JP2791857B2 - Mold equipment for bellows production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device for producing bellows such as a protective boot for a suspension which is a shock absorber of an automobile, a protective boot for a rack and pinion type steering device, and a constant velocity joint boot for a driving portion. It is.

[0002]

2. Description of the Related Art Conventionally, in this type of bellows, a short cylindrical opening end is formed at both ends of a cylindrical bellows as described in, for example, Japanese Utility Model Laid-Open No. 60-167259. In addition, an annular protruding portion was formed on the inner peripheral surface of the short cylindrical opening end portion so as to maintain a completely tight fit with the bellows mounting portion.

A blow molding apparatus for forming an annularly projecting rib on the inner peripheral surface of a cylindrical opening of this type of bellows is described in Japanese Patent Application Laid-Open No. 56-69127. In this blow molding apparatus, a mandrel assembly having an annular groove formed on the outer peripheral surface of a mandrel assembly for regulating the inner peripheral surface of the cylindrical opening is inserted into the parison to regulate the inner peripheral surface of the cylindrical opening. An annular rib is formed.

[0004]

As described in Japanese Patent Application Laid-Open No. 56-69127, an annular groove is provided on the outer peripheral surface of a mandrel assembly for regulating the inner surface of a cylindrical opening of a bellows. In the case of inserting an object into the parison and forming an annular rib on the inner peripheral surface of the cylindrical opening, in the step of pulling out the mandrel assembly, the rib is forcibly deformed in the pulling direction, so the rib However, there is a disadvantage that the shape is lost or lost. For this reason, it is difficult to form a rib having a required height on the inner peripheral surface of the cylindrical opening, and it has been impossible to manufacture a bellows having high sealing properties.

In addition, the mandrel assembly must be inserted into the parison for each molding, and the mandrel assembly must be removed after blow molding, resulting in a complicated operation and low productivity.

The present invention has been made in view of the above-mentioned problems in the prior art, and does not require the use of a core mold such as a conventional mandrel assembly even in a mold apparatus for producing a bellows by blow molding. An annular ridge of the required shape and height can be formed with high precision on the inner peripheral surface of the bellows cylindrical mounting part, has excellent sealing properties, and easily inserts the cylindrical mounting part into the mounting part. It is an object of the present invention to provide a mold apparatus for producing a bellows which is completed and has excellent workability for mounting.

[0007]

In order to achieve the above object, a bellows manufacturing die apparatus according to the present invention has a cylindrical mounting portion at both ends of a cylindrical bellows portion. A concave portion for tightening the flat belt is formed on an outer peripheral surface of the cylindrical mounting portion, and an annular protruding portion is formed on an inner peripheral surface of the cylindrical mounting portion. A mold device for molding a bellows formed by forming a deep groove-shaped annular concave groove in the outer surface of a cylindrical mounting portion, comprising a pair of split molds, in a cavity on an inner surface of the pair of split molds. An annular projection is provided on the surface to form a recess, and an annular projection is further provided on the annular projection to form an annular groove.

[0008]

In the mold apparatus for manufacturing the bellows according to the present invention, the cavity on the inner surface of the pair of split molds is
An annular protrusion that forms a concave portion is provided on the outer peripheral surface of the cylindrical mounting portion, and an annular protrusion that further forms an annular concave groove is provided on the annular protrusion. A concave portion is formed on the outer peripheral surface of the attachment portion by an annular protrusion, and an annular groove is formed by an annular protrusion. On the inner peripheral surface of the cylindrical mounting portion, resin rises around the annular protrusion. Thus, an annular ridge is formed.

According to the present invention, the resin is raised around the annular ridge by the annular ridge formed on the annular ridge as described above, and the annular ridge is formed on the inner surface. The resin is moved by the annular ridge formed in the cavity to form an annular ridge without the resin being moved by compression by arranging the mold inside. Therefore, unlike the conventional case, there is no need to use a core mold such as a mandrel assembly inside, so not only can the shape of the tall ridges be formed more accurately, but also the work can be simplified. And high productivity can be obtained.

