JPH1134176A - Manufacture of resin model - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately evaluate the strength by estimating the plate thickness change due to press molding and penetration into weld bead sections. SOLUTION: A manufacturing method comprises a process for manufacturing a vacuum molded product 1 formed by vacuum molding a resin plate composed of thermoplastic resin into the given shape and a process for butting another resin material 2 composed of thermoplastic resin with the vacuum molded product 1 and thermowelding a resin welding bar 3 composed of thermoplastic resin on a butting section. In that case, the reduction of plate thickness at the time of press molding an actual part can be simulated by vacuum molding a resin plate, and also penetration of a welded metal into weld bead sections at the time of welding the actual part can be simulated by using the resin welding bar 3 and carrying out the thermowelding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a resin model.

[0002]

2. Description of the Related Art In general, when manufacturing a press-welded part, for example, a resin model is manufactured before manufacturing an actual part, and a strength test using a strain gauge or the like and a FEM (Fine Element Element Method) are performed on the resin model.
d, finite element method) analysis to evaluate strength and rigidity,
If the evaluation result is good, an actual part is prototyped, and the strength and rigidity of the actual part are actually evaluated.

A resin model used in such a strength / rigidity evaluation process has conventionally been manufactured by an optical molding method. This method uses a three-dimensional CAD (Computer Aided Des) of a resin model to be manufactured.
(ign) The three-dimensional shape of the resin model is formed by sequentially laminating and curing ultraviolet curing resin layers corresponding to the horizontal cross-sectional shape of the resin model based on the data.

[0004]

However, in the above-mentioned conventional optical molding method, a resin model is formed based on three-dimensional CAD data of an actual part. There were various disadvantages shown. (1) When the press molding is performed, the thickness of the material is locally reduced, and the strength of the portion is reduced. For example, when the drawing at the time of drawing is deep, the corner R portion is thinned, and the strength of that portion is reduced. However, when stereolithography is performed based on the three-dimensional CAD data, such a change in plate thickness cannot be simulated. For this reason, it is not possible to anticipate the influence of the change in the sheet thickness in the case of press forming, and it is impossible to accurately evaluate the strength of the sheet thickness reduced portion.

[0005] (2) When welding a press-formed product, a base material is melted by welding at a weld bead portion.
The penetration shape and penetration depth affect the strength at the weld bead portion. That is, in the weld bead portion, in addition to the concentration of stress at the toe portion, the stress also concentrates at the tip portion (root portion) where the base material has melted, and fracture may occur from this root portion. However, when the optical molding is performed based on the three-dimensional CAD data, even if the molding can be performed according to the outer shape of the weld bead portion, such a penetration shape and a penetration depth cannot be simulated.
For this reason, in the resin model obtained by the conventional optical molding method, the stress concentration position in the weld bead portion is different from that of the actual part actually welded, and the strength in the weld bead portion cannot be accurately evaluated.

The present invention has been made in view of the above circumstances, and even when a resin model of a press-welded part is manufactured, it is possible to simulate a change in thickness due to press forming, a penetration shape at a weld bead portion, and the like. Accordingly, it is an object of the present invention to provide a method of manufacturing a resin model capable of accurately evaluating the strength of a reduced thickness portion and a weld bead portion.

[0007]

According to the present invention, there is provided a resin model manufacturing method for solving the above-mentioned problems, comprising: a step of vacuum-forming a resin plate made of a thermoplastic resin into a predetermined shape to obtain a vacuum-formed product; Superimposing or butting another resin material made of a thermoplastic resin on the vacuum molded product, and thermally welding a resin welding rod made of a thermoplastic resin to the overlapped portion or the butted portion. Things.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The resin model manufacturing method of the present invention can be suitably used when manufacturing a resin model of a press-welded part. Hereinafter, an embodiment in which a resin model of a press-welded part as an actual part is manufactured will be described. First, one resin plate made of a thermoplastic resin is vacuum-formed into a predetermined shape to obtain a vacuum-formed product.

