JPH02235719A - Manufacture of foamed rubber molding - Google Patents

Abstract

PURPOSE:To form a foamed rubber molding having uniform cross-section by a method wherein un-vulcanized rubber formed body is conveyed gravitationally during vulcanizing foaming process by being given vibration under the condition that the conveying direction of the un-vulcanized rubber molding is sloped downwards. CONSTITUTION:Un-vulcanized rubber molding, which is extruded from an extruder 1, is guided to work conveying guides 4, to each of which a vibrator 8 on the market having the vibration frequency of 15Hz and the vibration amplitude of 0.4mm is connected so as to transmit its vibration to work 7 guided with the guide 4 in order to vibrate the work 7 too. After extrusion, the work 7 is heated by ultrahigh frequency in a UHF furnace 2. In case that a conveying path 6 is tilted by 24 degrees from the horizon, the work 7 is applied by the components, which is along the conveying path 6, of the force of gravity. At the same time, the frictional resistance between the work 7 and the guide 4 becomes small due to vibration, resulting in conveying the work 7 by means of said component along the conveying path 6. Accordingly, since the work 7 is brought into the state without load and resistance, neither slagging nor elongation occurs in the work and the work is conveyed in accompany with the expansion at foaming.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a foamed rubber molded article such as a weather strip for an automobile.

[Prior Art] For example, in order to manufacture weather strips for automobiles, a third
As shown in the figure, first, an elongated unvulcanized rubber molded body 200 having a constant cross section is formed from unvulcanized rubber by extrusion molding 1100. Continuing with the extrusion molding, the unvulcanized rubber molded body 200 is conveyed by conveyors 300 and 301 while being transferred to an ultra high frequency heating furnace (hereinafter referred to as a UHF furnace) and a high temperature heating furnace (hereinafter referred to as an HAV furnace) 500. By passing it through, it is foamed and vulcanized.

By the way, when an unvulcanized rubber molded body is foamed, its volume expands not only in the radial direction but also in the longitudinal direction. Therefore, if the conveyance speeds of the conveyor 300 and the conveyor 301 are the same, slack will occur on the conveyor 301 due to elongation of the unvulcanized rubber molded body.

Therefore, considering this longitudinal extension, the UHF furnace 40
For a transport speed of the conveyor 300 of 0, the HAV furnace 50
The conveyance speed of the 0 conveyor 301 is set to 1.2 to 1.4 times.

[Problems to be Solved by the Invention] If the conveyance speed of the conveyor 301 is lower than the above range, the unvulcanized rubber molded body 200 will have a UHF furnace 400 and a HAV furnace 5.
00 or inside the HAV furnace 500, and when it becomes larger than the above range, the bowing force acts and stretches, causing a change in the cross-sectional shape. If it is within the above range, loosening will be prevented and the tensile force will be small.

However, the unvulcanized rubber molded body is foaming and elongating every moment inside the UHF furnace 300 and the HAV furnace 400.

For this reason, the stretchers are partially different in the transport direction. That is, when the speeds of the conveyors 300 and 301 are constant, the unvulcanized rubber molded bodies on the conveyors become partially loosened or stretched. For example, HAV furnace 4
If the conveyance speed is set to follow the amount of elongation at the center of 00, a tensile force will act near the inlet, and slack will occur near the exit. Therefore, even in the above-mentioned conventional manufacturing method, the cross-sectional shapes of the foamed rubber molded products obtained are partially different when viewed microscopically. In weather strips and the like, if the cross-sectional shape is partially different, the sealing performance may be affected.

In order to prevent such problems, it is preferable to change the conveyance speed within the furnace substantially continuously in accordance with the extent of elongation of the unvulcanized rubber molded body. However, providing a plurality of conveyors leads to an increase in cost, and a single conveyor causes problems similar to those described above, although to a lesser extent.

The present invention was made in view of these circumstances, and
The purpose is to convey it by following the elongation during foaming.

[Means for Solving the Problems] The method for producing a foamed rubber molded article of the present invention includes a molding step of extruding an elongated unvulcanized rubber molded article with a constant cross section, and In a method for manufacturing a foamed rubber molded body, the vulcanization and foaming process involves heating, vulcanizing, and foaming while conveying the unvulcanized rubber molded body in the direction in which the unvulcanized rubber molded body is transported in the downward direction. The feature is that the unvulcanized rubber molded body is conveyed by gravity by applying vibration to the unvulcanized rubber molded body.

The molding process is normal extrusion molding, and can be performed in the same manner as conventionally. In addition, the raw material composition may be the same as before, and I
It can be composed of various rubbers typified by IR and EPDM, foaming agents, vulcanizing agents, and the like.

The vulcanization and foaming process is a process in which the unvulcanized rubber molded body extruded from an extrusion molding machine is heated to foam and vulcanize it. This process is carried out while transporting the unvulcanized rubber molded body, and heating means include ultra-high frequency (UHF) and high-temperature hot air (
Conventionally used means such as HAV> can be used alone or in combination.

The greatest feature of the present invention lies in the transportation method in the vulcanization and foaming process. That is, the conveyance direction of the unvulcanized rubber molded body is tilted in a downward direction, and the unvulcanized rubber molded body is conveyed by gravity by applying vibrations to the unvulcanized rubber molded body.