In the bellows formed as described above, an annular ridge is formed on the inner peripheral surface of the cylindrical mounting portion, and the annular ridge is formed in the concave portion of the mounting portion. Since the annular groove is formed in the part, when inserting the cylindrical mounting part into the mounting part of the bellows, the annular ridge on the inner peripheral surface is expanded by expanding the annular groove from the outside. It is immersed and absorbed in the annular groove, and the inner peripheral surface of the cylindrical mounting portion becomes a smooth surface, so that the insertion can be performed smoothly. Then, when the flat belt is wound into the concave portion of the cylindrical mounting portion after insertion and tightened, substantially the entire surface of the cylindrical mounting portion is uniformly tightened, and the annular ridge of the inner peripheral surface protrudes inward. And the annular ridge is formed in an O-ring shape to maintain a high sealing property of the tubular mounting portion with respect to the bellows mounting portion.

[0011]

1 and 2 show a bellows manufactured by a bellows manufacturing die apparatus according to the present invention. Reference numeral 1 denotes a bellows as a constant velocity joint boot. The bellows 1 has a cylindrical bellows portion 2 and cylindrical mounting portions 3 formed at both ends. On the outer peripheral surface of the cylindrical mounting portion 3, a concave portion 4 for tightening a flat belt described later is formed, and in the concave portion 4, an annular concave groove 5 having a relatively small width and a relatively large depth is formed. . An annular ridge 6 is formed on the inner peripheral surface of the cylindrical mounting portion 3 so as to correspond to the annular groove 5. The annular ridge 6 extends in the axial direction of the cylindrical mounting portion 3. It has a gentle mountain shape. The annular groove 5 has a deep groove shape having a square or rectangular cross section. One of the cylindrical mounting portions 3 at both ends of the cylindrical bellows portion 2 has a large diameter, and the other has a small diameter.

FIGS. 3 and 4 show a mold apparatus 7 for manufacturing the bellows 1. The mold device 7 includes a pair of split molds 8, 8. In the inner surface cavities of the pair of split molds 8, 8, a portion where the large-diameter cylindrical mounting portion 3 is formed is provided. An annular protrusion 9 is formed on the outer peripheral surface of the cylindrical mounting portion 3 to form the concave portion 4. The annular protrusion 9 further has a square or rectangular annular cross section for forming the annular concave groove 5. A ridge 10 is provided. In addition, since the part forming the cylindrical attachment part 3 on the small diameter side has the same configuration, the description thereof is omitted.

The blow molding of the bellows 1 by the mold apparatus 7 is shown in FIG. As shown in FIG.
A tubular mounting portion 3 is formed in the bellows 1 to be blow-molded, and a concave portion 4 is formed on an outer peripheral surface of the cylindrical mounting portion 3 by an annular protrusion 9. Thereby, an annular groove 5 is formed. At this time, a portion corresponding to the annular ridge 10 bulges inward on the inner peripheral surface side of the cylindrical mounting portion 3, and the annular ridge 6 is formed in a gentle mountain shape. Note that a chain line a indicates a cut line after molding, and 11
Denotes a bulging burr portion.

As shown in FIG. 5, the blow molded bellows 1 is taken out by opening a pair of split molds 8,8. At this time, since the annular projection 9 and the annular ridge 10 move in the opening direction of the recess 4 and the annular groove 5 formed in the bellows 1, the annular projection 9 and the annular ridge 10 are moved.
Is smoothly removed from the recessed portion 4 and the annular groove 5 and does not deform or lose them. Therefore, the annular groove 5 can be formed to have a required shape and depth, and the annular groove 5 can be formed into a deep groove.

FIGS. 6 and 7 show a constant velocity joint 12.
2 shows an embodiment in which the bellows 1 is mounted. That is, reference numeral 13 denotes a boot mounting portion (large diameter side) of the constant velocity joint 12, and the bellows 1 is mounted by inserting the tubular mounting portion 3 thereof. At the time of this insertion, the annular ridge 6 on the inner peripheral surface of the cylindrical mounting portion 3 is pushed in the outer peripheral direction by the outer peripheral surface of the boot mounting portion 13. The protruding portion of the protruding portion 6 is depressed and absorbed, and the inner peripheral surface of the cylindrical mounting portion 3 becomes smooth.
For this reason, the insertion of the tubular mounting portion 3 of the bellows 1 is performed smoothly. Next, if the flat belt 14 is wound around the concave portion 4 of the cylindrical mounting portion 3 and tightened, the entire surface of the cylindrical mounting portion 3 is uniformly tightened, and the annular groove 5 is compressed in the inner circumferential direction. The annular protruding portion 6 which has been depressed is pushed out toward the inner peripheral surface side, so that the uniform tightening action of the flat belt 14 and the sealing action of the annular protruding portion 6 are combined to provide a high O-ring shaped seal. Nature is maintained. Therefore, the hermeticity inside the bellows 1 is perfect.

