JP2024061177A - Vacuum forming equipment - Google Patents

Abstract

[Problem] To suppress the occurrence of wrinkles in a resin sheet while maintaining the tension of the resin sheet. [Solution] A resin sheet is provided with a reference portion 11 having a reference surface, a flange portion 12 arranged inside the reference portion 11 and having ridges 21, 22 formed on the upper surface, and a product portion 13 arranged inside the flange portion 12 and having walls 13b, 13c, and the ridges 21, 22 provided on the flange portion 12 are rectangular in top view and at least one of the following is true: the long side direction is formed along the wall surfaces of the walls 13b, 13c, and the ridges 21, 22 have an inclination such that the height with respect to the reference surface is different between one end 21a and the other end 21b in the long side direction. [Selected Figure] Figure 1

Description

This disclosure relates to a vacuum forming device for products.

A method for forming resin molded products is to remove the product from the mold and vacuum mold it. The vacuum molding method disclosed in Patent Document 1 is a technology for integrating the resin and the insert, so it cannot be applied to products that do not integrate the resin and the insert. Furthermore, wrinkles may occur in the insert part and the wall part of the mold.

There are two types of wrinkles: webs, which occur when a male mold is used during vacuum forming, and bridges, which occur when a female mold is used. If no ridges are placed near the molded product, webs will occur at the corners of the product, but by providing a peripheral wall around the molded product and placing ridges, the occurrence of webs can be suppressed.

JP 2013-078915 A

However, the vacuum molding method disclosed in Patent Document 1 has the problem that it is not possible to prevent wrinkles in the resin sheet when the molded product is box-shaped, especially when the corners have complex shapes.

For example, simply providing a peripheral wall around the molded product may not be sufficient to prevent wrinkles. Specifically, if the ridges are not properly positioned, bridges may occur between the long sides of the ridges and the vertical wall of the product, i.e., as wrinkles on the back of the ridges. This makes it difficult to prevent the occurrence of both webs and bridges; in other words, it is difficult to prevent the resin sheet from sagging and to prevent the occurrence of new wrinkles between the block and the product.

The present disclosure provides a vacuum forming device that suppresses the occurrence of wrinkles in a resin sheet while maintaining the tension of the resin sheet.

The vacuum molding apparatus of the present disclosure comprises a reference portion having a reference surface, a flange portion arranged inside the reference portion and having a ridge portion formed on its upper surface, and a product portion arranged inside the flange portion and having a wall portion, wherein the ridge portion provided on the flange portion is rectangular in top view and is at least one of: the ridge portion is formed with its long side direction aligned with the wall surface of the wall portion; and the height based on the reference surface is inclined so that it is different between one end and the other end in the long side direction.
This makes it possible to stretch the corners of the resin sheet while suppressing the occurrence of wrinkles caused by the ridges themselves.

This disclosure provides a vacuum forming device that can suppress the occurrence of wrinkles in a resin sheet while maintaining the tension of the resin sheet.

FIG. FIG. FIG. 2 is a top view of the vacuum forming apparatus. 1A to 1C are diagrams showing an example of a procedure for attaching a resin sheet to a vacuum forming device by vacuum drawing.

First embodiment
Hereinafter, a vacuum forming apparatus according to the present embodiment will be described with reference to the drawings. Fig. 1 is a perspective view showing a part of a vacuum forming apparatus 1. The vacuum forming apparatus 1 includes a reference portion 11, a flange portion 12 provided on the reference portion 11, and a product portion 13 provided on the flange portion 12.

When vacuum molding non-reinforced thermoplastic resin, the reference portion 11 and the flange portion 12 are the portions that are on the outside of the product portion of the molded product when the product shape is box-shaped, and are trimmed after molding and do not become part of the product.

The reference part 11 is a generally rectangular parallelepiped that is thin in the vertical direction. For example, the reference part 11 is placed on a horizontal base. In addition, the upper side of the reference part 11 has a flat reference part upper surface 11a that extends horizontally and has the vertical direction as its normal direction.

In the following description, the vertical direction, which is the normal direction of the reference part upper surface 11a, is defined as the Z direction, and the directions perpendicular to the Z direction and perpendicular to each other are defined as the X direction and the Y direction. The X direction is defined as the left-right direction, and the Y direction is defined as the front-rear direction. The reference part 11, which is approximately rectangular, is described as having reference part left-right surfaces 11b formed on the X direction side, and reference part front-rear surfaces 11c formed on the Y direction side.

