JPS6095120A - Manufacturing method of resonance type muffler made of synthetic resin - Google Patents

Abstract

PURPOSE:To intend shortening of process and accuracy improvement of a resonance type muffler made of synthetic resin by forming a synthetic resin box and an inner pipe into one body with a blow forming die while utilizing small holes of the inner pipe made of synthetic resin. CONSTITUTION:A synthetic resin inner pipe D in which a plurality of small holes d are drilled is heated to about 80 deg.C and inserted and set up in the guide pipe 4' of a slide core 4, then an extruded resin 20 is hung down from the passage 2 of a cross head 1 to outside of the inner pipe D. And the slide core 4 is pinched between the upper pressing unit 3 of the cross head 1 and the lower pressing unit 8 of the slide core 4 by rise of a rod 11 by an air cylinder 9 to retain airtightness. Metal molds 12, 16 for forming the box are moved toward the extruded resin 20 and clamped, then compressed air is supplied from an air flow passge 5 of the slide core 4 through a T-shape flow path 7, annular groove 6 and small holes d of the inner pipe D to form the box through a blow forming process.

Description

[Detailed description of the invention] This application describes a method for manufacturing a resonant silencer made of synthetic resin.

, 4-type silencers are used to reduce noise at specific frequencies from automobile engines and stationary engines, and consist of a box and an inner tube with a small hole inserted into the box. The amount of attenuation is determined by the volume of the cavity formed by the inner tube and the box, the total area of the plurality of small holes, the thickness of the inner tube, etc.

As a conventional example, there is Japanese Utility Model Application Publication No. 56-8848 by the same applicant, and the resonance type muffler A of this publication has a plurality of parts in a box B having a cavity C of a predetermined volume, as shown in Part 1. Insert and fix the inner tube with the small hole d drilled, and connect the small hole d and the cavity C.
It has a structure that communicates with

However, when trying to make an integral resonance type muffler A as shown in Fig. 1 made of synthetic resin as a weight reduction measure, it is difficult to manufacture a structure with a small hole d in the inner pipe. The publication discloses that the resonant silencer A shown in Fig. 1 is made of synthetic resin and is divided vertically into two parts from the center of the small hole d in the figure, and only the box part is welded to form a plurality of parts. A resonance type muffler is proposed which is provided with an unjoined inner tube having a gap corresponding to the total area of the small holes d.

However, in the synthetic resin resonant silencer proposed by this proposal, welding of the box body is possible only when the box body is a perfect circle when using a spin welding machine, and the box body can be welded by vibration welding, hot plate welding, etc. Even if welded, an error occurs in the gap area of the inner tube corresponding to the area of the small hole d, resulting in a difference in resonance frequency, which has the drawback of interfering with the noise damping function.

In view of the above, this application inserts a box as shown in Figure 1 and 2r7I (the inner tube with nine small holes and the box are integrated, and according to the volume of the cavity). The manufacturing of a synthetic resin resonant 'd'!/I'l tf device with a free-form box body; The inner tube is heated in a blow molding machine, which is also called blow molding or hollow molding, and is airtightly erected at both ends. (Abbreviation) is hung down to a predetermined length, a mold for forming the box body is clamped, compressed air is forced into the mold through the small hole in the inner tube, and the inner tube and the box body are integrally welded. Examples will be described below with reference to the drawings.

3 and 4 are sectional views of main parts for explaining the manufacturing method of the synthetic resin resonance type muffler A shown in FIGS. 1 and 2, and the molding machine is generally used. Taking an extrusion type blow molding machine as an example, only the related structure and Ja structure will be explained.

This extrusion type blow molding machine 10 includes a cross rad 1 having a flow path 2 for extruded resin 2o, a slide core 4 having an air flow path 5 for pressurized air, and a mold 12.1 for molding a box B.
Consists of 6.

The crosshead l has an upper presser tllI 3 (11n) for maintaining airtightness at the end of the white edge, and the tip of the air flow passage 5 of the slide core 4 has an annular groove 6 and a '1'' shape communicating with the iR6. There is a guide cylinder 4' provided with a flow path 7, and a lower pressing part 8 of the lower part 1'+J of the inside 1'''i1) is provided (A11).The slide core 4 is also slid to the upper side. For example, the rod 11 of the air cylinder 9 is fixed to the slide core 4.

