JPH09314036A - Production of gasket having annular seal part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an annular seal part uniform in thickness with reduced manhours at the time of by applying a continuously extruded liquid sealing agent on the surface of a gasket. SOLUTION: A coating starting point 11 is defined as the place out of an annular locus by forming a seal part 13 and the extrusion of the liquid sealing agent is started. Successively the coating work is shifted to the locus for forming the prescribed annular seal part and the circulation coating work is executed >=2 times on the locus for forming the annular seal part. After that, the coating point is shifted to the place out of the locus by forming the annular seal part finish the extrusion and the coating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a gasket in which a continuously extruded liquid sealant is applied to a gasket surface in a predetermined ring shape to form an annular seal portion. The term “annular” does not mean only a circle, but includes an appropriate closed shape in its concept.

[0002]

2. Description of the Related Art When two members having cavities are joined to air-tightly connect the cavities of both members, a gasket is interposed between the members. A through hole is formed in the gasket at a position corresponding to the cavity, and an annular seal portion made of a rubber-like elastic material is formed around the through hole. The seal portion is in close contact with the joint surface of both the members, and plays a role of enhancing airtightness.

The formation of the seal portion is carried out by continuously extruding a liquid sealing agent in a string shape from a dispenser and applying the same to the surface of the gasket. This coating operation is performed by moving the dispenser or the gasket along a predetermined locus for forming the seal portion. If the thickness of the formed seal portion is partially thick or thin, some portions of the seal portion do not come into close contact with the member, resulting in insufficient airtightness. It is important to ensure the airtightness that the annular seal portion has a uniform thickness throughout. In particular, the joint between the application start point and the end point tends to be thick or thin. Conventionally, by controlling the extrusion amount of the sealant from the dispenser and the application speed (moving speed of the dispenser or gasket), the connection part Is not too thick or too thin. In addition, after the applied sealant is cured, a portion that is too thick is scraped off.

[0004]

Since the liquid sealant extruded from the dispenser has a high viscosity, the extruded amount tends to be unstable due to the viscosity at the start and the end of extrusion of the sealant. At the start of extrusion, the increase in extrusion pressure is delayed due to the viscosity of the sealant, so that a slight time delay can be made after the extrusion command is issued and until the predetermined extrusion amount is reached. Even when the extrusion is completed, it takes some time from when the extrusion stop command is issued until the extrusion is actually stopped. As described above, the extrusion amount is not stable at the start and the end of the extrusion of the sealant, which makes it difficult to control the application amount. Therefore, although the amount of extrusion is controlled conventionally, too much or too little amount of coating is unavoidable at the joint between the starting point and the ending point of coating, and the problem of poor airtightness increases. ing. In particular, if the formed seal portion has a high hardness, the seal portion is unlikely to be deformed, so that even if there is a slight variation in the thickness of the seal portion, the airtightness cannot be secured. Further, if the portion of the formed seal portion that is too thick is scraped off by post-processing, it will take too many steps.

The problem to be solved by the present invention is to apply a continuously extruded liquid sealing agent to the surface of a gasket in a predetermined ring shape to form a ring-shaped seal portion. Is to form a uniform seal part.

[0006]

In order to solve the above problems, in the method of manufacturing a gasket according to the present invention, extrusion and coating are started from a position deviated from an annular locus forming a seal portion. Then, the coating operation is moved to a locus that forms a predetermined annular seal portion, and the coating operation that orbits twice or more on the locus that forms the annular seal portion is performed. afterwards,
The extrusion and the application are completed by moving to a position deviated from the locus forming the annular seal portion.

When the gasket having the seal portion is manufactured as described above, the sealing agent is applied to the surface of the gasket in a predetermined manner until the extrusion of the liquid sealing agent is started and the extrusion amount is stabilized to be constant. It will be at a location different from the seal section. In addition, the application of the sealing agent to the gasket surface is made to be at a position different from the predetermined sealing portion until the extrusion of the liquid sealing agent is stopped and until the extrusion is completely stopped. These locations are locations that do not affect the airtightness or are small, so there is no problem even if the coating thickness is reduced. The portions different from these predetermined seal portions may be slightly displaced from the locus forming the predetermined seal portions. On the other hand, application on the locus that forms the predetermined seal part is performed when the extrusion amount of the liquid sealant is constant and stable, so it is possible to form the seal part with a uniform thickness around the entire circumference. become. Further, repeating the coating twice or more on the locus forming the seal portion contributes to uniforming the thickness of the entire circumference. Here, the term “twice or more” does not mean a fraction such as 2.5 times, but an integer such as twice or three times. For example, if the extrusion of the sealant is stopped in the middle of the third orbit and the application is completed by moving to a position deviating from the trajectory forming the seal part, the seal part of the part where the third orbit is not completed is completed. Will be thin.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Extrusion and application of a liquid sealing agent are carried out, for example, by an apparatus as shown in FIG. From the dispenser 1 whose position is fixed, the liquid sealing agent 2 is continuously extruded into a thread shape. On the other hand, the gasket 3 to which the sealant 2 is applied is fixed to the triaxial moving table 4. And
The triaxial moving table is moved so as to draw a predetermined sealing portion in conjunction with the extrusion of the sealing agent, and the sealing agent is applied to the gasket surface in a predetermined shape. The extrusion / stop of the sealant and the operation of the triaxial moving table are controlled by a computer. The sealing agent is nitrile butadiene rubber (NBR), silicone rubber, etc.
The seal portion is completed by heating and curing.
The gasket is a molded product of a thermoplastic resin or a thermosetting resin, or a metal plate such as iron.

