JPH0291294A - Production of friction material - Google Patents

Abstract

PURPOSE:To enhance utilization ratio of base paper and obtain a friction material without orienting properties of fibers by punching an annular cardboard formed by using a sheet forming mold having an annular sheet forming part having dimensions close to those of a product into an annular shape of prescribed dimensions. CONSTITUTION:A dispersion is formed into a sheet of paper in a sheet forming mold 1 having an annular sheet forming part 7 having dimensions close to those of a product so as to nearly perpendicularly pass the dispersion through a net 5 of the sheet forming mold. The resultant base paper is then punched to produce the product. In the process, the amount of useless parts formed in the base paper is extremely reduced and a molded product having a good dimensional accuracy is obtained without increasing the production man-hour.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a friction material used as a tarlatch facing material in a power transmission mechanism of an automobile or machine, and in particular, it relates to a method for producing a friction material used as a tarlatch facing material, etc. The present invention relates to a method for producing a friction material, which improves the utilization rate of raw materials.

[Prior Art] This type of friction material has conventionally been produced by dispersing fibers such as cellulose, diatomaceous earth and metal oxides as pore regulators, cashew dust, carbon powder, etc. as friction regulators in water, and stirring the mixture thoroughly. It is manufactured by wet paper making from a dispersion liquid.
It is also sometimes called a wet friction material. In addition, as a fiber,
Aromatic polyamide 1Ali fibers (Japanese Patent Publication No. 60-23774, 60-23775), carbon tAll fibers (Japanese Patent Publication No. 60-40834), ceramic fibers (Japanese Patent Publication No. 50-18539), etc. are added to cellulose fibers. It is also known that

For this wet paper making, an ordinary Fourdrinier paper machine, cylinder paper machine, short wire paper machine, etc. are used.

The base paper (paper base material) obtained by this papermaking process is impregnated with a phenolic resin, dried, and then punched into a ring shape, or is punched out into a ring shape and impregnated with a resin.

The ring-shaped friction material thus obtained is bonded to a ring-shaped iron plate, pressed and molded, and then finished to form a clutch plate.

By the way, since the ring-shaped friction material is punched out from the base paper in this way, the utilization rate of the base paper is low. As a solution to this problem, the ring is divided into parts and punched out, and the divided parts (for example, quarter parts) are connected together using an engaging tool, or they are connected (butted together) as they are to form a ring-shaped friction material, which increases the utilization of paper. A method has also been proposed to increase the
issue.

No. 62-80316).

[Problems to be Solved by the Invention] As mentioned above, in the conventional manufacturing method of friction materials, a Fourdrinier paper machine, a cylinder paper machine, a short wire paper machine, etc. are used in wet paper making. When such a paper machine is used, fibers are oriented in the longitudinal direction (the direction in which the paper machine net moves) during paper making.

The friction material obtained by punching from base paper with oriented fibers has different elasticity in the longitudinal direction (fiber orientation direction) and transverse direction (orthogonal direction to the IA fiber orientation direction), and has less elasticity in the longitudinal direction. It is small and has large expansion and contraction in the lateral direction. As a result, the molded friction material tends to have an elliptical shape, and its dimensional accuracy tends to be low.

Further, when punching out a ring shape from base paper, there is a problem that many parts become unnecessary and the utilization rate of the base paper is low.

As in JP-A-62-49034 and JP-A-62-80316, when a ring is divided and punched and the divided bodies are connected to form a ring-shaped friction material, the utilization rate of base paper is increased, but the splitting Flange and fluff are likely to occur at the abutting portions of the bodies, and steps and gaps occur in the abutting portions, impairing the homogeneity of the friction material. Further, it is necessary to perform work to bring the divided bodies together, which takes extra man-hours and increases costs.

The present invention solves the above-mentioned conventional problems and provides a method for manufacturing a friction material that eliminates fiber orientation and improves the dimensional accuracy of molded products, as well as increases the utilization rate of base paper and reduces manufacturing costs. The purpose is to

[Means for Solving the Problems] The method for manufacturing a friction material of the present invention relates to a method including the step of manufacturing a base paper by paper-making a dispersion of a raw material containing fibers. In the present invention, a papermaking mold having a ring-shaped papermaking section with dimensions close to the product is used, the dispersion is made into a ring-shaped base paper using the papermaking mold, and a ring-shaped friction material product is obtained from this base paper. It is characterized by

[Function] According to the method of the present invention, when paper is made from the dispersion using a papermaking die, the papermaking die is not moved in one particular direction of the mesh surface. Therefore, fiber orientation does not occur in the base paper obtained by papermaking. Therefore, the stretchability of the base paper in the vertical and horizontal directions becomes equal, and the dimensional accuracy of the molded product improves. In the present invention, the paper-making die for making paper from the dispersion liquid is not moved in one particular direction within the plane of the mesh surface during paper-making. For example, in many cases in the present invention,
The paper mold remains stationary throughout paper making, and the dispersion passes through the mesh of the paper mold in a substantially orthogonal direction.

