JP3755660B2 - Plate blow molded body with a built-in hidden rib - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a double-walled plate-like blow molded article with a hidden rib.
[0002]
[Prior art]
In the case of producing a double-walled plate-like product with a blow molded product, in order to increase its rigidity, for example, both concave ribs or hidden ribs described in JP-A-6-179236 and JP-A-6-71738 are used. Connecting the walls. When the plate-like product requires a high appearance on the surface, such as an automobile spoiler, and a corresponding appearance is also required on the back surface, the recessed rib is not used and the hidden rib is extended from the back wall to the surface wall. The front end is welded to the inside of the surface wall.
[0003]
3 (a) and 3 (b) show this. In the double-walled plate-like blow-molded body 1, the hidden rib 4 extends from the back wall 2 toward the surface wall 3, and the front end thereof is the surface wall 3. Welded inside. In FIG. 3A, 5 and 6 are molds, 7 is a plate-like slide mold for forming the hidden rib 4 (the phantom line is a state when the slide mold 7 is projected into the cavity) ).
Thus, when the hidden rib 4 is formed only from the back wall 2 side, the parison meat is taken by the hidden rib 4 in the vicinity of the hidden rib 4 and the thickness of the back wall 2 is reduced (air blowing). With this, the back wall is stretched and thinned). Therefore, the cooling of the back wall 2 is fast and the cooling of the surface wall 3 is delayed, and the shrinkage rate accompanying the cooling increases correspondingly on the side of the surface wall 3, and as shown in FIG. Warpage occurs with a concave side.
In particular, when the surface side 3 is upholstered (see, for example, Japanese Patent Publication No. 4-53696), the cooling is further delayed on the surface side 3 and the shrinkage rate increases.
[0004]
[Problems to be solved by the invention]
In order to prevent this, the mold wall temperature is generally raised to reduce the cooling rate, or the temperature of the mold 6 on the surface wall 3 side is made higher than the temperature of the mold 5 on the back wall 2 side to increase the surface wall 3. And the method of adjusting the cooling rate of the back wall 2 and balancing shrinkage,
In any case, there is a disadvantage that the cooling time becomes long.
The present invention has been made to solve this problem, and in the case of forming the hidden rib 4 only from one wall portion in a double-walled plate-like blow molded article, the cooling time is not lengthened. The purpose is to prevent warping.
[0005]
[Means for Solving the Problems]
In the present invention, a plate-like hidden rib that connects a wall portion facing one wall portion extends from one wall portion toward the opposing wall portion, and its front end is located inside the facing wall portion. in the plate-shaped blow molded article of the welded double wall structure, the plate-like hidden ribs, the front end for a predetermined length welded to the inside of the opposite wall portion, the front end at both end portions in the longitudinal direction of their A portion inclined away from the inside of the opposing wall portion and extending in the length direction to the one wall portion is formed , and the width of the inclined portion in the length direction is w, and the hidden rib in the portion when is the hidden rib height, assuming that welded to the inside of the opposed walls has a h _1, characterized in that it is a w ≧ h _1/3.
[0006]
Further, in the present invention, the plate-like hidden rib that connects the wall portion facing one wall portion extends from the one wall portion toward the opposing wall portion, and the front end of the facing wall portion is In the plate-like blow molded article having a double wall structure welded to the inside, the plate-like hidden rib has the front end opposed to the portion where the front end is welded to the inside of the opposed wall portion over a predetermined length. It is formed portion which forms an arcuate away from the inner wall portion, and further the height of the hidden rib at the center of the portion that forms the arc as h _2, hidden ribs in the region is welded to the inside of the opposed walls when hidden rib height on the assumption was h _3, characterized in that it is a h ₂ ≦ 2h _3/3.
Also in this plate-like blow-molded body, on both end portions in the length direction of the hidden rib, the front end is separated from the inside of the facing wall portion and is inclined to the one wall portion so as to widen toward the end. is, as a specific embodiment, that has a w ≧ h _1/3 desirable.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with reference to FIG.1 and FIG.2, the plate-shaped blow molded object which concerns on this invention is demonstrated concretely.
In FIGS. 1A to 1C, reference numeral 11 denotes a double-walled plate-like blow molded body. A hidden rib 14 extends from the back wall 12 toward the surface wall 13, and its front end is located inside the surface wall 13. Welding. The hidden rib 14 is inclined so that the front end 14 s is away from the inside of the front wall 13 at both ends A and A in the lengthwise direction and extends to the rear wall 12 in the lengthwise direction. A plurality of such hidden ribs 14 are arranged on the blow molded body 11 in parallel with each other.
