin into the base material, a step of heating the friction material base material impregnated with the thermosetting resin to cure the thermosetting resin to complete the friction material base material, and a ring from the friction material base material. A step of cutting out the friction material substrate or the segment piece, and a step of bonding the ring friction material substrate or the segment piece to both or one side of the entire circumference of the flat ring metal core.

  That is, in the method for producing a wet friction material according to the present invention, a plurality of oil grooves of a predetermined shape having a predetermined depth and width are formed on a friction material substrate in a paper-making body state without viscoelasticity before impregnation with a resin. By forming, since the repulsive force with respect to a press etc. is very small, a some oil groove can be formed with sufficient precision. Here, as a method of forming a plurality of oil grooves, pressing, cutting, or other methods may be used.

  In this way, the friction material base material in a paper body state in which a plurality of oil grooves are formed is impregnated with a thermosetting resin, and subsequently heated to cure the thermosetting resin, thereby completing the friction material base material. A ring-shaped wet friction material or a segment wet friction material is manufactured by cutting out a ring-shaped friction material substrate or a segment piece from this friction material substrate and bonding it to both sides or one side of a flat ring-shaped cored bar. The

  Thus, in the method for producing a wet friction material according to the present invention, the accuracy of the groove depth and the like is increased as compared with the conventional groove formation by pressing the friction material base material after impregnating the resin. Since the pressing step can be omitted, the manufacturing process can be reduced in cost and time.

  In this way, the oil groove is formed on the surface of the friction material base with higher accuracy as in the case where the oil groove is formed by pressing while reducing the pressing process, thereby ensuring excellent friction characteristics. It becomes the manufacturing method of the wet friction material which can obtain the wet friction material which has this.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.

  FIG. 1 is a flowchart showing a part of a manufacturing process of a wet friction material according to an embodiment of the present invention. FIG. 2A is a partially enlarged plan view showing a part of the wet friction material according to the embodiment of the present invention in an enlarged manner, and FIG. 2B is a partial sectional view showing a section AA in FIG.

  FIG. 3A is a graph showing drag torque characteristics of a wet friction material (example) according to an embodiment of the present invention when the oil amount is 100 ml / min, compared with the conventional example, and FIG. 3B is an oil amount of 1000 ml. It is a graph which shows the drag torque in the case of / min compared with a prior art example. FIG. 4 is a graph showing the friction coefficient characteristics of the wet friction material (example) according to the embodiment of the present invention when the oil temperatures are 40 ° C., 80 ° C., and 120 ° C., as compared with the conventional example.

  FIG. 5A is an enlarged partial plan view showing a part of the wet friction material according to the first modification of the embodiment of the present invention, and FIG. 5B is a second modification of the embodiment of the present invention. The partial expanded plan view which expands and shows a part of wet friction material concerning, (c) is the partial enlarged plan view which expands and shows a part of wet friction material concerning the 3rd modification of embodiment of this invention. , (D) is a partially enlarged plan view showing a part of a wet friction material according to a fourth modification of the embodiment of the present invention, and (e) is a fifth modification of the embodiment of the present invention. It is a partial enlarged plan view which expands and shows a part of this wet friction material.

  The wet friction material according to the present embodiment is a segment wet friction material formed by adhering 20 segment pieces cut out from a friction material base material to both circumferential surfaces of a flat ring metal core. First, the manufacturing process of the friction material base material in the wet friction material concerning this Embodiment is demonstrated with reference to FIG.

  As shown in FIG. 1, in the manufacturing process of the friction material base material in the present embodiment, first, a step of forming grooves (hereinafter referred to as “papermaking grooves”) on the surface by pressing or cutting while papermaking is performed. (Step S1). Here, since the paper body has no elasticity, the groove depth and the like can be formed with high accuracy. Subsequently, a thermosetting resin is impregnated into the paper body having a paper groove formed on the surface (step S2). Then, the friction material substrate is completed by heating and molding the thermosetting resin while curing (step S3).

  As can be seen by comparing the manufacturing process of the friction material base material in the present embodiment shown in FIG. 1 with the above-described conventional manufacturing process of the friction material base material shown in FIG. Since the process can be omitted, the manufacturing process of the wet friction material can be reduced in cost and time.

  Wet friction according to the present embodiment is obtained by cutting out (punching) segment pieces from the friction material base material manufactured in this way and bonding 20 segment pieces to both sides of the flat ring-shaped cored bar. The material is manufactured.