The type of the thermoplastic resin of the resin plate is not particularly limited, and polyethylene, polypropylene, polystyrene, vinyl chloride resin, acrylonitrile-butadiene-styrene, ABS resin and the like can be used.
The thickness of the resin plate before vacuum forming can be appropriately set according to the thickness of the actual part.

[0010] As a vacuum forming die used for vacuum forming, a mold having a die surface corresponding to the shape of an actual part is prepared in advance. For example, a vacuum forming die can be prepared from wood, gypsum, thermosetting resin, or the like based on three-dimensional CAD data of actual parts. The vacuum forming die may be either a male type or a female type. In the vacuum forming of the resin plate, the resin plate was heated to a temperature at which the resin was thermally deformed and did not melt and was previously heat-softened. It can be performed by evacuating the inside of the mold in the state. Since the inside of the mold is decompressed, the resin plate is pressed along the mold surface by the atmospheric pressure to be formed into the shape of the mold surface.

In such vacuum forming, since the resin plate is stretched and formed into a predetermined shape, the thickness of the resin plate is reduced. It has been confirmed by the present inventor's experiments that the reduction in the thickness of the plate due to the vacuum forming and the reduction in the thickness due to the press forming are almost the same. For example,
When a real part is drawn, the corner R becomes thinner, but when the resin plate is vacuum-formed along the female mold surface into the same shape as the drawing, the corner R becomes thinner in the same manner. For this reason, by controlling the reduction in the thickness of the resin plate during vacuum forming, it is possible to simulate a change in the thickness when an actual part is press-formed. At this time, the degree of reduction in the thickness of the resin plate depends on the degree of stretching of the resin plate, and the degree of stretching can be controlled by adjusting the heating temperature of the resin plate. That is, if the heating temperature is set to be higher, the degree of stretching of the resin plate and, consequently, the degree of reduction of the plate thickness increase. Also,
By locally varying the temperature of the resin plate during vacuum forming, it is also possible to control the degree of reduction in the thickness of that portion. For example, by locally heating the resin plate during vacuum forming, the degree of reduction in the thickness of the resin plate can be increased at the locally heated portion. Furthermore, when performing vacuum molding using a male mold, by adjusting the height of the mold (the height from the clamping position of the resin plate to the top surface of the mold),
It is also possible to control the degree of reduction in the thickness of the side wall portion of the molded product.

Next, another resin material made of a thermoplastic resin is overlapped or butted on the vacuum molded product,
A resin welding rod made of a thermoplastic resin is thermally welded to the overlapping portion or the butt portion. The type of the thermoplastic resin of the other resin material is not particularly limited, polyethylene, polypropylene, polystyrene, vinyl chloride resin,
Acrylonitrile-butadiene-styrene, ABS resin and the like can be used. The resin may be the same or different from the resin used for the resin plate.

The shape of the other resin material is not particularly limited.
For example, a plate material or a square material may be used. Further, a vacuum molded product obtained by vacuum molding a plate-like thermoplastic resin may be used. As for the above-mentioned superposition, another resin material may be partially superposed on one vacuum-formed product, or a plurality of vacuum-formed products of the same shape may be entirely superposed. For the butting, a plurality of vacuum molded products may be arranged in parallel, and their side end surfaces may be opposed to each other, or the side end surfaces of another resin material may be opposed to the upper surface of one vacuum molded product. May be abutted in a T-shape.

The type of the thermoplastic resin of the resin welding rod is not particularly limited, and may be polyethylene, polypropylene, or the like.
Polystyrene, vinyl chloride resin, acrylonitrile-butadiene-styrene, ABS resin and the like can be used. The resin may be the same or different from the resin used for the resin plate. The cross-sectional shape of the resin welding rod is not particularly limited, and may be square or circular. In addition, the thickness of the resin welding rod can be appropriately set according to the outer shape of the weld bead portion in the actual part.

