JPH0433301B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method of manufacturing a braking member used for power transmission and/or braking of automobiles, motorcycles, industrial machines, etc. (Prior Technology) Conventionally, braking members for automobiles, vehicles, various industrial machines, etc. have been made by using a holding member (brake piece) made of light alloy casting or die casting, reinforced with asbestos and using phenolic resin as a binder. Molded products with bonded friction members are widely used. However, the above known braking members have the following problems. Productivity is poor. That is, after polishing and finishing the cast brake piece (brake shoe, etc.),
After applying a primer to the brake shoe side and an adhesive to the friction member (brake lining, etc.) side, the two are pasted together, and then heat cured under pressure (200-300℃ x approx. 30Kg/cm ² , Since each step (about 40 minutes) is done using a clamping jig, productivity is extremely low. Product reliability is poor. That is, in the bonding process, since the surface of the friction member is porous and absorbs the applied adhesive, it is difficult to make the thickness of the formed adhesive layer constant. Therefore, variations in adhesive strength tend to occur, making it impossible to obtain a highly reliable product. Since the brake shoe and other parts are made of metal, they are susceptible to corrosion. This drawback is particularly noticeable when driving on a road surface that has been sprayed with winter snow melting agents. In metal brake shoes, the rotational kinetic energy absorbed by the brake lining is easily converted into vibrational energy, and as a result, unpleasant resonance vibration noise (commonly known as "squeal") is often generated during braking. It is heavy because the brake shoe etc. are made of metal. Therefore, Japanese Patent Application Laid-Open No. 51-69729 discloses reinforcing materials,
A friction pad for a disc brake is described, which includes a friction material fitted and fixed onto the uneven surface of a back plate with an uneven surface (holding member) compression molded from a composition consisting of an anti-friction agent and a thermosetting resin. However, integration with the friction material not only requires high temperatures and pressures, but also requires preheating of the raw material resin, two-stage mold clamping, degassing, and long curing times (usually 1 minute per 1 mm of thickness), there are productivity problems unique to thermosetting resins. Furthermore, simply adding irregularities to the surface of the holding member makes it difficult to completely integrate the molded resin and the holding member, so that the strength of the product against shearing force is likely to be insufficient. (Object of the Invention) The main object of the present invention is to provide a lightweight and highly reliable braking member. A further important object of the invention is to provide a damping member that is resistant to corrosion. Still another important object of the present invention is to provide a method for manufacturing a brake member with excellent productivity, and more specifically, a method for manufacturing a brake member that allows simultaneous bonding and molding with a reduced number of steps. Another object of the present invention is to take advantage of the porosity of friction member surfaces, which was one of the causes of adhesion problems in the past, by press-fitting molten resin into the pores of brake linings, etc. using injection molding. Therefore, it is an object of the present invention to provide a method of manufacturing a braking member in which a holding member and a friction member are firmly integrated by an anchoring effect. Still another object of the present invention is to produce a brake member that is lighter in weight, has superior corrosion resistance, and produces less noise during braking than the conventional metal brake members as described above, using a simple manufacturing process that is easy to automate. The objective is to provide an easy manufacturing method. (Structure of the invention) In order to achieve the above object, the method of the present invention is as follows:
When manufacturing a braking member consisting of a friction member and a holding member such as a brake lining (for drum brakes) or a clutch facing or disc brake pad (for disc brakes), the porosity is 2.
A friction member having a porous surface of ~25% is inserted into a mold, and a thermoplastic resin containing reinforcing fibers is injected into the mold to integrate with the holding member at the porous surface of the friction member. Adopt the configuration. In the above configuration, the friction member is used in brake linings (in the case of drum brakes), clutch facings, and disc brake pads (in the case of disc brakes) in braking parts such as brakes and clutches of automobiles and various other vehicles and various industrial machines. It is a material that is widely used as such. Usually, this material is made using asbestos as a base material, a binder such as phenolic resin, cashew particles, graphite, baryta (barium sulfate), molybdenum disulfide, calcium carbonate, or iron powder to improve wear properties. It is manufactured by mixing various friction modifiers and compression molding the mixture. Preferably, the surface of the upper friction member to be adhered is uniformly sanded in advance to form a certain porous state. The surface has a porosity of 2 to 25%, more preferably 3, in order to enhance the anchoring effect of the molten resin to the adhesive surface in the subsequent injection molding process.
Preferably, it is within the range of ~10%. Incidentally, the porosity mentioned here is a value measured according to a measurement method called the oil impregnation method or the mercury intrusion method [Note]. Note: Oil-impregnated porosity is calculated from the weight increase when a sample is immersed in oil at approximately 90°C for 8 hours, and is expressed as the ratio of increased oil volume to sample volume (%).
will be displayed. Mercury intrusion method porosity is determined by increasing the pressure stepwise from atmospheric pressure to 150,000 psi using a penetrometer, measuring the amount of mercury intruded into the sample pores at each pressure, and calculating the amount of mercury intrusion (cc) in the sample. It is expressed as a percentage, which is the value obtained by dividing by volume and multiplied by 100. If the porosity of the friction member is outside the above range,
For example, if the porosity is less than 2%, the adhesion between the friction member and the plastic molded product that is the holding member will be insufficient, while if it is more than 25%, the strength of the friction member will decrease and the friction performance will be insufficient. It becomes enough,
Neither is desirable for the purpose. In the present invention, there is usually no need for special treatment on the surfaces of the friction member and the holding member to be adhered. However, if the thermoplastic resin compound used as the molding material and the friction member have poor affinity or wettability, a primer or an adhesive may be applied to the surface to be adhered and dried, if desired. The type of primer or adhesive should be appropriately selected depending on the type of molding material used and the required adhesive strength. However, as described above, normally, even without these coating agents, adhesion occurs strongly enough for practical use due to the anchoring effect of the thermoplastic resin on the porous surface (surface to be adhered) of the friction member.
