JP2923673B2 - Blow molding hollow body fixing structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to hinges, pockets, and fasteners for blow molding a thermoplastic synthetic resin such as various panels, containers, ducts, and tanks. And a structure for fixing other members such as a mounting member.

2. Description of the Related Art Generally, in the case of a panel forming a housing of an electric device such as a computer, a copying machine, a private branch exchange, or a blow-molded hollow body such as a container, a duct, and a tank, a hinge, a pocket, and a lock are provided on the wall surface. Various other members such as a stopper and a mounting member are mounted, and a required number of nuts are embedded in the wall surface for mounting.

Conventionally, in this type of blow-molded hollow body, a nut for mounting other members is set in a mold in advance, and is embedded in the wall surface of the hollow body panel during blow molding.

[Problems to be Solved by the Invention] However, when the nut is set in the mold in advance and is buried in the hollow body, it takes time to set the nut in the mold, and the insert is required. There is a drawback that the molding cycle is lengthened because the cooling cycle of the parison in the mold is delayed by the nut. In addition, the nut set in the mold is liable to cause misalignment at the time of setting and contact with the parison, and furthermore, the eccentricity when the hollow body is separated from the mold after blow molding, and the resin after molding. There is a disadvantage that dimensional accuracy is reduced due to molding shrinkage. Further, even when molding failure occurs, there is a problem that it is difficult to regenerate the material by pulverization because the foreign material (metal) nut is embedded in the hollow body which is a molded product.

Therefore, the present inventor has developed means for forming only a nut embedding hole on the wall surface during blow molding of a hollow body, and pressing and embedding the nut in the nut embedding hole after molding. We succeeded in resolving the drawbacks and problems of the means to be buried.

However, as a result of various experiments in which a nut burying hole was formed during blow molding of a hollow body and a nut was buried and buried in the formed nut burying hole, the following problems newly occurred.

(1) If a nut embedding hole is formed together with the wall of the hollow body during blow molding of the hollow body, the nut embedding hole is formed so as to form a recess from the wall of the hollow body. As shown in FIG. Since the blow ratio of the peripheral edge b of the buried hole a becomes high, the thickness of that portion becomes thin,
It has been found that this causes the torque strength in the rotation direction and the strength in the pull-out direction of the embedded nut to be significantly reduced.

(2) As shown in the figure, when the heated nut is pushed into the nut burying hole and buried, a molten burr c which rises to the surface side at the boundary between the nut and the nut burying hole is generated. It has also been found that this causes a reduction in the mounting accuracy of the member.

(3) Furthermore, when the nut is buried, the posture of the nut immediately before burying is unstable, so it is difficult to bury the nut accurately with respect to the axis of the nut burying hole. A problem arose.

(4) Also, when the blow-molded hollow body is separated from the mold, the molded nut burying hole is in a state of firmly adhering to the mold due to molding shrinkage and the like. It was also found that the nut embedding hole was eccentric or deformed by the stress when it was separated from the mold.

In view of the above-described situation, the present invention reduces the dimensional accuracy by shortening the blow molding cycle of the hollow body and eliminating the displacement of the nut to be buried by molding only the nut embedding hole during the blow molding of the hollow body. Even in the improved one, the hole diameter of the opening is larger than the outer diameter of the tip of the nut, the hole diameter of the bottom is smaller than the maximum outer diameter of the nut, and In addition to forming the nut in an inclined shape over the portion and forming a concave portion at the opening edge of the nut embedding hole, the thickness of the opening edge of the nut embedding hole is prevented from becoming thin, and the rotational torque and torque of the embedded nut are reduced. Improves the strength in the pull-out direction, and even if molten burrs occur in the opening of the nut burial hole when burying the nut,
To provide a blow-molded hollow body fixing structure capable of preventing the swelling of the nut from the wall surface, improving the mounting accuracy of other members, and easily embedding the nut and accurately embedding the nut. It is intended for.

[Means for Solving the Problems] The present invention is configured as follows as technical means for achieving the above object. That is, in a structure in which a nut is buried in the wall surface of the blow-molded hollow body, a bolt is screwed into the nut and other members are fixed, and a nut burying hole formed during blow molding of the hollow body is provided. Nut burying hole, the hole diameter of the opening is larger than the outer diameter of the tip of the nut, and the hole diameter of the bottom is smaller than the maximum outer diameter of the nut, and further formed in an inclined manner from the opening to the tip, A blow-molded hollow body fixing structure characterized by forming a concave portion at the opening edge of the nut embedding hole.

According to the blow-molded hollow body fixing structure according to the present invention, when the hollow body is blow-molded, the hole diameter of the opening of the nut embedding hole is larger than the outer diameter of the nut tip and the hole diameter of the bottom is smaller. It is smaller than the maximum outer diameter of the nut, and it is formed in an inclined shape from the opening to the tip, and a recess is formed at the opening edge of the nut burying hole, so the blow ratio of the opening rim portion of the nut burying hole is By forming the concave portion, it is suppressed that the height is partially increased, the portion does not become thin,
It is formed into a substantially uniform thickness.