Furthermore, in the following description, the direction in which the product portion 13 is provided may be referred to as the inside, and the outer edge side of the reference portion 11 may be referred to as the outside.

Figure 2 is a view from the A direction in Figure 1, with the reference part front and rear surfaces 11c of the reference part 11 of the vacuum forming device 1 facing forward. As shown in Figures 1 and 2, the flange part 12 is formed on the reference part upper surface 11a of the reference part 11, and is formed with a predetermined thickness so as to protrude upward from the reference part upper surface 11a.

Figure 3 is a top view showing the flange portion upper surface 12a of the flange portion 12 near a corner of the product portion 13 described below. In addition, when viewed from above, the outer diameter portion of the flange portion 12 near the corner 13a of the product portion 13 described below is formed in a substantially circular shape.

As shown in FIG. 2, the flange portion 12 is formed so that the thickness of the flange portion protruding upward from the reference portion upper surface 11a of the reference portion 11 varies. In other words, the flange portion upper surface 12a is inclined at a predetermined angle with respect to the horizontal reference portion upper surface 11a. As an example, FIG. 1 and FIG. 2 show a state in which the thickness of the flange portion 12 is thinner toward the front side in the Y direction and thicker toward the rear side.

The upper side of the flange portion 12 has a flange portion upper surface 12a. In addition, the flange portion upper surface 12a has a number of ridges that protrude upward from the surface. Here, two ridges are formed on the flange portion upper surface 12a, which are referred to as a first ridge portion 21 and a second ridge portion 22. The first ridge portion 21 and the second ridge portion 22 will be described later.

As shown in FIG. 3, the product portion 13 is formed on the inside of the flange portion 12, on the flange portion upper surface 12a, protruding upward. Here, the product portion 13 is a mold formed into the product shape. For example, the product portion 13 is approximately a rectangular parallelepiped measuring about 300 mm in the X direction, 1000 mm in the Y direction, and 100 mm in the Z direction, and FIG. 3 is an enlarged view of a corner of this product portion.

As shown in FIG. 3, when viewed from above, the product portion 13 has a corner portion 13a at a corner in the XY direction. Furthermore, the product portion 13 has a first wall portion 13b and a second wall portion 13c that sandwich this corner portion 13a. Here, the first wall portion 13b and the second wall portion 13c each have a predetermined height. Furthermore, the first wall portion 13b extends approximately in the X direction, and the second wall portion 13c extends approximately in the Y direction.

Note that here, when viewed from above, the corner 13a is formed at an acute angle. As a result, the angle between the first wall 13b and the second wall 13c, i.e., the angle between the extension line along the first wall 13b and the extension line along the second wall 13c, is also an acute angle that is less than 90°.

The width from the outer periphery of the product portion 13 to the outer edge of the flange portion upper surface 12a, i.e., the width of the flange portion upper surface 12a, is approximately 50 mm. In other words, in the normal direction of the first wall portion 13b of the product portion 13, the distance from the first wall portion 13b to the outer edge of the flange portion upper surface 12a is approximately 50 mm, and in the normal direction of the second wall portion 13c, the distance from the second wall portion 13c to the outer edge of the flange portion upper surface 12a is also approximately 50 mm. Note that the width of this flange portion 12 can be changed as desired.

3, the first peak 21 and the second peak 22 are formed at a predetermined position on the flange upper surface 12a. As an example of this predetermined position, the first peak 21 is disposed at a predetermined distance outward from the first wall 13b, more specifically, in the flange 12, it is disposed slightly outward from the center in the inward-outward direction. Furthermore, as described in detail later, the first peak 21 is disposed at a position where the corner 13a is disposed on the normal line of the long side of the first peak 21 when the long side direction of the first peak 21 is parallel to the first wall 13b. Here, the first peak 21 is disposed between the outer periphery of the flange 12 and the corner 13a of the product 13, and is disposed at a position where it hits the peak before the corner 13a of the product 13 when the resin sheet 31 becomes soft.