  The segment wet friction material according to this embodiment manufactured in this manner will be described with reference to FIG.

  As shown in FIG. 2 (a), the wet friction material 1 according to the present embodiment includes a segment piece 3 in which three papermaking grooves 4 are formed on a plate ring-shaped cored bar 2 on an oily surface. Twenty pieces are bonded at predetermined intervals to be grooves. Accordingly, the wet friction material 1 has 20 oil grooves (hereinafter referred to as “segment grooves”) 5 each including a space between the 20 segment pieces 3 and 3 on the surface of the 20 segment pieces 3. The paper making grooves 4 are 3 × 20 = 60, and there are a total of 80 oil grooves.

  As shown in the cross-sectional view of FIG. 2B, among these oil grooves, the segment groove 5 is a deep groove reaching the surface of the cored bar 2, and the papermaking groove 4 is a shallow groove formed on the surface of the segment piece 3. It is a groove. Thus, by mixing the deep segment groove 5 and the shallow papermaking groove 4, excellent frictional characteristics that cannot be obtained by the conventional segment wet friction material can be obtained as described below.

  The wet friction material 1 according to the present embodiment (Example) was tested for friction characteristics as compared with a conventional segment wet friction material. As a conventional segment wet friction material, it is manufactured by Comparative Example 1 having only 20 segment grooves formed by adhering 20 normal segment pieces to both surfaces of the cored bar 2 and the manufacturing process shown in FIG. Comparative Example 2 having a total of 80 oil grooves of 20 segment grooves obtained by adhering 20 pieces of segment pieces having 3 press grooves on the surface to both surfaces of the core 2 and 60 press grooves was used. .

  First, a test was conducted on drag torque. As test conditions, the LVFA was used as a tester, the segment wet friction material had an outer diameter of 130.4 mm and an inner diameter of 107.5 mm, and the lubricating oil used was ATF. The amount of lubricating oil was 100 ml / min and 1000 ml / min. Two conditions were used, the oil temperature was 40 ° C., the frictional rotation number was changed from 500 rpm to 3500 rpm every 500 rpm, and the number of disks was set in triplicate. The groove width of the segment groove 5 is 2 mm. The results are shown in FIG.

  As shown in FIG. 3A, when the amount of lubricating oil is 100 ml / min, the drag torque is higher in both the example and the comparative example 2 than in the comparative example 1 in which the oil groove is only 20 segment grooves. Although reduced, it can be seen that the example is superior in drag torque reduction characteristics to the comparative example 2. Further, as shown in FIG. 3B, when the amount of lubricating oil is 1000 ml / min, both the example and the comparative example 2 exhibit substantially the same drag torque reduction characteristics as compared with the comparative example 1. Yes. Table 1 shows the results of calculating the drag torque reduction rate of the example and the comparative example 2 when compared with the comparative example 1.

  As shown in Table 1, the segment wet friction material 1 according to the example in which the papermaking groove 4 is formed has the drag torque reduction effect substantially equivalent to the segment wet friction material according to the comparative example 2 in which the conventional press groove is formed. I found out that

  Next, a μ-PT performance evaluation test was performed. As test conditions, after 50 cycles under the axial center standard load evaluation conditions, the friction rotation speed is 3600 rpm, the contact pressure is 0.196 MPa, 0.392 MPa, 0.588 MPa, 0.785 Mpa, the lubricating oil is ATF, and the lubricating oil amount is 600 ml. / Min, and the oil temperature was 40 ° C, 80 ° C, and 120 ° C. The results are shown in FIG.

  As shown in FIG. 4, in any of the oil temperatures of 40 ° C., 80 ° C., and 120 ° C., compared to Comparative Example 1, both Example and Comparative Example 2 have substantially the same initial friction coefficient μi reduction effect. Is shown. Table 2 shows the results of calculating the reduction rate of the initial friction coefficient μi of the example and the comparative example 2 when compared with the comparative example 1.

  As shown in Table 2, the segment wet friction material 1 according to the example in which the papermaking groove 4 was formed in any of the oil temperatures of 40 ° C., 80 ° C., and 120 ° C. was compared with the conventional press groove formed. It was found that the effect of reducing the initial friction coefficient μi was almost the same as that of the segment wet friction material according to Example 2.

  Thus, in the wet friction material 1 according to the present embodiment, the press groove is reduced to reduce the manufacturing process cost and shorten the time, and the comparative example 2 in which the oil groove is formed by the press is applied. As in the case of the segment wet friction material, the papermaking groove 4 serving as an oil groove can be formed on the surface of the friction material base with higher accuracy, and excellent friction characteristics can be reliably obtained.