In addition, since a recess is formed at the opening edge of the molded nut burying hole, even when molten burrs occur when burying the nut,
It is housed in the recess and does not rise above the wall. For this reason, the mounting accuracy of other members does not decrease.

Furthermore, since the hole diameter of the opening of the nut embedding hole is larger than the outer diameter of the tip of the nut and the hole diameter of the bottom is smaller than the maximum outer diameter of the nut, the nut is opened immediately before embedding the nut. The setting can be performed in a stable posture, and the embedding work of the nut is improved.

Also, since the nut embedding hole is formed in an inclined shape from the opening to the tip end, even if the molded nut embedding hole is firmly adhered to the mold due to molding shrinkage or the like, the mold is not deformed. When the hollow body is separated from the nut, excessive stress does not act on the nut embedding hole, and the nut embedding hole with high dimensional accuracy is formed. Therefore, the nut is correctly embedded in the nut embedding hole.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

1 to 3 exemplify a housing 1 of an electric device, and a door panel 1a constituting a front surface of the housing 1 is constituted by a housing panel according to the present invention. On the back surface of the hollow body 2 constituting the housing panel, a pocket 3, a hinge 4 and a magnet attraction plate 5 are mounted. These are mounted on a large number of nuts 6 embedded in the wall surface of the hollow body 2 with a large number of bolts 7. It is fixed.

FIGS. 4 to 9 show a process of blow-molding the hollow body 2, embedding a nut 6 in a wall surface of the blow-molded hollow body 2, and mounting other members.

In FIG. 4, reference numerals 8 and 8 denote a pair of dies, and a plurality of pins 10 forming nut burial holes protrude from a convex cavity 9 of one of the dies 8. Reference numeral 11 denotes a concave cavity of the other mold 8. Numeral 12 denotes a parison made of a thermoplastic synthetic resin, which is arranged between a pair of open dies 8, 8 during blow molding, as shown in the figure. Then, the pair of dies 8, 8 is closed, and a pressurized fluid is pressed into the parison 12, whereby the hollow body 2 is blow-molded.

FIGS. 5 and 6 show an embodiment in which a nut embedding hole 13 is formed in the wall surface of the hollow body 2 in the process of blow molding. The pin 10 for forming the nut burial hole 13 is
The convex cavity 9 has a step 14 on the side thereof,
The nut embedding hole 13 is formed such that the hole diameter of the opening is larger than the outer diameter of the tip of the nut 6, the hole diameter of the bottom is smaller than the maximum outer diameter of the nut 6, and the hole is inclined from the opening to the tip. It has a shape that is slightly tapered and inclined so as to be formed into a shape. The inclination angle is 1 to 7 degrees.

As shown in FIG. 5, when the pair of dies 8, 8 is closed and a pressurized fluid is blown into the Paris 12, the Paris 12 gradually expands, and as shown in FIG. The hollow body 2 having a shape along the 8, 8 convex cavities 9 and the concave cavities 11 is formed, and a nut embedding hole 13 along the shape of the pin 10 is formed on the wall surface of the hollow body 2 during this forming process. You. A recess 15 is formed at the opening edge of the nut embedding hole 13 by the step portion 14. The pin 10 is slidable,
In the state shown in FIG. 6, the hollow body 2 may be taken out of the dies 8, 8 after the pin 10 is first retracted and pulled out from the nut embedding hole 13.

Then, when the blow molding step of the hollow body 2 is completed by the pair of dies 8, 8, the pair of dies 8, 8 is cooled, opened, and the hollow body 2 is taken out, as shown in FIG. The nut 6 is set in the opening of the nut burying hole 13 so as to be perpendicular to the mural, and the nut 6 is pressed using a nut pushing machine.
Is heated and buried. Numeral 16 denotes a nut loading section of the nut pushing machine, which has heating means inside.

By the way, since the hole diameter of the opening is larger than the outer diameter of the tip of the nut 6 and the hole diameter of the bottom is smaller than the maximum outer diameter of the nut 6 as described above, Immediately before embedding, the nut 6 can be set in the opening of the nut embedding hole 13 in a stable posture, and the workability of embedding the nut 6 is improved. Also, the nut burial hole 13 is
As the hollow body 2 is separated from the dies 8, 8, no excessive stress acts on the nut embedding hole 13 because the nut is formed in an inclined shape from the opening to the tip end, so that the nut embedding hole 13 with high dimensional accuracy is formed. Is done. Therefore, as described above, the nut 6 is correctly embedded in the nut embedding hole 13. In the case where the pin 10 is slidable, the pin 10 can be retracted and the pin 10 can be pulled out from the nut burial hole 13 in advance as described above, so that the eccentricity and deformation of the nut burial hole 13 can be further ensured. Can be prevented. Note that the inclination of the nut burying hole 13 does not necessarily have to be a uniform angle from the opening to the tip end direction. For example, the inclination angle near the opening may be set to zero and a paragraph may be provided. .