Similarly, the second peak 22 is disposed at a predetermined distance outward from the second wall 13c, and more specifically, is disposed slightly outward from the center in the inward-outward direction in the flange 12. Furthermore, as described in detail later, the second peak 22 is disposed at a position where the corner 13a is disposed on the normal line of the long side of the second peak 22 when the long side direction of the second peak 22 is parallel to the second wall 13c. Here, the second peak 22 is disposed between the outer periphery of the flange 12 and the corner 13a of the product 13, and is disposed at a position where it hits the peak before the corner 13a of the product 13 when the resin sheet 31 becomes soft. Note that the positions where the first peak 21 and the second peak 22 are formed are not limited to these positions, and can be any position in the vicinity of the corner 13a.

Here, the shape of the first peak 21 and the second peak 22 will be described in more detail. The first peak 21 and the second peak 22 are rectangular in top view and have long and short sides in a predetermined direction. Here, the long sides of the first peak 21 and the second peak 22 are each about 30 mm, and the short sides are about 15 mm.

In top view, the long side direction of the first peak portion 21 is arranged so as to follow the wall surface of the first wall portion 13b. That is, the long side direction of the first peak portion 21 is arranged so as to follow the first reference line based on the wall surface of the first wall portion 13b, and is approximately parallel. The degree of parallelism between the long side direction of the first peak portion 21 and the wall surface of the first wall portion 13b is within a tilt of about ±10°. In FIG. 3, the long side direction of the first peak portion 21 is illustrated as being parallel to the wall surface of the first wall portion 13b, and the long side direction in this parallel state, where the tilt is 0°, and as another example, the long side direction in the case where the tilt is +10° from the parallel state, are each shown by a dashed line.

Similarly, the long side direction of the second peak portion 22 is arranged approximately parallel to a second reference line based on the wall surface of the second wall portion 13c. The degree of parallelism between the long side of the second peak portion 22 and the wall surface of the second wall portion 13c is approximately plus or minus 10°.

As shown in FIG. 3, the vacuum forming device 1 can set a conceptual line (outer edge line) of the outer edge of the resin sheet, which is formed by gently connecting the midpoint between the wall of the product portion 13 and the outer edge of the flange portion upper surface 12a. The outer edge of the resin sheet is the position of the base where the resin sheet 31 and the flange portion upper surface 12a are in close contact with each other moves inward and finally reaches the product portion during the time process in which the resin sheet 31 becomes accustomed to the product portion 13 inside the flange portion 12. If there is a first peak portion 21 or a second peak portion 22, the outer edge of the resin sheet comes into contact with the peaks and then passes over the peaks to reach the product portion 13.

In the following, the inside and outside directions of the outer edge of the resin sheet and the inside and outside directions of the arrangement of the reference portion 11, flange portion 12, and product portion 13 are simply described as inside and outside, assuming that they are the same direction.

As shown in FIG. 3, the first peak 21 has one end 21a in the long side direction disposed closer to the inside, and the other end 21b disposed closer to the outside than the one end 21a. In other words, the other end 21b is disposed closer to the outer edge of the flange portion upper surface 12a in the extension direction of the long side direction than the one end 21a.

Here, the height of the first peak 21 in the Z direction is about 20 mm protruding from the flange surface. In addition, a slope is provided on the upper surface so that the height of one end 21a located closer to the inside and the height of the other end 21b located on the outside of the first peak 21 are different. Specifically, the height of the upper end of the other end 21b is formed to be 1 mm or more lower than the height of the upper end of one end 21a.

The height of the first peak 21 in the Z direction is determined by the height from the reference portion top surface 11a of the reference portion 11, and also determines the difference in height between one end 21a and the other end 21b.

Similarly, the second peak 22 is formed so that the height of the other end located closer to the outside is lower than the height of one end located closer to the inside in the long side direction.

Now, with reference to Figures 4(a) to (c), an example of a molding process in which a resin sheet 31 is covered onto a product portion 13 using a vacuum molding device 1 will be described.

The resin sheet 31 may be a thermoplastic resin sheet 31. A heating device (not shown) may be used to heat the vacuum forming device 1 and the resin sheet 31. The resin sheet 31 is held by an outer frame 32.

Figure 4 (a) shows the state in which the resin sheet 31 held by the outer frame 32 has been lowered from above the vacuum forming device 1 to a predetermined position. At this time, the resin sheet 31 abuts against the edge of the upper surface of the product portion 13, the outside of the flange portion 12, and the outside of the ridges such as the outer end 21b of the first ridge portion 21.