[0015] The thermal welding by the resin welding rod is performed by disposing the resin welding rod at the overlapping portion or the butt portion of the vacuum formed product,
It can be carried out by heating the resin welding rod and the overlapped portion at a temperature at which the resin of the resin welding rod and the resin of the resin plate are melted and these resins are not thermally decomposed. When a resin welding rod is heat-welded to the overlapping part of a vacuum formed product,
The resin welding rod and the vacuum formed product themselves melt and solidify after cooling. Thus, even in heat welding using a resin welding rod,
In the same way as welding metal melts when welding with actual parts using a welding wire, welding resin (a resin welding rod and a vacuum formed product as a base material) melts. For this reason, by controlling the penetration of the welding resin at the time of thermal welding using the resin welding rod, it is possible to simulate the penetration of the welding metal in the weld bead portion when an actual part is welded. On this occasion,
The degree of penetration of the welding resin depends on the type of resin and the heating conditions, but the type and heating conditions of the resin can be freely selected and controlled according to the penetration in the actual part.

The heating means for heat welding is not particularly limited, but it is preferable to use a hot air generator such as a dryer in terms of easiness of operation. As described above, according to the method of the present invention, by vacuum forming a resin plate, it is possible to simulate a reduction in the thickness of a real part when press forming the same, and by heat welding using a resin welding rod, It is possible to simulate penetration of a weld metal in a weld bead portion when welding an actual part. Therefore, if a strength test or the like is performed on the resin model obtained by the method of the present invention,
Accurate evaluation can be made in consideration of changes in the thickness of the plate during press forming and penetration of the weld bead.

[0017]

The present invention will be described below in detail with reference to examples. (Embodiment 1) In this embodiment, a resin model of a simple bracket as a welding press part is manufactured.

One resin plate (thickness: 3 mm) made of polyvinyl chloride as a thermoplastic resin was prepared. This resin plate was heated to 190 ° C. to be thermally softened, and vacuum-formed using a vacuum forming die (male type) having a predetermined mold surface shape, to obtain a vacuum-formed product 1. In addition, the vacuum forming die is a three-dimensional C
It was produced based on AD data. On the other hand, as another resin material, a resin plate made of polyvinyl chloride (plate thickness: 3 m
m) 2 was prepared.

An end face of the resin plate 2 was butted against the vacuum molded product 1, and a resin welding rod (thickness: 2 mm) made of polyvinyl chloride and having a circular cross section was arranged at the butted portion. Then, hot air was applied to the butted portion where the resin welding rod 3 was disposed by using a dryer 4 to heat and heat weld. The heating temperature at this time is 150 ° C. Thus, the resin model 5 of the simple bracket shown in the perspective view of FIG. 2 was manufactured.

(Evaluation of Strength Measurement) As shown in FIG. 3, a strain gauge was attached to each of the parts g1 to g9 of the resin model 5, and the strain ε when a load of 30 kg and 60 kg was applied was measured. The results for a 30 kg load are shown in FIG. 4 and the results for a 60 kg load are shown in FIG. For comparison, the distortion was measured in the same manner for the actual part as the welding press part having the same shape as the resin model 5. The results are shown in FIGS. 4 and 5.

As is clear from FIGS. 4 and 5, the strain measurement results of the actual part and the resin model 5 agree qualitatively well, and the strain measurement result of the resin model 5 is used for evaluating the strength of the actual part. It is clear that it is fully available. (Embodiment 2) This embodiment is to manufacture a resin model of a lower arm as a suspension part for an automobile, which is a welding press part.