In FIG. 1 (a), both molds are not shown, but are the same as in FIG. 3, and the slide mold 17 (virtual line) shown in a state of protruding into the cavity is also the slide mold of FIG. There is essentially no difference from 7.
[0008]
The height of the hidden rib 14 when it is assumed that the width in the longitudinal direction at both ends A, A of the hidden rib 14 is w and the hidden rib 14 is welded to the inside of the surface wall 13 at both ends A, A ( when the inner distance) of the inner and the back wall 12 of the surface wall 13 was set to h _1, the relationship of w ≧ h _1/3 is established.
As shown in FIGS. 1A and 1B, the parison meat is taken by the hidden rib 14 at the location B where the front end of the hidden rib 14 is welded to the inside of the surface wall. Although the thickness is thin, at both ends A and A, the parison meat is not excessively removed by the rib 14, and the thickness of the back wall 12 remains relatively thick.
[0009]
In addition, conventionally, when manufacturing the blow molded object 1 shown in FIG. 3, the following processes are generally taken.
(1) The parison is lowered between the molds 5 and 6.
{Circle around (2)} Pre-pinch the parison, and pre-pressurize by blowing air into the parison before closing both molds 5,6.
(3) The molds 5 and 6 with the slide mold 7 protruded are closed and the parison is sandwiched between the molds 5 and 6. At this time, the portions sandwiched between the tip 7 of the slide mold and the mold 6 are pressed against each other and welded together.
(4) Air is blown into the parison 4 and the slide mold 7 is moved back to the cavity surfaces of the molds 5 and 6 with a slight time lag.
(5) After cooling, both molds 5 and 6 are opened, and the blow molded body 1 is taken out.
However, when the blow molded body 11 shown in FIG. 1 is manufactured, after the parison is pre-pinched, pre-pressurization is not performed. As a result, the hidden ribs 14 can be formed on both sides of the slide mold 17 so as to widen widely. The same applies to the production of a blow molded body 21 described later.
[0010]
In the plate-like blow molded body 11, the thickness of the back wall 12 is thicker in the vicinity of both end portions A and A than in the prior art. Also, the relatively thick hidden ribs 14 formed at both ends A, A do not contact either mold or slide mold 17 at any stage of the blow molding process, so both molds or It is not cooled directly by any of the slide molds 17 and has the slowest cooling rate among the plate-like blow molded bodies 11. With these two points, the cooling rates of the front wall 13 and the back wall 12 can be made uniform, and the warpage of the plate-like blow molded body 11 can be prevented.
The relationship of w ≧ h _1/3 is the result obtained relationship as a guide for aligning the cooling rate of the surface wall 13 and the back wall 12 can be realized by the manufacturing method. Depending on the cooling rate of the front wall 13 and the back wall 12, w ≧ h _1/2 may be further satisfied.
[0011]
2A to 2C, reference numeral 21 denotes a double-walled plate-like blow molded body. A hidden rib 24 extends from the back wall 22 toward the surface wall 23, and its front end is located inside the surface wall 23. Welding. The hidden rib 24 is inclined so that the front end 24 s is away from the inside of the surface wall 23 and extends to the back wall 22 in the length direction at both end portions A and A in the length direction. Further, an arc-shaped portion C in which the front end 24 s is separated from the inside of the surface wall 23 is formed in the middle of the hidden rib 24 in the length direction. As shown in FIG. 2 (c), in the plate-like blow molded body 21, a plurality of hidden ribs 24 are arranged in parallel to each other, and the position of the arcuate portion C is shifted in the length direction in the adjacent hidden ribs 24, 24. (So-called staggered arrangement).
In FIG. 2A, both molds are not shown, but are the same as those in FIG. 3, and a plurality of slide molds 27 (virtual lines) shown in a state of protruding into the cavity are also provided at predetermined intervals. Except for the fact that they are arranged in series, there is essentially no difference from the slide mold 7 of FIG. The arc-shaped portion C of the hidden rib 24 is formed in a hanging curtain shape so as to connect the plurality of slide molds 27.
[0012]
In this plate-shaped blow molded article 21, similarly to the plate-shaped blow molded article 11, both end portions A of the hidden ribs 24, in A, the relationship of w ≧ h _1/3 is established. The height of the hidden rib 24 when the height of the hidden rib 24 at the center of the arc-shaped portion C is h ₂ and the hidden rib 24 is welded to the inside of the surface wall 23 in the arc-shaped portion C (surface). when the inner distance) of the inner wall 23 and rear wall 22 and the _{h 3,} the relationship of _{h 2} ≦ _2h 3/3 are satisfied.