Incidentally, in order to determine whether the degree of adhesion is sufficient, the adhesive surface of the sample is peeled off or fractured by shearing, and then the peeled surface or the fractured surface is observed with the naked eye or using a magnifying glass. As a result, when the fracture surface is a cohesive failure of the friction member, it may be determined that the adhesive strength is sufficient. On the other hand, if there is any evidence of failure at the adhesive interface, a primer or adhesive should be used. In the present invention, the primer used to increase the adhesive strength between the friction member and the braking member is
By being applied to the adhered surface of the friction member, it increases the density of functional groups on the surface and increases the physical affinity with the polar groups of the injected molten resin, or reacts with the functional groups of the molten resin. It is used for the purpose of increasing the affinity of chemical bonds. Specific examples include reactive monomers or prepolymers such as polyisocyanates such as Desmodyur (trade name), urethane prepolymers having polyvalent isocyanate end groups, and polyepoxy compounds such as Epicote (trade name). can be exemplified. Further, as an adhesive used for the same purpose as the above primer, a reactive adhesive composed of the above primer and its reaction partner, an active hydrogen group-containing monomer or prepolymer, is suitable. These reactive adhesives are used in the form of a two-component type containing a catalyst that is active at room temperature, or a one-component type containing a catalyst that is inactive at room temperature and activated at high temperature. In addition,
Rubber cement containing thermosetting resin prepolymers such as rubber-phenol type and rubber-resorcinol type, and rubber cement containing isocyanate can also be used. Thermoplastic resins constituting the holding member of the present invention include nylon 6, nylon 66, polyamide resins such as semi-aromatic special nylon synthesized from metaxylylene diamine and adipic acid, polycarbonate resins, polyethylene terephthalate, polybutylene terephthalate, etc. These are so-called engineering plastics such as polyester resin, polyphenylene sulfide resin, and modified polyphenylene oxide resin. These resins, together with reinforcing fibers and other additives, are processed into a pellet-like compound using a single-screw or twin-screw extrusion kneader. The molding compound obtained here is
After pre-drying and adjusting the moisture content as necessary,
It is supplied from the hopper of the injection molding machine into the barrel of the molding machine, melted and plasticized, and injected into the cavity through the mold gate and sprue at high pressure by a screw or ram, and then cooled and solidified. It is taken out of the mold. The molten resin injected at this time flows into the pores of the friction member previously inserted at a predetermined position in the mold, acts as an anchor, and comes into close contact with the friction member and becomes integrated. Compounds for molding holding members have reinforcing properties in order to give the molded product (holding member) high strength, high rigidity, and high heat distortion temperature, etc., so that they can replace parts in which conventional metal products are used. It must contain fiber. These required physical properties can be satisfied by selecting the thermoplastic resin and reinforcing fibers and adjusting the blending amount of the latter, but in particular, rigidity is extremely important for braking members, and preferably 10 It is desirable to have a bending rigidity of 10,000 ^kgf /cm ² or more. Even with the above-mentioned engineering plastics, it is not possible to achieve a bending rigidity of 100,000 ^kgf /cm ² or more unless reinforcing fibers are blended, so blending reinforcing fibers is an essential requirement for the present invention. As the reinforcing fibers, chopped strands of carbon fibers or glass fibers or potassium titanate whiskers can be suitably used. These reinforcing fibers can be used alone or in combination, and if necessary, aramid fibers,
Other fiber materials such as vinylon, other whiskers such as alumina whiskers, and other inorganic fillers such as mica and wollastonite can also be used in combination. (Effects of the Invention) The effects and advantages of the integrally molded braking member according to the present invention are as follows. Shortening of the manufacturing process Conventional braking members are made into friction members through a number of steps, including casting of the holding metal member → finishing → adhesive application → drying → laminating → crimping → heat curing → removing the clamping jig. Compared to conventional adhesive bonding,
In the method of the present invention, the molding and integral bonding of the parts can be completed in just one step of injection molding of the molding compound, so that the process can be significantly shortened. Improved product reliability Compared to the conventional braking member, which required a long process and was subject to many variations, the braking member of the present invention has a simple manufacturing process, so there is no possibility of poor adhesion or poor bonding. No defects such as poor shape,
Product quality control is easy and reliability is improved. Product weight reduction The weight of the components is approximately 40% lighter than products that use conventional metal holding members. Reducing the weight of this member brings about favorable results for improving the fuel consumption efficiency of automobiles. Reduction in Squeal of Braking Member When the braking member of the present invention was mounted on an actual motorcycle and a braking test was conducted, a significant reduction in squeal was observed. Improved corrosion resistance When the braking member of the present invention and a conventional aluminum die-cast member were immersed in salt water for one week and then taken out and compared, the product of the present invention showed no change, but the aluminum die-cast member showed no change. It had been corroded. This increased corrosion resistance effect is highly desirable, especially for vehicles traveling on coasts and roads sprayed with snow melting agents. Hereinafter, embodiments and effects of implementing the invention will be described using examples, but each example is of course for illustrative purposes and does not mean a limitation on the spirit of the invention. [Example 1] [1] Production of friction member Asbestos, phenolic resin,
Rubber, cashew polymer, baryta, and precipitated calcium carbonate are weighed and mixed, preformed to the dimensions of the lining at room temperature, and heated to 130 to 200°C under high pressure of 100 to 200 kg/ ^cm2 in a mold. did. After molding, to further stabilize the effect of the binder,
Heat treatment was performed at 150-300°C for several hours. The porosity of the obtained friction member was measured by mercury porosimetry and was found to be approximately 8%. [2] Preparation of molding compound According to the formulation shown in Table 1 below, the required amounts of each material were mixed using a blender, and then extruded from a 65 mmφ extruder to form pellets. The extrusion temperature of each material is 1: 270℃, 2: 290℃,
3: 290°C, 4: 260°C, 5: 300°C, 6: 260°C.

