JPS6231771A - Diaphragm - Google Patents

Abstract

PURPOSE:To prevent the eccentric existence of a ground fabric by making the ground fabric from polyurethane group elastic threads and allowing said elastic thread to possess the tension heat fixation performance at a diaphragm formation temperature, thus permitting the trailing to the material flow by the extension of the ground fabric in throttle shaping. CONSTITUTION:In a diaphragm 1A, the both surfaces of a ground fabric 3A are covered by the high-polymeric elastic layers 4 and 4, and an annular curved part 2 is formed at the intermediate part. The ground fabric 3A is made of polyurethane elastic threads, and said elastic thread possesses tension heat fixation performance at a diaphragm formation temperature. Immediately before the start of material flow in throttling shaping, an annular space 10 in which material does not exist is formed outwardly from the peripheral edge of a blank 5A, and the material flow towards the completion of throttling is generated in the radial direction, and the ground fabric 3A is pulled in the radial direction. Since the ground fabric 3A consists of the elastic threads, also the ground fabric 3A extends, following to the material flow, and the eccentric existence of the ground fabric 3A is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a diaphragm in which both sides of a base fabric are made of polymeric elastic layers and have a constricted portion.

<Prior art> Here, as the diaphragm 1 having a constricted portion, a fifth diaphragm 1 is used.
As shown in FIGS. 1 to 8, an example of an actuator having an annular curved portion (diaphragm portion) 2 will be described, but the present invention is not limited thereto.

Conventionally, in order to mold the diaphragm 1, a blank 5 (unvulcanized in the case of a rubber material) obtained by punching out a laminated sheet material in which both sides of a base fabric 3 are coated with a polymer binder layer 4, As shown in Fig. 6, after setting in the female mold 6, the male mold 7 or the female mold 6 is moved in the mold closing direction, and as shown in Fig. 7, material flow is caused from a shallow constriction just before the start of material flow, and the final Then, the material is squeezed (drawn) and shaped as shown in FIG.

<Problems to be Solved by the Invention> In the above drawing process, as shown in FIG. 7, an annular space 10 that does not exist in the material is created outside the periphery of the blank 5, as shown in FIG. The material flow until the narrowing shown in the figure is completed is in the direction of the annular space 10, that is, in the radial direction, and the base fabric 3 is pulled in the radial direction. At this time, the base fabric 3 is generally made of polyester thread, nylon thread, etc. that does not stretch from the viewpoint of reinforcing properties, and is made of plain weave or knit, so it hardly stretches, or even if it is knit, it is difficult to stretch. The texture of the base fabric is oriented and generally allows the abrasion material to pass through. Therefore, as shown in FIG. 8, the base fabric 3 tends to be unevenly distributed and partially exposed inside the aperture part 2.
This exposure of the base fabric in the diaphragm 1 facilitates capillary penetration of the contacting fluid into the diaphragm, and
It is undesirable because it adversely affects the membrane action of the diaphragm.
If the base fabric is made of stretchable thread such as rubber thread, the base fabric will follow the flow of the material and will not be unevenly distributed, but the elastic return of the thread after the molded product is removed from the mold is large. , "Wrinkles" occur on the membrane surface of the diaphragm, and the rubber thread has a small tensile modulus and the reinforcing properties of the base fabric are insufficient.

<Means for Solving the Problems> As a result of the inventors' earnest efforts in development to solve the above problems, the present inventors have developed a diaphragm in which both sides of the base fabric are made of polymeric elastic layers and has a constricted portion. The inventors came up with the idea of using a base fabric made of polyurethane-based elastic yarn, which has tension heat fixability at the diaphragm forming temperature, and completed the diaphragm of the present invention.

<Operations and Effects of the Invention> The diaphragm of the present invention is produced by the above-mentioned means, when drawing from a blank having polymer elastic layers on both sides of the base fabric, the base fabric is drawn in the radial direction due to the material flow in the radial direction of the blank. Even if the base fabric is stretched, it will stretch and follow the flow of the material, preventing the base fabric from becoming unevenly distributed and being exposed. Since the elastic thread has tension heat fixability at the diaphragm molding temperature, the elastic return of the thread, that is, the base fabric, is small after the molded product is removed from the mold, and wrinkles do not occur on the membrane surface of the diaphragm. The tensile modulus of the polyurethane elastic yarn is 2 to 4 times larger than that of rubber yarn, and the reinforcing properties of the base fabric are also sufficient.