The bellows shown in FIGS. 1 and 2 manufactured by the mold apparatus according to the present invention will be described below with reference to specific numerical examples.

Cylindrical mounting portion (large diameter side) Diameter 48 mm Same (small diameter side) Diameter 12 mm Width of concave portion (W) 9.5 mm Same depth (D) 2.5 mm Width of annular groove (w) 0. 5mm Same depth (d) 2mm Maximum height of annular ridge (h) 1.5mm

According to an experiment conducted by the inventor, it has been found that the sealing performance varies depending on the shape of the annular groove 5. The width w of the annular groove 5 is in the range of 0.3 to 0.75 mm and the depth d
1 to 3 mm satisfied the sealing strength and mounting workability required by the bellows. The width W and the depth D of the recess 4 need not be considered as long as the flat belt can be accommodated. Here, the thickness of the cylindrical mounting portion 3 may be 0.5 to 2.5 mm, preferably 1 to 2.5 mm.
2 mm.

The bellows 1 is a single-layered body made of a single material of a thermoplastic synthetic resin such as various elastomers such as polyolefin, polyester, polyurethane, polyamide and styrene, and soft polyvinyl chloride having a high rubber elasticity. Or a multilayer body obtained by appropriately combining them or a single layer body or a multilayer body composed of a composition obtained by blending a plurality of these. In particular, the bellows 1 according to the present invention has a compression set (JIS K6301) of 75.
It has been found that the use of a rubber-rich constituent material of not more than 72%, preferably not more than 72%, has a remarkable effect on seal strength and mounting workability.

In the bellows shown in FIGS. 1 and 2, concave portions 4 and annular concave grooves 5 are formed in cylindrical mounting portions 3 at both ends of the cylindrical bellows portion 2.
And the annular ridge 6 are formed, but the invention is not limited thereto. For example, by forming at least one end of the cylindrical mounting portion 3 according to the shape of the mounted member, a higher effect can be exhibited. The annular groove 5 and the annular ridge 6 formed in the recess 4 are one in the embodiment shown in FIGS. 1 and 2, but may be two or more.

[0021]

According to the present invention, it is not necessary to use a core mold such as a conventional mandrel assembly even in a mold apparatus for producing a bellows by blow molding, and a cylindrical mounting portion for the bellows is provided. An annular ridge having a required shape and height can be formed with high precision on the inner peripheral surface of the mold, and a mold apparatus for manufacturing a bellows which is simple and has high productivity can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall front view showing an example of a bellows manufactured by a mold device according to the present invention.

FIG. 2 is an enlarged sectional view of a part of FIG.

FIG. 3 is a cross-sectional view of a pair of split molds constituting the bellows manufacturing mold apparatus according to the present invention.

FIG. 4 is an enlarged sectional view of a part of FIG.

FIG. 5 is a partial cross-sectional view illustrating a bellows molding mode.

FIG. 6 is a partial cross-sectional view showing an aspect of a bellows mounting process.

FIG. 7 is a partial cross-sectional view showing a mounting state of a bellows.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bellows 2 Cylindrical bellows part 3 Cylindrical mounting part 4 Depression part 5 Annular groove 6 Annular protruding part 7 Mold device 8, 8 A pair of split molds 9 Annular protrusion 10 Annular protrusion 12 Constant velocity joint 13 etc. Speed joint boot mounting part 14 Flat belt

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI B29L 23:00 31:30 (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 33/00-33/76 B29C 49/48 F16J 3/04 F16J 15/52 B29K 21:00 B29L 23:00 B29L 31:30

Claims (1)

(57) [Claims] 1. A cylindrical bellows portion having cylindrical mounting portions at both ends thereof, a concave portion for fastening a flat belt is formed on an outer peripheral surface of the cylindrical mounting portion, and an inner peripheral surface of the cylindrical mounting portion is formed. Is a mold device for forming a bellows having an annular ridge formed therein and forming a deep groove-shaped annular groove in a portion corresponding to the annular ridge in a concave portion of the cylindrical mounting portion. A pair of split molds, and a cavity on the inner surface of the pair of split molds is provided with an annular projection that forms a recess on the outer peripheral surface of the cylindrical mounting portion;
A mold device for manufacturing bellows, wherein an annular ridge for forming an annular groove is further provided on the annular projection.