As shown in FIG. 4(b), the vacuum forming device 1 draws a vacuum around the flange portion 12. This causes the resin sheet 31 to adhere to the surface that forms the outer periphery of the flange portion 12, i.e., to become tame. At this time, the resin sheet 31 from the product portion 13 to the outer periphery of the flange portion 12 is stretched like a tent, and in some cases, is partially in contact with the ridges 21 and 22.

Next, as shown in FIG. 4(c), the vacuum forming device 1 draws a vacuum inside the outer edge of the flange portion 12. This moves the resin sheet 31 from the taut state shown in FIG. 4(b) to a state where it is attached to the first wall portion 13b and the second wall portion 13c of the product portion 13.

Here, the long side direction of the peaks 21 and 22 is arranged along the wall portions 13b and 13c of the product portion 13. Usually, wrinkles near the peaks 21 and 22 occur at the position that connects the long side of the peak and the product wall at the shortest distance, but if the long side of the peak and the product wall are arranged parallel to each other, the shortest distance between the parallel lines is the same at any position, so there is no specific location where the long side of the peak and the product wall are at the shortest distance. In this case, for example, in the first peak 21, the wrinkles between the long side of the peak and the product wall are lowered at the location where they join around the ends 21a and 21b in the long side direction of the peak 21, that is, the wrinkles in the middle of the ends 21a and 21b. And because the wrinkles are lowered, as the outer edge line approaches the product wall, the resin sheet 31 sticks to the flange portion upper surface 12a, and separates from the product wall and the peak side, eliminating the wrinkles, and finally the resin sheet 31 adheres to the product wall and the peak.

As a result, in the vacuum forming device 1, the long side direction of the ridge portion on the upper surface 12a of the flange portion is arranged so as to follow the wall surface of the product portion 13, thereby making it possible to suppress the occurrence of wrinkles on the ridge side when performing vacuum forming using the resin sheet 31.

At this time, furthermore, in the locations where the first ridge portion 21 and the second ridge portion 22 are provided, the outer edge of the resin sheet 31 comes into contact with these ridge portions, and then passes through the ridge portions to reach the product portion 13. Here, for example, in the first ridge portion 21, by making the height of the portion where accommodating occurs first, i.e., the outer end portion 21b side, lower than the inner end portion 21a side, it is possible to lower the height of the wrinkles on the back surface of the ridge while maintaining the tension of the sheet throughout the first ridge portion 21. The same is true for the second ridge portion 22.

In other words, in the vacuum forming device 1, the height of the ridges 21, 22 on the flange upper surface 12a is lower at the outer side in the long side direction than at the inner side, thereby preventing wrinkles from occurring on the ridge side when vacuum forming is performed using the resin sheet 31.

For example, if the ridges 21, 22 are simply lowered, the sagging of the resin sheet 31 may not be suppressed completely, which may result in wrinkles. However, by arranging the long sides of the ridges 21, 22 parallel to the walls 13b, 13c of the product part 13 and tilting the upper parts of the ridges 21, 22 to create a difference in height between the inner and outer parts, the effect of suppressing wrinkles in the resin sheet 31 can be improved.

The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the invention. In other words, the above description has been omitted or simplified as appropriate for the purpose of clarity, and a person skilled in the art can easily modify, add, or convert each element of the embodiment within the scope of the present invention.

For example, in the above-mentioned description, the corner 13a of the product portion 13 is formed at an acute angle, but it does not have to be at an acute angle.

Reference Signs List 1 Vacuum forming device 11 Reference portion 11a Reference portion upper surface 11b Reference portion left and right surfaces 11c Reference portion front and rear surfaces 12 Flange portion 12a Flange portion upper surface 13 Product portion 13a Corner portion 13b First wall portion 13c Second wall portion 21 First peak portion 21a End portion 21b End portion 22 Second peak portion 31 Resin sheet 32 Outer frame

Claims (1)

A reference portion having a reference surface;
a flange portion disposed inside the reference portion and having a ridge portion formed on an upper surface thereof;
A product portion is disposed inside the flange portion and has a wall portion,
The peak portion provided on the flange portion is at least one of a rectangular shape in a top view, and a long side direction is formed along a wall surface of the wall portion, or a height based on the reference plane is inclined so that one end and the other end in the long side direction are different in height.
Vacuum forming equipment.

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