JPH1073162A - Boots and its molding/extracting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a boot of uniform thickness, which boot is of bellows type and to be mounted on a shift lever of an automobile. SOLUTION: A small port and a large port are formed on both sides of a substantially truncated conical body. A spiral projection 7 and a spiral groove 8 are formed on a peripheral wall of the truncated conical body to obtain a boot 1. The boot 1 is injection-molded by the use of a core 12 having a shape similar to the boot 1, and a longitudinaly dividable die 5 inside which an outer form of the boot is formed. In order for extraction, the small port 2 is rotated to the center of the spiral lines. The die, being a dividable type, enables extraction without damaging the projection 7 of the boot 1. As for the core 12, a large gap is formed by rotating the conical boot 1 for extraction, so that it is unnecessary to strongly press the groove 8 of the boot 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A shift lever, a steering column, a drive shaft and the like of an automobile are provided with a bellows-shaped boot which is inserted into and covers a boot.
The boot is manufactured by molding a molten resin using a mold. The present invention relates to such a boot and a method for forming and removing the boot.

[0002]

2. Description of the Related Art Conventionally, a floor-type shift lever mounted on an automobile has a shaft boot 1 as shown in FIG.
Is installed. The shaft boot 1 is formed in a bellows shape, has a small opening 2 and a large opening 3, and is assembled so that an operation knob of a shift lever projects from the small opening 2.
Although the shaft boot 1 uses a synthetic rubber, a thermoplastic elastomer is frequently used.

The bellows-like portion of the shaft boot 1 can be formed by blow molding, and the process will be described with reference to FIG. First, as shown in FIG. 9A, the bag 4 of synthetic resin in a semi-molten or sufficiently softened state is inserted into the split mold 5, and the bag 4 is inflated by air pressure a. And pressed against the mold wall (FIG. 9 (b)). A plurality of concentric grooves 6 having a substantially uniform depth are formed on a wall surface formed in a substantially frustoconical shape in the mold 5, and the synthetic resin is solidified in close contact with the mold shape and solidified. By opening the mold 5 and discharging the molded product (FIG. 9C), the bellows-like boot 1 having concentric folds having a substantially truncated cone shape is obtained.

By the way, in the blow molding, when air is supplied, there is a possibility that the ridge portion 7 of the boot 1 shown in FIG. This makes the molding operation difficult. on the other hand,
When the boot 1 is to be manufactured by injection molding, a core is used. In this case, the unevenness due to the bellows shape inside the boot and the unevenness on the core surface are engaged, and the hot boot 1 just discharged from the mold 5 is forcibly removed from the core.
Since the projections and depressions are caught by each other, the projections and depressions are rubbed when the projections and depressions get over in the axial direction, and permanent deformation occurs. Therefore, measures such as setting a longer cooling period at the time of discharge are conceivable, but production by injection molding is difficult. In addition, when the core used for injection molding is used as a combination member and the core is taken out of the boot 1, the core is disassembled into a small shape and pulled out so as not to be caught, thereby preventing permanent deformation. It has been proposed (see Japanese Utility Model Laid-Open No. 5-70926). In addition, it has been proposed to integrally mold a pipe joint including a core with a bellows portion having a substantially spiral cylindrical shape (Japanese Patent Application Laid-Open No. Hei 7-27783). The core is disposed between the fixed mold and the movable mold so that the moving direction of the movable mold is perpendicular to the axis of the core. Then, after the molten synthetic resin is injected, the core is rotated like a screw by a motor or the like and removed from the mold, and then the mold is opened, and the pipe joint is formed and discharged. become.

[0005]

By the way, in the blow molding described above, since the mold 5 is not used inside the boot 1,
It is difficult to control the wall thickness, and there is a problem in that loss is increased in order to supply stable quality and production cost is increased. In the above-described injection molding, the thickness can be easily controlled, but since the core is used, there is a possibility that a mark that causes permanent deformation at the time of demolding may be left. For this reason, there is a device in which the former core is used as a combination member, but there is a risk that permanent deformation may remain, and since the structure becomes complicated,
The work is also complicated. Further, in a device for forming a helical pipe joint, two cores are used, and the core of the helical portion is pulled out by being relentlessly rotated like turning a screw, so that workability is poor. In addition, since the inserting direction of the core is orthogonal to the direction of tightening the mold, the structure is complicated and the operation is complicated. Also, the procedure of the blow molding shown in FIG. 9 is significantly different from that of the machine, and the machine is large in size.