Then, as shown in FIGS. 2A and 2B, the parison meat is taken by the hidden rib 24 at the location B where the front end of the hidden rib 24 is welded to the inside of the surface wall. Although the thickness is reduced, in the arcuate portion C, the parison meat is not excessively removed by the ribs 24, and the thickness of the back wall 22 remains relatively thick. The same applies to both end portions A and A (see FIGS. 1A and 1B).
[0013]
Thus, in the plate-like blow-molded body 21, the thickness of the back wall 22 is thicker than before in the vicinity of both end portions A, A and the arc-shaped portion C. Also, the relatively thick hidden ribs 24 formed at both ends A, A and arcuate portion C do not contact either mold or slide mold 27 at any stage of the blow molding process, and therefore It is not cooled directly by either of the two molds or the slide mold 17, and the cooling speed is the slowest among the plate-like blow molded bodies 21. With these four points, the cooling rates of the front wall 23 and the back wall 22 can be made uniform, and the warpage of the plate-like blow molded body 21 can be prevented. Furthermore, since the arcuate portion C is shifted in the length direction in the adjacent hidden ribs 24, 24, the portions where the cooling rate is slow are distributed and arranged on the back wall 22 side, and uniform cooling is possible. It has become.
The relationship between h ₂ ≦ 2h _3/3 is the result obtained relationship as a guide for aligning the cooling rate of the surface wall 23 and back wall 22, can be realized by the production method described above. The cooling rate of the surface wall 23 and back wall 22, further _{h 2} ≦ _{h 3/2,} may be set to w ≧ _h 1/2.
[0014]
【The invention's effect】
According to the present invention, in the plate-like blow-molded body having a double wall structure, when the hidden rib is formed only from one wall portion, the cooling rate of the front wall and the rear wall is made uniform to prevent warpage. Can do. Further, since one or both of the molds are not heated more than necessary, the cooling time does not become longer as in the prior art.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view (a) of a blow-molded body according to the present invention, a II-II cross-sectional view and a III-III cross-sectional view (b) thereof, and a perspective view (c) of the blow-molded body.
FIG. 2 is a cross-sectional view (a) of another blow-molded product according to the present invention, its IV-IV cross-sectional view and VV cross-sectional view (b), and a perspective view (c) of the blow-molded product.
FIG. 3 is a cross-sectional view (a) of a conventional blow-molded body, a cross-sectional view thereof taken along line II (b), and a perspective view (c) of the blow-molded body.
[Explanation of symbols]
1, 11, 21 Plate-shaped blow molded body 2, 12, 22 Back wall 3, 13, 23 Front wall 4, 14, 24 Hidden rib 5, 6 Mold 7, 17, 27 Slide mold

Claims (4)

A plate-like concealed rib that connects one wall to the opposite wall extends from one wall to the opposite wall, and the front end is welded to the inside of the opposite wall. in the plate-shaped blow molded article of the wall structure, the plate-like hidden ribs, the front end for a predetermined length welded to the inside of the opposite wall portion, the front end at both end portions in the longitudinal direction of its said opposing walls A portion inclined away from the inside of the portion and extending in the longitudinal direction to the one wall portion is formed , and the width of the inclined portion in the length direction is w, and the hidden rib is the opposing wall in the portion. when hidden rib height when the the assumption that welded to the inside and the h _1, a built-in hidden ribs, which is a w ≧ h _1/3 plate blow molded article. A plate-like concealed rib that connects one wall to the opposite wall extends from one wall to the opposite wall, and the front end is welded to the inside of the opposite wall. In the plate-like blow molded article having a wall structure, the plate-like hidden rib is separated from the inside of the opposing wall portion between the locations where the front end is welded to the inside of the opposing wall portion over a predetermined length. portions forming the arc shape is formed Te, further the height of the hidden rib at the center of the portion that forms the arc as h _2, hidden ribs, assuming that the hidden ribs in the region is welded to the inside of the opposed walls when the height was h _3, plate-shaped blow molded article with a built-in hidden ribs, characterized in that the h ₂ ≦ 2h _3/3. The plate-like hidden rib is formed with a portion where the front end is separated from the inside of the opposing wall portion at both ends in the length direction, and is inclined to the one wall portion so as to widen toward the end. The height in the length direction of the inclined portion is w, and the height of the hidden rib is h when it is assumed that the hidden rib is welded to the inside of the facing wall at the portion. ₁ Where w ≧ h ₁ The plate-like blow-molded article according to claim 2, wherein a hidden rib is incorporated. 4. The hidden rib according to claim 2 , wherein a plurality of the hidden ribs are arranged in parallel, and a position of the arc-shaped portion in the adjacent hidden ribs is shifted in a length direction. 5. Built-in plate-like blow molded body.

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