  Next, a wet friction material according to a modification of the present embodiment will be described with reference to FIG.

  First, the wet friction material 1A according to the first modification of the present embodiment shown in FIG. 5A is a segment according to the above example in step S1 in the manufacturing process of the friction material base material shown in FIG. A straight paper-making groove similar to the paper-making groove 4 of the wet friction material 1 is formed with a narrower interval, and the segment piece 3A is cut out from the finished friction material base so that the paper-making groove 4A is in the lateral direction. (Spun), the segment piece 3A is bonded to the both sides of the cored bar 2 with two 2 mm wide segment grooves 5 in the same manner as the segment wet friction material 1 according to the above embodiment.

  Thus, by providing the papermaking groove 4A along the circumferential direction of the wet friction material 1A, a segment wet friction material 1A having friction characteristics different from the segment wet friction material 1 according to the above embodiment can be obtained. .

  Further, the wet friction material 1B according to the second modification of the present embodiment shown in FIG. 5B is the same linear papermaking in step S1 of the friction material substrate manufacturing process shown in FIG. A groove is formed, and the segment piece 3B is cut out (punched) from the finished friction material base material so that the papermaking groove 4B is inclined, and the segment piece 3B is the same as the segment wet friction material 1 according to the above embodiment. Further, 20 mm of segment grooves 5 each having a width of 20 mm are formed on both sides of the cored bar 2 and bonded.

  Thus, by providing the papermaking groove 4B oblique to the radiation direction of the wet friction material 1B, the friction different from the segment wet friction material 1 according to the above embodiment and the segment wet friction material 1A according to the first modified example. It can be set as the segment wet friction material 1B which has a characteristic.

  Further, the wet friction material 1C according to the third modified example of the present embodiment shown in FIG. 5C is a curved wave-shaped papermaking in step S1 of the friction material substrate manufacturing process shown in FIG. A groove is formed, and the segment piece 3C is cut out (punched) from the completed friction material base so that the papermaking groove 4C faces the radiation direction. The segment piece 3C is similar to the segment wet friction material 1 according to the above embodiment. Further, 20 mm of segment grooves 5 each having a width of 20 mm are formed on both sides of the cored bar 2 and bonded.

  Thus, by providing the wave-shaped papermaking groove 4C in the radiation direction of the wet friction material 1C, the segment wet friction material 1 according to the above embodiment, the segment wet friction material 1A according to the first modification, and the second modification. The segment wet friction material 1C having a friction characteristic different from that of the segment wet friction material 1B can be obtained.

  In addition, the wet friction material 1D according to the fourth modification of the present embodiment shown in FIG. 5 (d) forms lattice-shaped papermaking grooves in step S1 of the friction material substrate manufacturing process shown in FIG. Then, the segment piece 3D is cut out (punched) from the completed friction material base so that the lattice-shaped papermaking grooves 4D are inclined with respect to the radiation direction, and the segment wet friction is applied to the segment piece 3D according to the above embodiment. Similarly to the material 1, 20 pieces of segment grooves 5 each having a width of 2 mm are formed on both surfaces of the core metal 2 and bonded.

  Thus, by providing the grid-like papermaking grooves 4D in the wet friction material 1D, the segment wet friction material 1 according to the above embodiment, the segment wet friction material 1A according to the first modification, and the segment according to the second modification. The wet friction material 1B can be a segment wet friction material 1D having friction characteristics different from the segment wet friction material 1C according to the third modification.

  Further, the wet friction material 1E according to the fifth modification of the present embodiment shown in FIG. 5 (e) is a large number of dimple-like papermaking in step S1 of the friction material substrate manufacturing process shown in FIG. A groove 4E is formed, and a segment piece 3E is cut out (punched out) from the completed friction material base. The segment piece 3E is formed on both surfaces of the cored bar 2 in the same manner as the segment wet friction material 1 according to the above embodiment. Each segment groove 5 having a width of 2 mm is opened and bonded.

  Thus, by providing the wet friction material 1E with a number of dimple-shaped papermaking grooves 4E, the segment wet friction material 1 according to the above embodiment, the segment wet friction material 1A according to the first modification, and the second modification are provided. The segment wet friction material 1B, the segment wet friction material 1C according to the third modification, and the segment wet friction material 1E having friction characteristics different from the segment wet friction material 1D according to the fourth modification can be obtained.