SUMMARY OF THE INVENTION An object of the present invention is to provide a boot capable of preventing permanent deformation of a tubular product and controlling the thickness thereof, and a method of forming and removing the boot.

[0007]

According to the present invention, in order to achieve the above object, the boot shape has a helical ridge and a valley groove formed on the peripheral wall of a cylindrical body having a substantially trapezoidal cross section. A spiral bellows is formed in which the front end of the body is a small opening and the base end is a large opening.

Further, as a method of forming the boot, spiral ridges and valleys are formed on the peripheral wall of the substantially truncated cone, and the front end of the truncated cone is a small opening and the base end is a large opening. It is characterized in that a molten synthetic resin is injected between a core and a split mold which is arranged on the surface of the core with a substantially equally spaced gap, and is solidified.

Further, as a method of removing the boot, the boot formed into a spiral bellows is discharged together with the core by the molten synthetic resin injected between the core and the mold. The core is fixed in the boot and the core is rotated toward the center of the spiral.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In a boot according to the present invention, a boot of a substantially truncated cone shape or a substantially truncated quadrangular pyramid shape is attached to a floor type shift lever in accordance with an installation space. Since the boot of this shape has a small mouth at the tip and a large mouth at the base, it is easy to mount since the actuator is inserted from the large mouth when covering the protruding actuator such as a shift lever. The bellows makes it easy to follow the boot even if the actuator is operated arbitrarily.

In the split mold, a central portion is deeply formed to form a recess having a small opening, and the outer shape of the boot is carved. The split mold vertically divides the recess. Then, the core is inserted into the recess from the tip. The position where the gap is at a predetermined interval from any surface of the core is predetermined, and at this position the core is stopped and the thickness of the boot becomes uniform.
Therefore, by changing the size of the core, the thickness of the boot can be controlled. Pressing the injection nozzle against the spout of the mold and injecting rubbery synthetic resin between the mold and the core, the molten synthetic resin flows into the gap,
A boot having a predetermined thickness is formed, and the thickness is made uniform at any location by making the gap uniform. Further, a portion requiring durability, such as a movable portion of a boot, can be formed by increasing the gap at this portion to increase the thickness.

When the pouring from the injection nozzle is completed, the injection nozzle is separated from the split mold and the boot is discharged by dividing the split mold. Since the inside of the boot contains a core, fix the core and rotate the small edge of the boot toward the center of the spiral, so that the boot and the core move relatively apart in the axial direction Therefore, a gap is generated, and the boot can be removed from the core without causing the valley groove of the boot to strongly contact the ridges of the core.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, an apparatus for performing injection molding includes:
In the split mold 5 (5a, 5b), a substantially frusto-conical recess 9 having a large opening 3 on the front side and a small opening 2 on the inner side is formed.
A spiral groove 6 (ridges 6a, valleys 6b) is formed on the wall surface of the concave portion. The pitch of the spiral is substantially the same or gradually increased from the small edge 2 to the large edge 3. The split mold 5 is divided into dies 5a and 5b which divide the substantially spiral recess 9 vertically and move in the radial direction. In addition, although the small opening 2 and the large opening 3 are cylindrical, a flange may be formed.

An injection nozzle is provided on the side of the small opening 2 of the split mold 5.
An inflow port 11 is provided at the ten joints. The core 12 to be interposed in the concave portion 9 having a substantially truncated cone shape is formed in accordance with the shape of the inside of the mold 5, and has spiral grooves (ridges 12a, valleys 12b), small edges 12c, and large edges. A portion 12d is formed. The split mold 5 and the core 12 are set at locations where the distance from the surface is almost the same from any location. This mold structure is simpler than a conventional mold device using the core 12, and the cost is lower.

When the molten synthetic resin is injected into the split mold 5 in which the core 12 is installed by the injection nozzle 10, the boot 1 is formed with a predetermined thickness in accordance with the determined interval of the mold 5. Will be finished uniformly at any point. The boot 1 having a large thickness can be formed by reducing the shape of the core 12, and the thickness dimension can be selected according to the size of the core 12. As a result, the number of applicable materials increases, and the cost can be reduced.