The mold 12.16 for molding the box B does not necessarily have a symmetrical configuration, but the cavity 13.1 for molding the cavity C of the box B
7 is provided so that the mold is sealed airtight,
Furthermore, the mold 12.16 has a cutting section 14.15.18.1.
9 is molded.

Next, the manufacturing method and effects will be explained.

First, a plurality of small holes d are drilled to the required length, an inner pipe with a thickness t is made using a synthetic resin odor molding machine, the inner pipe is heated to, for example, about 80°C, and a slide core is formed. Insert and stand up the guide tube 4' of No. 4. There is a slight gap between the inner diameter of the inner tube and the outer diameter of the guide 1.1i 4', and the small hole d of the inner tube and the annular groove 6 of the guide tube 4' are at almost the same position. It has become. Then, the extruded resin 20 is suspended from the passage 2 of the crosshead 1 to the outside of the inner pipe, and the slide core 4 is moved to the opening/I door 11 by the operation of an air cylinder 9, for example.
, both ends (upper and lower ends) of the inner tube 4 are connected to the crosshead 1.
The slide core 4 is sandwiched between the upper pressing part 3 and the lower pressing part 8 of the slide core 4 to maintain airtightness. When the extruded resin 20 hangs down for a predetermined length, the molds 12, 16 for forming the box B automatically move toward the extruded resin 20, and the molds are clamped. When mold clamping is completed, compressed air of, for example, about 7 to 9/all flows from the air flow passage 5 of the slide core 4 through the T-shaped flow passage 7, the annular groove 6, and the small hole d in the inner pipe. The extruded resin 20 is placed in the mold 12
．． 16 empty room 13. Press it to the 17 side. Pressure J of compressed air is evenly applied to the semi-fluid extruded resin 20 in the cavity 13.17, which is sealed by mold clamping, and expands into the shape of the cavity 13.17. At this time, the heated inner pipe and the '11 fluid extruded resin 20 are in a welded state, and after the extruded resin 20 is cooled by a mold cooling device (not shown), it is cut by opening the mold 12.16. 14, 15, 18, 19, and the silencer A having the shape shown in FIG. 1 remains on the slide core 4. FIG. 4 is an explanatory sectional view of the main part showing the state f and tung when compressed air is press-fitted into the mold 12 and 16 after the mold clamping in the above step.

After opening the mold, the slide core 4 is stopped by lowering the rod 11 of the air cylinder 9, for example, and the cooled and solidified product is removed, thereby completing one stroke. In the resonance type muffler A manufactured using this row culm, a separation line E is formed on the outer periphery of the box body B by the mold 12.16 shown in Fig. 2, but the appearance is inferior to that of 1 and the airtightness is not good. Complete.

As described above, the present invention utilizes the small holes in the inner tube made of synthetic resin to integrally mold the synthetic resin box and the inner tube by blow molding. , and a cavity having the required volume can be made with a free mold shape, so a resonance type muffler with stable function can be obtained and the number of man-hours can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a resonant silencer, FIG. 2 is a side view thereof, and FIGS. 3 and 4 are sectional views of essential parts for explaining the method of the present application. I...Crosshead 4...Slide core 5...Air flow path 12.16...
Mold 20... Semi-fluid extruded resin A... Resonance type muffler B... Box D...
...Inner pipe d...Small hole shaft H (18 Chichijo Company Shizai Seisakusho)

Claims (1)

[Claims] In the manufacturing method of a resonance type muffler, in which a small hole is formed in a synthetic resin inner tube with openings at both ends, and a synthetic resin box is provided on the outside of the hole, the inner tube Q) communicates with the inside of the small hole. The warmed inner tube is set upright on a slide core provided with an air flow passage, and a paddle-shaped semi-fluid 1 raw extruded resin is suspended from a crosshead to a predetermined length on the outside of the tube. After raising the slide core and pressing the inner tube against the crosshead, and keeping both ends airtight, the mold for forming the box is clamped, and compressed air is forced in from the inside of the small hole to form the box. Molded,
1. A method for manufacturing a resonant sounding instrument made of synthetic +3J resin, characterized in that the inner tube and the box body are integrally welded.