Furthermore, since the nut 6 is buried after the hollow body 2 is blow-molded, the nut 6 is buried with high precision without causing the position shift and the eccentricity which occur when the nut 6 is set and buried during the blow molding. You. And
Since the concave portion 15 is formed by the step portion 14 at the opening edge of the nut burying hole 13, the blow ratio of the opening of the nut burying hole 13 does not become partially high. The reduction in the torque in the rotational direction and the strength in the pulling direction of the embedded nut 6 due to the thinning is prevented. In addition, since the formed burial hole 13 has a concave portion 15 at the opening edge thereof, even if a molten burr is generated when the nut 6 is buried, it is contained in the concave portion 15 and does not rise from the wall surface. For this reason, the mounting accuracy of other members does not decrease. Thus, the recess 15 is provided with the nut burying hole.
This is for preventing the opening of the thirteen from becoming thin and preventing the burrs from rising from the wall surface of the molten burr generated when the nut 6 is buried. On the other hand, the opening diameter of the concave portion 15 is preferably about 1.2 to 3.0 times the hole diameter of the nut burying hole 13, and the depth of the concave portion 15 is It is preferably about 0.1 to 0.5 times the depth. The shape of the concave portion 15 is usually formed in a circular shape so as to surround the periphery of the nut embedding hole 13, but this is not necessarily required to be circular.For example, a radial groove is further formed in the circular concave portion. Multiple sections may be formed.

Further, at the time of blow molding, only the nut burying hole 13 in which the nut 6 is not inserted into the hollow body 2 is formed. Therefore, when molding failure occurs, it is easy to crush the molding failure and regenerate the material. is there.

FIG. 9 shows an embodiment in which the nut 6 is embedded in the nut embedding hole 13 of the blow-molded hollow body 2 and the pocket 3 is mounted.

The hollow body 2 is made of a hard thermoplastic resin such as ABS resin, modified polyphenylene oxide, polyamide, or polypropylene, which is suitable for blow molding.

According to the structure for fixing a blow-molded hollow body according to the present invention, in a structure in which a nut is embedded in a wall surface of the blow-molded hollow body, and a bolt is screwed into the nut to fix another member. Has a nut buried hole formed at the time of blow molding the hollow body, the hole of the nut is larger than the outer diameter of the tip of the nut, and the hole diameter of the bottom is larger than the maximum outer diameter of the nut. It is small and has an inclined shape from the opening to the tip, and a recess is formed at the opening edge of the nut burial hole, so that the thickness of the opening rim of the nut burial hole is reduced. To improve the torque in the rotating direction and the strength in the pull-out direction of the buried nut, and to prevent the burrs from rising from the wall surface even if molten burrs occur in the opening of the burial hole when burying the nut. , Other parts After which it is possible to improve the mounting accuracy, further, burying operation of the nut is easily and accurately effect of embedding the nut is obtained.

[Brief description of the drawings]

1 to 3 show an example of a housing of an electric device provided with a housing panel according to the present invention as a door panel. FIG. 1 is an overall perspective view, and FIG. 2 is a perspective view of the door panel viewed from the back. , FIG. 3 is an exploded perspective view of the same, and FIG.
FIG. 6 to FIG. 6 show the blow molding of the hollow body.
FIG. 5 is a plan view showing a mode before blow molding, FIG. 5 is a partial cross-sectional view showing a mode at the start of blow molding, FIG. 6 is a partial cross-sectional view showing a mode at the end of blow molding, The figure is a partial side view showing a mode in which a nut is pushed and buried in a blow-molded hollow body, FIG. 8 is a cross-sectional view of a part of the hollow body after the nut is buried, and FIG. FIG. 10 is a partial cross-sectional view showing a mode in which the member is mounted, and FIG. 10 is a partial cross-sectional view of a hollow body for explaining the problem of the present invention. 1 ... Housing of electric device, 1a ... Door panel, 2 ...
... hollow body, 3 ... pocket, 4 ... hinge, 6 ... nut, 7 ... bolt, 8,8 ... a pair of molds, 9 ... ... convex cavity, 10 ... pin, 11 ... concave Cavity, 12 ……
Parison, 13 ... Nut buried hole, 14 ... Step, 15 ... Recess

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 65/56-65/64 B29C 49 / 20,49 / 42

Claims (1)

(57) [Claims] 1. A structure in which a nut is buried in a wall surface of a blow-molded hollow body, and a bolt is screwed into the nut to fix another member. The hole where the opening is larger than the outer diameter of the tip of the nut, and the hole diameter at the bottom is smaller than the maximum outer diameter of the nut, and the nut is slopingly formed from the opening to the tip. A blow molding hollow body fixing structure, wherein a concave portion is formed at an opening edge of the nut burying hole.