In the present invention, extrusion and coating are started from a portion deviated from the locus forming the annular seal portion,
Subsequently, the coating operation is moved to a locus for forming a predetermined annular seal portion, and the coating operation is performed twice or more on the locus for forming the annular seal portion, and then the locus for forming the annular seal portion. Move to a position off the top to finish extrusion and coating. The application of such a sealing agent to the surface of the gasket can take various forms as shown in FIGS. In each of these figures, (a) shows the locus of application, in which the locus of the first application is indicated by a thin arrow and the locus of the second application is indicated by a thick arrow. Although the locus of the first application and the locus of the second application substantially overlap with each other in the portion forming the predetermined seal portion, they are shown in two lines for convenience in the figure for easy understanding. Reference numeral 11 is a coating start point and 12 is a coating end point. Also, in each figure,
(B) shows the shape of the formed annular seal portion 13. From the application start point 11 to the trajectory forming a predetermined annular seal portion, and from the trajectory to the application end point 1
The sealing agent (tail-shaped portion) remaining during the period up to 2 is also shown.

In the embodiment shown in FIG. 1, extrusion and application of a liquid sealing agent are started from outside a predetermined locus forming an annular seal portion. Then, the coating operation is moved to the locus forming the predetermined annular seal portion, and the coating is circulated exactly twice on the locus forming the annular seal portion. After that, extrusion and application of the liquid sealing agent are finished outside the locus forming the annular sealing portion. The locus toward the coating end point 12 is slightly deviated from the locus along the locus forming the annular seal portion to the outside.

In the embodiment shown in FIG. 2, extrusion and application of the liquid sealant are started from the inside of a predetermined locus forming the annular seal portion. Then, the coating operation is moved to the locus forming the predetermined annular seal portion, and the coating is circulated exactly twice on the locus forming the annular seal portion. After that, the extrusion and application of the liquid sealing agent are completed inside the locus forming the annular sealing portion. The locus toward the coating end point 12 is slightly deviated inward from the locus along the locus forming the annular seal portion.

In the embodiment shown in FIG. 3, extrusion and application of the liquid sealing agent are started from the outside of a predetermined locus forming the annular seal portion. Then, the coating operation is moved to the locus forming the predetermined annular seal portion, and the coating is circulated exactly twice on the locus forming the annular seal portion. After that, the extrusion and application of the liquid sealing agent are completed inside the locus forming the annular sealing portion. The locus toward the coating end point 12 is slightly deviated inward from the locus along the locus forming the annular seal portion.

In the embodiment shown in FIG. 4, the extrusion and application of the liquid sealing agent is started from the inside of a predetermined locus forming the annular seal portion. Then, the coating operation is moved to the locus forming the predetermined annular seal portion, and the coating is circulated exactly twice on the locus forming the annular seal portion. After that, extrusion and application of the liquid sealing agent are finished outside the locus forming the annular sealing portion.

[0014]

【Example】

Example 1 A sheet-shaped molding material in which aramid fiber was made into paper together with phenol resin fine particles was heated and pressed to form a gasket having a thickness of 3 mm. By the method described in FIG. 1,
Liquid NBR extruded from a dispenser was applied to the surface of the gasket. NBR when the extrusion is stable
The extrusion rate is set to 0.3g / min and the coating speed is 30mm
/ Sec. After application, NBR was heated at 165 ° C. for 2 hours to be cured to form a seal portion.

Example 2 A 6-6 nylon molding material containing 40% by weight of glass fiber as a filler was injection-molded to mold a gasket having a thickness of 5 mm. Liquid silicone rubber extruded from the dispenser was applied to the surface of the gasket by the method described in FIG. When the extrusion was stable, the extrusion rate of silicon rubber was set to 0.3 g / min, and the coating speed was set to 30 mm / sec. 16 silicone rubber after application
It was heated at 0 ° C. for 1 hour to be cured to form a seal part.

Example 3 A phenol resin molding material containing 40% by weight of glass fiber as a filler was injection-molded to mold a gasket having a thickness of 3 mm. The liquid NBR extruded from the dispenser was applied to the surface of the gasket by the method described in FIG. The NBR extrusion amount, coating speed, and curing conditions were the same as in Example 1, and a seal portion was formed.