During this papermaking process, when the papermaking die moves eight times in one particular direction of the mesh surface, fiber orientation occurs in the base paper obtained by papermaking. During papermaking, even if the papermaking die is stationary, the dispersion passes through the papermaking section obliquely to the mesh surface, and this oblique direction remains unchanged throughout the papermaking process. Fiber orientation occurs in the resulting base paper. In the present invention,
When making paper, it is preferable that the mesh surface of the paper-making section of the paper-making mold be horizontal and that the dispersion liquid pass through this paper-making section vertically.

In addition, in the present invention, the base paper itself obtained by papermaking has a ring shape that is almost the same as the product shape, so when punching out this base paper to obtain a product, the amount of unnecessary parts generated in the base paper is extremely small, reducing material costs. This can be reduced. and,
Since the number of manufacturing steps does not increase, the manufacturing cost of the friction material is reduced.

[Example 7] The present invention will be described in further detail below with reference to the example method shown in the drawings.

FIG. 1 is a process diagram for explaining an example method, FIG. 2 is a plan view of a paper-making mold, and FIG. 3 is a sectional view taken along the line Ⅰ-III in FIG. 2.

First, the configuration of the papermaking mold 1 will be explained using FIG. 2.3. Reference numeral 2 denotes a frame, which in this embodiment has a cylindrical shape with a bottom. A water suction pipe 3 is connected to the bottom 2a of the frame, and the water suction pipe 3 is connected via a valve 4 to a vacuum pump device (not shown). The upper end 2b of the frame 2 has an open opening, and a horizontal mesh 5 is provided between the upper end 2b and the bottom 2a.
is installed. A circular plate 6 is provided in the center of the net 5.
A portion of the net 5 between the outer circumferential edge of the circular plate 6 and the inner circumferential surface of the frame 2 forms a ring-shaped (doughnut-shaped) paper making section 7. This paper making section 7 is set to be larger in circumference than the product dimensions, and the outer diameter of the paper making section 7 is slightly larger than the outer diameter of the product, and the inner diameter of the paper making section 7 is slightly smaller than the inner diameter of the product.

This papermaking mold 1 is set in a papermaking device 9 so as to be vertically movable between a position where it is immersed in a papermaking tank 8 and a position where it is sewn up from the papermaking tank 8 as shown in FIG. A raw material dispersion liquid can be supplied to the papermaking tank 8 from a raw material tank 10 via a raw material transfer pump 11.

To make paper using this paper making apparatus 9, a dispersion liquid in a raw material tank 10 in which valves, inorganic fillers, etc. are dispersed is sifted into a paper making tank 8 by a transfer pump 11.

Next, the papermaking mold 1 is immersed in the papermaking tank 8, and the valve is opened to communicate the inside of the papermaking mold 1 with a vacuum pump device to suck the dispersion liquid. As a result, paper is made only in the paper making section 7, and a ring-shaped mat 12 is formed in the paper making section 7.

Thereafter, the papermaking mold 1 is pulled up from the papermaking tank 8, and the valve 4 is closed. Then, the mat is transferred onto a base plate 14 by a transfer 13, and then pressed and dried to a predetermined thickness by a press dryer 15 to form a base paper 16.

This base paper 16 is ring-shaped with a circumference larger than the target size, and is punched out into a ring shape of a predetermined size to obtain a product friction material.

In the present invention, the raw materials for constituting the friction material are not limited at all, and various materials may be used.For example, in addition to cellulose and asbestos, conventional IA fibers include organic fibers such as aromatic polyamide, carbon fibers, etc. Although inorganic fibers such as ceramic fibers are used, any of these can be used as a raw material in the present invention, and other fibers may also be used.

Further, as the inorganic filler, various fillers such as diatomaceous earth, calcium carbonate, barium sulfate, silica sand, etc., which are friction performance improvers, are used.

Further, before the base paper 15 is pressed and dried, it is usually impregnated with a thermosetting resin. Various types of thermosetting resins, such as phenol resins, can be used as the thermosetting resin. The blending ratio of the fibers and fillers, the concentration of the dispersion, the amount of thermosetting resin impregnated, etc. are not particularly limited.