In the vulcanization and foaming process, the conveyance direction is inclined in a downward direction. Therefore, a component of gravity along the transport direction is generated in the unvulcanized rubber molded body, so that it can be transported by its own weight. Note that the angle of inclination of the transport direction from the horizontal direction is 20~
It is preferable to set it as 30m. When this angle is smaller than 20 degrees, slack tends to occur, and when it is larger than 30 degrees, tensile force tends to act, and in extreme cases, the unvulcanized rubber molded product may break. Note that during transportation, it is necessary to support the unvulcanized rubber molded body so that its longitudinal direction coincides with the transportation direction, but this can be achieved using support means such as guide rollers and rails. Vibrations can be easily imparted to the unvulcanized rubber molded body by vibrating this support means.

Further, vibrations are applied to the unvulcanized molded body. This reduces the resistance between the unvulcanized rubber molded body and the support means, and the unvulcanized rubber molded body is conveyed by vehicle power due to the above-mentioned inclination in the conveyance direction.

Here, the frequency of vibration is approximately 80-120Hz, and the amplitude is 0.
It is preferable to set it as 3-0.5 mm. If the frequency or amplitude is smaller than this range, the resistance becomes large and conveyance becomes difficult, and even if the frequency or amplitude is made larger than this range, the effect will be saturated.

[Operations and Effects of the Invention] In the method for producing a foamed rubber molded body of the present invention, the unvulcanized rubber molded body is conveyed tilted in a downward direction during vulcanization and foaming,
And vibration is given. Therefore, the unvulcanized rubber molded body is subjected to a force due to its own weight along the conveying direction, and the frictional resistance with the supporting means is reduced due to vibration, so that the unvulcanized rubber molded body can be conveyed by gravity.

By appropriately selecting the inclination angle in the transport direction and the vibration conditions depending on the friction resistance between the unvulcanized rubber molded body and the support means, the unvulcanized rubber molded body can be moved with almost no load and no resistance. This makes it possible to transport the foam while following the expansion during foaming.

Therefore, according to the manufacturing method of the present invention, the loosening of the unvulcanized rubber molded product and the elongation due to tensile force that occur conventionally are eliminated, so it is possible to manufacture a foamed rubber molded product with a uniform cross-sectional shape. can.

[Example] Hereinafter, this will be explained in detail using examples.

FIG. 1 shows a schematic configuration of the apparatus used in this example. This apparatus is composed of an extrusion molding machine 1, a UHF furnace 2, and an HAV furnace 3. In the UHF furnace 2 and the HAV furnace 3, workpiece conveyance guides 4 and roller conveyors 5 are alternately arranged in a straight line to form a conveyance path 6. This conveyance path 6 is inclined downward at an angle of 24 degrees with respect to the horizontal direction, and the extrusion direction of extrusion molding@1 is on a straight line with the conveyance path 6.

As shown in FIG. 2, the workpiece conveyance guide 4 guides an unvulcanized rubber molded body (hereinafter referred to as the workpiece) 7 extruded from the extrusion molding machine 1, and the workpiece conveyance guide 4 is guided by a commercially available piburator 8. are connected. The vibrator 8 has a frequency of 105Hz and an amplitude of Q. The structure is such that the vibration is transmitted to the workpiece 7 guided by the workpiece conveyance guide 4 and the workpiece 7 also vibrates.

A foamed rubber material containing EPDM rubber as a main component is supplied to an extrusion molding machine 1, and a workpiece 7 having a cross-sectional shape shown in FIG. 2 is continuously molded. The extrusion speed is about 8 m/min, and the temperature of the workpiece 7 immediately after extrusion is about 85°C.

Immediately after extrusion, the workpiece 7 is heated in the UHF furnace 2 using ultrahigh frequency waves. The ultra-high frequency output is approximately 4 kW. After the workpiece 7 leaves the UHF furnace 2, it enters the HAV furnace 3.
Heat at about 200℃ for about 3 minutes.

Here, the conveyance path 6 along which the workpiece 7 is conveyed is inclined at 24 degrees from the horizontal direction, as described above.

Therefore, a component force of gravity along the conveyance path 6 acts on the workpiece 7, and the component force is s i 24° times its own weight. Roughly speaking, the workpiece 7 is given vibration from the pibrator 8, and the workpiece 7 vibrates within the workpiece conveyance guide 4. Therefore, by photographing the workpiece 7 and the workpiece conveyance guide 4.
The frictional resistance between the workpiece 7 and the workpiece 7 becomes smaller, and the workpiece 7 is transported along the transport path 6 by the above component force. Therefore, the workpiece 7 is in a state with almost no load and no resistance, so that no slack or elongation occurs, and the workpiece 7 is conveyed following the elongation during foaming.

That is, according to the manufacturing apparatus of this embodiment, the workpiece 7 is uniformly foamed without uneven elongation or slack, so that a foamed rubber molded body having a uniform cross-sectional shape is formed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating a manufacturing method according to an embodiment of the present invention, and FIG. 2 is an enlarged explanatory diagram of a main part of a workpiece conveyance section in FIG. 1. FIG. 3 is an explanatory diagram illustrating a conventional manufacturing method. 1... Extrusion molding machine 2... UHF furnace 3... H
AV furnace 4... Work conveyance guide 5... Roll conveyor 6... Conveyance path 7... Work (unvulcanized rubber molded body) 8... Pibrator patent applicant Toyoda Gosei Co., Ltd. agent Patent attorney Hiroshi Okawa

Claims (1)

[Claims] (1) A molding process of extrusion molding an elongated unvulcanized rubber molded body with a constant cross section, and vulcanization foaming in which the unvulcanized rubber molded body is heated, vulcanized, and foamed while being conveyed in the axial direction. In the method for producing a foamed rubber molded body, the vulcanization and foaming step includes tilting the conveying direction of the unvulcanized rubber molded body in a downward direction and applying vibration to the unvulcanized rubber molded body. A method for producing a foamed rubber molded article characterized by transporting it by gravity.