Example 4 An iron plate having a thickness of 0.5 mm was used as a gasket. The liquid NBR extruded from the dispenser was applied to the surface of the gasket by the method described in FIG. The NBR extrusion amount, coating speed, and curing conditions were the same as in Example 1, and a seal portion was formed.

Comparative Example Liquid NBR was applied to the gasket surface prepared in Example 1 by the method shown in FIG. That is, liquid N
The application start point 11 and the application end point 12 of BR were placed on a locus forming a predetermined annular seal portion, and the application was performed exactly twice around the locus forming the annular seal portion.
The NBR extrusion amount, coating speed, and curing conditions were the same as in Example 1, and a seal portion was formed.

Table 1 shows the results of measuring the thickness of the seal portion of the gasket manufactured in each of the above examples with a laser thickness gauge. The thickness of the seal portion was measured at the joint portion and the non-joint portion between the coating start point and the coating end point. In the embodiment, the connection point between the application start point and the end point is the point from the actual application start point 11 to the predetermined locus forming the annular seal portion and the actual point from the predetermined locus forming the annular seal portion. It is the joint of the points that deviate from the application end point of. In addition, Table 1 also shows the results of airtightness tests performed on five samples. In the airtightness test, as shown in FIG. 7, a gasket 3 having the seal portions 13 of the above-described examples formed on both surfaces around the through hole 5 is prepared. The gasket 3 is sandwiched between a pair of test jigs 6, and the seal portion 13 is brought into close contact with the test jigs to form a sealed space, and compressed air is supplied to this space to check for air leaks. .

[0020]

[Table 1]

[0021]

As described above, according to the method of the present invention, when a ring-shaped seal portion is formed by applying a liquid sealant continuously extruded in the form of threads onto the gasket surface, the cutting is performed by post-processing. It is possible to form a seal portion having a uniform thickness without performing the above. Good airtightness can be expected even when the material forming the seal portion is hard and its deformation amount is small.

[Brief description of drawings]

FIG. 1 shows a first embodiment of application of a liquid sealant to a gasket surface, (a) is a trajectory of application, and (b) is an explanatory view showing a shape of a formed annular seal portion. Is.

2A and 2B show a second embodiment of application of a liquid sealing agent to a gasket surface, wherein FIG. 2A is an explanatory view showing a locus of application, and FIG. 2B is an explanatory view showing a shape of a formed annular seal portion. Is.

FIG. 3 shows a third embodiment of application of a liquid sealing agent to the surface of a gasket, (a) is a locus of application, and (b) is an explanatory view showing the shape of the formed annular seal portion. Is.

FIG. 4 is a diagram showing a fourth embodiment of the application of a liquid sealing agent to the surface of a gasket, (a) shows the locus of application, and (b) shows the shape of the formed annular seal portion. Is.

5A and 5B show comparative examples of application of a liquid sealing agent to the surface of a gasket, FIG. 5A is an explanatory diagram showing the locus of application, and FIG. 5B is an explanatory diagram showing the shape of the formed annular seal portion.

FIG. 6 is an explanatory view of an apparatus for applying a liquid sealing agent to the gasket surface.

FIG. 7 is an explanatory view showing how a gasket airtightness test is performed.

[Explanation of symbols]

 1 is a dispenser 2 is a liquid sealant 3 is a gasket 4 is a triaxial moving table 5 is a through hole 6 is a test jig 11 is a coating start point 12 is a coating end point 13 is a sealing portion

Claims (5)

[Claims] 1. In the manufacture of a gasket in which a ring-shaped seal portion is formed by applying a continuously extruded liquid sealant on the gasket surface in a predetermined ring shape, the deviation from the locus of forming the ring-shaped seal portion. After starting the extrusion and coating from the location, then moving the coating operation to the locus that forms the predetermined annular seal part, and performing the coating work that goes around the locus that forms the annular seal part two or more times. A method for manufacturing a gasket having an annular seal part, characterized in that the extrusion and the coating are completed by moving to a position deviated from the locus forming the annular seal part. 2. The method according to claim 1, wherein the extrusion and the coating are started outside the locus forming the annular seal portion, and the extrusion and the coating are ended outside the locus forming the annular seal portion. A method for manufacturing a gasket having an annular seal portion. 3. The method according to claim 1, wherein the extrusion and the application are started from the inside of the locus forming the annular seal portion, and the extrusion and the application are ended inside the trajectory forming the annular seal portion. A method for manufacturing a gasket having an annular seal portion. 4. The method according to claim 1, wherein the extrusion and the coating are started from the outer side of the locus forming the annular seal portion, and the extrusion and the coating are ended inside the locus forming the annular seal portion. A method for manufacturing a gasket having an annular seal portion. 5. The method according to claim 1, wherein the extrusion and the coating are started from the inside of the locus forming the annular seal portion, and the extrusion and the coating are finished outside the trajectory forming the annular seal portion. A method for manufacturing a gasket having an annular seal portion.