JPS5962772A - Plastic piston for disc brake - Google Patents

Abstract

PURPOSE:To prevent damage of a square seal to roll back the piston or the internal walls of the cylinder by forming a hardened film of thermoplastics of no less than 1mum thick and thereby avoiding exposure of inorganic substance at the surfaces. CONSTITUTION:At the surface of a plastic piston 7 is formed a hardened layer 8 of no less than 1mum thick made of a thermoplastic resin as the matrix. Thereby the surface of piston is protected against corrosion by the brake liquid as well as the sealing material is prevented from damage, which assures well a much improved durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin piston for a disc brake that includes a thermosetting resin containing an inorganic material such as glass fiber.

Recently, pistons made by adding inorganic materials such as glass fiber, mica, carbon fiber, and copper rings to thermosetting resin such as phenol resin have been used for disc brakes. Alternatively, since polishing is applied, the inorganic material 4 such as glass fiber from the thermosetting resin 3 is exposed on the surface 2 of the piston 10, and when the piston slides inside the cylinder, the exposed surface of the piston is Rolling back damaged the corner seal and cylinder inner wall.

Therefore, the present invention is to prevent the above-mentioned drawbacks by forming a cured film of thermosetting resin of 1 μm or more on the surface of the resin piston to prevent the inorganic material from being exposed on the surface.

One embodiment shown in FIGS. 2 and 3 will be described below. A resin piston 7 that is slidably provided in a cylinder 6 formed in a caliper body 5 has a thermosetting resin 3 as a matrix, and an inorganic material 4 was mixed in.

Phenol resin is generally used as the thermosetting resin, but polyamide resin and other appropriate resins can also be used. Ma/ζ Inorganic substances include glass fiber, back matrix,
Although suitable materials such as carbon fiber and copper can be used, expansion of the piston can be suppressed by containing 35% to 50% of glass fiber.

This resin histone 7 has on its surface a hardened layer 8 of 1 μm or more of a thermosetting resin used as a matrix.

An asbestos-based heat insulating plate 10 is fitted to the open end of the resin piston 7 on the side where the pad 9 is pressed.
It is connected to a.

This heat insulating board 10 is made of a molded body composed of 25% to 45% asbestos and 55% to 75% cement in terms of N content ratio.

Note that 11 is a corner seal.

As described above, the present invention forms a hardened layer of thermosetting resin on the surface of the resin piston, so the piston surface is not damaged by brake fluid and the sealing material is not damaged, improving durability. can be 0

[Brief explanation of the drawing]

Fig. 1 is a partially enlarged sectional view of a conventional resin piston, Figs. 2 and 3 show an embodiment of the present invention, Fig. 2 is a sectional front view of a caliper body, and Fig. 3 is a resin piston. FIG. 3 is a partially enlarged sectional view of the piston. 3 is a thermosetting resin, 4 is an inorganic material, 7 is a resin piston, 8
1 is a hardened layer, and 10 is a heat insulating board. Figure 1. 3rd cause, 2nd cause

Claims (1)

[Claims] 1. A disc brake characterized in that a resin piston containing an inorganic material such as glass fiber, mica, carbon fiber, copper, etc. in a thermosetting resin is formed with a hardened layer of thermosetting resin of 1μ or more on the surface of the piston. Resin piston for use.