As shown in FIG. 2, when the boot is discharged, the injection nozzle 10 is retracted and the split molds 5 are separated from each other, so that the ridges 7 and the valley grooves 8 of the boot 1 are connected to the core 12.
And the core 12 is housed in the boot 1 (see FIG. 3). Therefore, as shown in FIG. 4, at the time of removal from the mold, the small edge portion 2 of the boot 1 is grasped by hand, and the spiral groove is turned toward the spiral center (arrow b).
The boot 1 is rotated. At this time, since the core 12 is fixed and the boot shape is substantially conical, a gap is suddenly generated between the boot 1 and the core 12 by rotating the core 12 so that the valley groove 8 of the boot 1 is The boot 1 can be removed from the core 12 without making strong contact with the ridge 12a of the child 12, and permanent deformation can be prevented.

As shown in FIG. 5, when the mold is removed, the axis of the chuck 13 operated by the pressure of the air compressor is aligned with the axis of the boot 1, the small opening 2 is gripped by the chuck 13, and the chuck 13 is rotated. Thus, the boot 1 may be rotated and separated from the core 12. In the solidified state, excessive contact between the boot 1 and the core 12 at the time of demolding is avoided, so that the solidification time can be reduced,
Since the demolding operation is simple, the molding time can be reduced.

As shown in FIGS. 6 and 7, the boot 1 as a product has a spiral bellows on a substantially conical wall surface, and forms a small mouth portion 2 and a large mouth portion 3. When covering the floor-type shift lever, since the large mouth portion 3 is on the insertion side, the mounting is easy, and even if the shift lever is operated by the spiral bellows, the boot 1 can easily follow.

[0019]

The present invention is constructed as described above. When the boot is covered with a protruding actuator such as a shift lever or the like, the large opening is on the insertion side, so that the mounting is easy and the spiral winding is possible. Since the bellows allow easy boot deformation, the shift lever operation is smooth. Further, since the position and the interval between the split mold and the core are determined, the thickness of the boot can be made uniform, and the thickness dimension can be selected according to the size of the core. In addition, the solidified boot can be rotated to remove the boot from the core so as to avoid contact with the core, and permanent deformation can be prevented. In addition, since the boot can be prevented from being deformed, it is possible to secure stable and high quality and to reduce the defective rate even in injection molding. Further, the solidification time can be reduced, and the demolding operation is simple, so that the molding time can be shortened and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of an injection molding apparatus according to an embodiment of the present invention.

FIG. 2 is a development view of a main part of the injection molding apparatus shown in FIG.

FIG. 3 is a sectional view of the boot discharged from the mold shown in FIG. 1;

FIG. 4 is an explanatory view showing how to remove a core in the boot shown in FIG. 3;

FIG. 5 is an explanatory view showing how to remove a core inside the boot shown in FIG. 3 by a motor or the like.

FIG. 6 is a perspective view of the commercialized boot shown in FIG. 3;

FIG. 7 is a sectional view of the boot shown in FIG. 6;

FIG. 8 is a side view of a conventional boot.

FIG. 9 is an explanatory diagram of a conventional boot manufacturing by blow molding.

FIG. 10 is an enlarged view of details of FIG. 9 (c).

[Explanation of symbols]

 7 Yamajo 8 Valley groove 2 Small section 3 Large section 1 Boots 12a Mountain section 12b Valley groove 12c Small section 12d Large section 12 Core 5 Split mold

Claims (3)

[Claims] 1. A spiral shape in which spiral ridges and valleys are formed on a peripheral wall of a cylindrical body having a substantially trapezoidal cross section, and a distal end of the cylindrical body has a small opening and a base end has a large opening. Boots characterized by forming bellows. 2. A spiral flute and a valley groove are formed on a peripheral wall of a substantially truncated cone, and a tip end of the truncated cone is a fore edge,
A molten synthetic resin is injected and solidified between a core having a base end as a large opening and a split mold arranged with a substantially equally spaced gap on the surface of the core. Boot molding method. 3. When the boot formed into a spiral bellows is discharged together with the core by the molten synthetic resin injected between the core and the mold, the boot is gripped at the fore-edge portion of the boot and the boot is formed. A method of removing boots, comprising fixing an inner core and rotating the fore edge toward the center of the spiral.