【table】

[Table] [3] Injection molding process After drying the pellets obtained in the above process,
Using an injection molding machine equipped with an insert mold,
Injection molding was carried out under the conditions shown in Table 2 below. At this time, the braking member manufactured in [1] was fixed in advance at a predetermined position in the mold, and a test piece as shown in FIG. 1 was created.

[Table] [4] Adhesive performance test The tensile shear adhesive strength of the test piece obtained in [3] above was measured. The state of destruction is shown in Table 3 below and the attached reference photo. (Reference photo (magnification: ×30)
1 shows the fracture state after the fracture test of Example 2, and it is observed that the molding material has penetrated deep into the pores of the lining material. The meanings of the symbols in this photo are the same as those in Figure 2. )

【table】

[Table] [5] Test of physical properties of resin molded parts Test pieces specified by ASTM were injection molded using the pellets of the molding compound obtained in [2] above, and their physical properties were measured. The physical properties of this test piece were determined according to ASTM D638 (tensile) and
The physical properties of the test piece measured according to the D790 (bending) and D648 (HDT) test methods were as shown in Table 2 above. [Examples 7 to 11] Using the molding compound of Example 2, a primer or adhesive coating test was conducted on the surface of a brake member. Other steps are the same as in Example 2. The table below obtained from companies A to E as adhesives-
4. Using the material described in column 1, the adhesive surface of the braking member was coated with a brush. The adhesion test results are shown in Table 4 below.

【table】

【represent.
[Examples 12 and 13] Based on the methods of Examples 2 and 7, a braking member for a 50 c.c. motorcycle was prototyped using an actual mold. The shape of the member is shown in FIG. When the obtained member was mounted on an actual vehicle and test driving braking tests were repeated, no problems were observed in use. In addition, the squeal during sudden braking was clearly improved compared to when conventional metal holding members were used.

[Brief explanation of drawings]

Figure 1 is a side view of a test piece for measuring tensile shear adhesive strength, Figure 2 is Example 12.
and 13 is a side view of a braking member for a motorcycle.
The meanings of the symbols in FIG. 2 are as follows: 1...Thermoplastic resin holding member (brake shoe), 2...Friction member (brake lining).

Claims (1)

[Claims] 1. When manufacturing a braking member consisting of a friction member and a holding member, a friction member having a porous surface with a porosity of 2 to 25% is inserted into a mold, A method of manufacturing a braking member, characterized in that a plastic resin is injected into the mold to integrate the porous surface of the friction member with the holding member. 2. Claim 1, in which the porous surface of the friction member is coated with a primer or adhesive in advance.
Manufacturing method described in section. 3. The manufacturing method according to claim 1, wherein the thermoplastic resin is an engineering plastic.