Note that during press drying using the press dryer, by interposing a spacer with a uniform thickness between the upper press mold and the lower press mold, variations in the thickness of the obtained base paper can be reduced.

In the above explanation, the paper making mold 1 has one ring-shaped paper making part 7, but in the present invention, as shown in FIG. 4, a plurality of ring-shaped paper making parts (four in FIG. ) may also be used. In the case of FIG. 4, the frame 2A is shaped like a rectangular container, and the screen 5 is covered with a partition plate 17. The partition plate 17 has four
A circular plate 6 having a smaller diameter than the opening 18 is concentrically arranged in each circular opening 18,
As a result, a ring-shaped paper making section 7 in which the net 5 is exposed is formed.

By using the papermaking type IA having a plurality of papermaking sections in one frame 2A in this way, the production efficiency of the friction material is improved. Note that the arrangement of the plurality of paper making sections is not limited to that shown in FIG. 4, and the paper making sections may be arranged close to each other so as to form a close-packed arrangement.

Next, specific examples and comparative examples will be described.

Example 1 A friction material was manufactured using the apparatus shown in FIGS. 1 to 3. First, a 6.0 kg valve, a diatom ±
3.0kg and resin 1. A dispersion of Okg in water tooIl was stored.

Next, this dispersion liquid was sifted into a papermaking tank 8, and paper was made using the papermaking die 1 to obtain a ring-shaped mat. This mat was impregnated with 0.7 g of phenol resin in terms of solid content, and then press-dried by holding it at 80° C. for 60 minutes in a press dryer 15 to obtain a base paper 16.

This base paper 16 has an inner diameter of 90 mm and an outer diameter of 130 mm,
The planar area is 69.1 crn''. A friction material having an inner diameter of 100 mm and an outer diameter of 120 mm was manufactured by punching out the base paper, leaving 5 mm on both the inner and outer peripheries.

Since the plane area of this friction material was 34.5 crn', the utilization rate of the base paper reached 50%. (34,5/69.lX
100=50) The shrinkage rate due to press drying was 0.05% in both the longitudinal direction (specific diameter direction of the base paper) and the transverse direction (diameter direction perpendicular to the longitudinal direction). This shrinkage rate is a percentage obtained by dividing the amount of shrinkage due to the press drying process by the diameter value before the press drying process. Since there was no anisotropy in the shrinkage, it was confirmed that the fibers had no orientation.

Comparative Example 1 Paper was made from the same dispersion as in Example 1 using a Fourdrinier paper machine, and press-dried to obtain a rectangular base paper of 130 mm x 130 mm (area: 169 crn"). From this base paper, a minimum punching of 5 mm was left. Inner diameter 100mm, outer diameter 120m
A friction material of m was manufactured. Note that the press drying conditions were the same as in Example 1.

In this case, the utilization rate of the base paper was extremely low at 18%. (34,5/169X100 = Also, the shrinkage rate during press drying is in the longitudinal direction (moving direction of the Fourdrinier in the Fourdrinier machine)
is 0.03%, and the horizontal direction (vertical direction and orthogonal direction) is 0.
．． It was 10%. Since there was significant anisotropy in the shrinkage rate, it was recognized that the fibers were also considerably oriented.

[Effects] As described above, according to the method for manufacturing a friction material of the present invention, a friction material in which fiber orientation is eliminated can be manufactured. A friction material whose fiber orientation has been eliminated in this manner has no anisotropy in shrinkage rate, and therefore has good dimensional accuracy. Furthermore, anisotropy in tensile strength and friction properties is also eliminated.

In the method for manufacturing a friction material of the present invention, a ring-shaped base paper that is slightly larger than the product size is manufactured, so the utilization rate of the base paper is high and material costs can be reduced. Further, it is easy to manufacture, and there is no unnecessary increase in manufacturing man-hours. For these reasons, the manufacturing cost of friction materials can be significantly reduced by the method of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a process diagram explaining the example method, Fig. 2 is a plan view of a paper making mold, Fig. 3 is a sectional view taken along line III-III in Fig. 2, and Fig. 4 is a plan view of a different paper making mold. It is. 1, IA... paper making mold, 6... circular plate, 8... paper making tank, 15... press dryer,

Claims (1)

[Claims] (1) A method for manufacturing a friction material that includes a step of manufacturing a base paper by paper-making a dispersion of raw materials containing fibers, in which a papermaking mold having a ring-shaped papermaking section with dimensions close to the product is used, and the dispersion is A method for producing a friction material, comprising making a ring-shaped base paper using a paper-making die, and obtaining a ring-shaped friction material product from this base paper.