  In the present embodiment, the segment wet friction material formed by cutting the segment piece from the friction material base material as the wet friction material and bonding the segment pieces to both surfaces of the flat ring metal core is explained as an example. Segment wet friction material made by adhering segment pieces to only one side of a metal core, or cutting out a ring friction material base from a friction material base and bonding it to both or one side of a flat ring metal core The present invention can also be applied to a ring-shaped wet friction material.

  Moreover, in this Embodiment, although the segment wet friction material formed by adhere | attaching 20 segment pieces on both surfaces of a flat ring-shaped cored bar was demonstrated as an example, the number of segment pieces is more than 20. May be less. In particular, in order to obtain excellent friction characteristics, the number of segment pieces is more preferably in the range of 20 to 40.

  Further, in the present embodiment (example), the case where three papermaking grooves 4 are formed on the surface of the segment piece 3 has been described. However, the number of the papermaking grooves 4 is 1 according to the required friction characteristics. There may be two books or four or more.

  In carrying out the present invention, the configuration, shape, quantity, material, size, connection relationship, etc. of other parts of the wet friction material, and other steps of the method for manufacturing the wet friction material are also implemented. The form is not limited.

FIG. 1 is a flowchart showing a part of a manufacturing process of a wet friction material according to an embodiment of the present invention. FIG. 2A is a partially enlarged plan view showing a part of the wet friction material according to the embodiment of the present invention in an enlarged manner, and FIG. 2B is a partial sectional view showing a section AA in FIG. FIG. 3A is a graph showing drag torque characteristics of a wet friction material (example) according to an embodiment of the present invention when the oil amount is 100 ml / min, compared with the conventional example, and FIG. 3B is an oil amount of 1000 ml. It is a graph which shows the drag torque in the case of / min compared with a prior art example. FIG. 4 is a graph showing the friction coefficient characteristics of the wet friction material (example) according to the embodiment of the present invention when the oil temperatures are 40 ° C., 80 ° C., and 120 ° C., as compared with the conventional example. FIG. 5A is an enlarged partial plan view showing a part of the wet friction material according to the first modification of the embodiment of the present invention, and FIG. 5B is a second modification of the embodiment of the present invention. The partial expanded plan view which expands and shows a part of wet friction material concerning, (c) is the partial enlarged plan view which expands and shows a part of wet friction material concerning the 3rd modification of embodiment of this invention. , (D) is a partially enlarged plan view showing a part of a wet friction material according to a fourth modification of the embodiment of the present invention, and (e) is a fifth modification of the embodiment of the present invention. It is a partial enlarged plan view which expands and shows a part of this wet friction material. FIG. 6 is a flowchart showing a part of the manufacturing process of the wet friction material in the prior art.

Explanation of symbols

1, 1A, 1B, 1C, 1D, 1E Wet friction material 2 Core metal 3, 3A, 3B, 3C, 3D, 3E Segment piece 4, 4A, 4B, 4C, 4D, 4E Papermaking groove 5 Segment groove

Claims (3)

A wet friction material formed by adhering a ring-shaped friction material substrate or a segment piece cut out from a friction material substrate to both sides or one side of a flat ring metal core,
The ring-shaped friction material base is formed by forming a plurality of oil grooves having a predetermined depth and width on the friction material substrate in a paper body state before impregnating the resin of the friction material substrate. A wet friction material, wherein one or two or more oil grooves of a predetermined shape having a necessary depth and width are provided on the surface of the material or the segment piece.   The segment piece has 20 or more and 40 or less per one circumferential surface of the flat ring metal core, and the oil groove having the predetermined shape provided on the surface of the segment piece is 1 or more and 4 or less. The wet friction material according to claim 1. A method for producing a wet friction material obtained by adhering a ring-shaped friction material substrate or a segment piece cut out from a friction material substrate to both sides or one side of a flat ring metal core,
Forming a plurality of oil grooves of a predetermined shape having a predetermined depth and width while or after papermaking the friction material substrate;
Impregnating a thermosetting resin into the friction material substrate in the paper body state;
Heating the friction material substrate impregnated with the thermosetting resin to cure the thermosetting resin to complete the friction material substrate;
Cutting the ring-shaped friction material substrate or the segment piece from the friction material substrate;
A method of manufacturing a wet friction material, comprising: adhering the ring-shaped friction material base material or the segment piece to both surfaces or one surface of the flat ring-shaped cored bar.

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