<Example> An example of the present invention will be described below based on FIGS. 1 to 4.

As in the conventional case, the diaphragm IA of this embodiment has a base fabric 3.
Both surfaces of A are made up of polymer elastic layers 4.4, and have an annular curved portion (apertured portion) 2 in the middle portion. In addition to rubber materials such as NBR, EPDM, CO, and ECO, the polymer elastomer also includes thermoplastic elastomers such as urethane and polyolefin.

The base fabric 3A is made of polyurethane elastic yarn, and this elastic yarn has tension heat fixability at the diaphragm forming temperature.

Examples of the above-mentioned polyurethane elastic yarn include:
Manufactured and sold by Azuma DuPont Co., Ltd. under the trademark 'Operon', it is usually 10 to 10 mm thick.
2000D is used. Also, what is tension heat fixability?
It refers to the property that the elastic return of the yarn after tension heat treatment is small, and is quantitatively expressed by the heat fixation rate shown by the following formula, and normally, a yarn with a heat fixation rate of 60% or more is considered to have tension heat fixability.

Heat fixation rate = yarn length after heat treatment / yarn length when tensioned In the case of operon, the rubber diaphragm formation temperature is 180 to 2
At 00°C, the heat fixation rate is about 60-90%. The form of the base fabric 3A is plain weave or knit, as in the conventional case.

Next, a method of forming the diaphragm of the above embodiment will be explained.

After setting a blank 5A obtained by punching out a laminated sheet J material in which both sides of the base fabric 3A made of the polyurethane elastic yarn are coated with polymer elastic layers 4, 4 into a female mold 6 as shown in FIG. , the male mold 7 or the female mold 6 is moved in the mold closing direction, and as shown in FIG. 3, the material flow is caused from a shallow constriction just before the start of material flow, and finally the material is constricted as shown in FIG. ) to form.

At this time, as in the past, immediately before the material flow starts, an annular space 1o where no material exists is created outside the periphery of the blank 5A as shown in FIG. 3, and the material flow until the narrowing is completed as shown in FIG. The base fabric 3A is pulled in the radial direction. However, since the base fabric 3A is made of elastic yarn, the base fabric 3A also stretches following the flow of the material, and the base fabric 3A is not unevenly distributed in the molded product, and there is no risk of the base fabric 3A being exposed. When taken out from the mold, the elastic yarn forming the base fabric has tension heat-setting properties, so the elastic return is small, and "swelling" does not occur on the membrane surface of the diaphragm. Furthermore, since the elastic yarn has a tensile modulus as large as 2 to 4 times that of the rubber yarn, the reinforcing property of the base fabric is also sufficient.

The thus obtained molded product is cut outside the annular rib portion 11 to obtain a diaphragm IA as shown in FIG.

Note that the present invention is not limited to the cross section shown in the figure,
Of course, the present invention can also be applied to diaphragms having other aperture shapes such as a dish shape.

[Brief explanation of drawings]

Figures 1 to 4 illustrate the present invention, Figure 1 is a sectional view showing an example of a diaphragm, Figures 2 to 4 are schematic sectional views of various states during molding of the diaphragm in Figure 1, and Figure 2 shows a blank. When set in the female mold, Figure 3 shows the fourth position immediately before the material starts flowing.
Figures 5 to 8 show the conventional example, Figure 5 is a sectional view showing an example of a diaphragm in which the base fabric is unevenly distributed, and Figures 6 to 8 show the diaphragm molding shown in Figure 5. FIG. 6 is a schematic cross-sectional view of each state, and FIG. 6 shows the blank when it is set in the female mold, FIG. 7 shows the state just before material flow starts, and FIG. 8 shows the state when the squeezing is completed. 1, IA...Diaphragm, 2...Annular curved part (diaphragm part), 3.3A...Base fabric, 5.5A...Blank, 6...Female type, 7...Male type , 10... annular space. Patent applicant

Claims (1)

[Claims] In a diaphragm in which both sides of a base fabric are made of polymeric elastic layers and have a constricted part, the base fabric is made of a polyurethane elastic thread, and the elastic thread has tension heat fixability at the diaphragm molding temperature. A diaphragm characterized by being a thing.