A resin plate made of polyvinyl chloride (plate thickness:
(2.5 mm) was vacuum-formed into a predetermined shape to obtain a plurality of vacuum-formed products. The heating temperature of the resin plate at this time was 190 ° C.
The vacuum mold is manufactured based on three-dimensional CAD data of actual parts. Then, a plurality of vacuum formed products are partially overlapped, and a resin welding rod (thickness: 2 mm) having a circular cross section made of polyvinyl chloride resin is overlapped on the overlapped portion.
And heat-welded using a dryer. The heating temperature at this time is 150 ° C. Thereafter, post-processing such as punching and cutting was performed to produce a resin model 6 shown in the plan view of FIG.

(Measurement of Thickness Distribution) The thickness distribution of the resin model 6 was measured at a plurality of locations. The thickness distribution in the direction of the arrow AA in FIG. 6 is shown in FIG. 7, the thickness distribution in the direction of the arrow BB in FIG. 6 is shown in FIG. 8, and the thickness in the direction of the arrow CC in FIG. The thickness distribution is shown in FIG. For comparison, the sheet thickness distribution was similarly measured for an actual part as a welding press part having the same shape as the resin model 6. The results are also shown in FIGS.

As is apparent from FIGS. 7 to 9, it can be seen that the tendency of the thickness distribution of the real part press-molded and the resin model 6 vacuum-formed coincide with each other. (Strength Measurement Evaluation) As shown in FIG. 10, strain g was attached to each of the parts g1 to g8 for the resin model 6, and the strain ε when a load of 100 kg and 200 kg was applied was measured. The results of the 100 kg load are shown in FIG.
FIG. 12 shows the result of the 0 kg load.

For comparison, distortion was measured in the same manner for actual parts as welding press parts having the same shape as that of the resin model 6. The results are shown in FIGS. 11 and 12. As is clear from FIGS. 11 and 12, the strain measurement results of the real part and the resin model 6 are qualitatively well matched, and the strain measurement result of the resin model 6 is sufficiently used for evaluating the strength of the real part. It's clear what you can do.

(Embodiment 3) This embodiment shows an example of a strength / rigidity evaluation process using both a strength evaluation using a resin model obtained by the method of the present invention and a simple FEM analysis. As shown in FIG. 13, first, a resin model is manufactured by a conventional optical molding method based on three-dimensional CAD of an actual part. Testing with this resin model and simple FE
Perform M analysis. That is, detailed analysis data of a reduced thickness portion, a weld bead portion, and the like are not created, and a rigidity evaluation (deformation analysis) governed by the cross-sectional shape and dimensions of the component is performed. Then, if the rigidity evaluation is good, a resin model using the method of the present invention is manufactured, and strength evaluation (stress and strain measurement) governed by local shapes of the sheet thickness reduced portion and the weld bead portion is performed.

As described above, by combining the rigidity evaluation by the simple FEM analysis and the local strength evaluation using the resin model according to the present invention, a large strength and
Stiffness evaluation can be performed.

[0028]

As described above in detail, according to the method for manufacturing a resin model of the present invention, it is possible to simulate the reduction in the thickness of a real part when press-forming an actual part and the penetration at a weld bead portion. If a strength test or the like is performed on the resin model obtained by the method of the present invention, accurate strength evaluation can be performed in consideration of a change in plate thickness during press molding and penetration of a weld bead portion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state of heat welding using a resin welding rod according to Example 1.

FIG. 2 is a perspective view of a resin model according to the first embodiment.

FIG. 3 is a front view showing a state of strength evaluation using a strain gauge according to the first embodiment.

FIG. 4 is a graph showing a result of strain measurement for an actual part and a resin model according to the first embodiment.

FIG. 5 is a graph showing a result of strain measurement on an actual part and a resin model according to the first embodiment.

FIG. 6 is a plan view of a resin model according to the second embodiment.

FIG. 7 is a graph showing a measurement result of a plate thickness distribution along a line AA in FIG. 6 for an actual part and a resin model according to Example 2.

FIG. 8 is a graph showing a measurement result of a plate thickness distribution along a line BB in FIG. 6 for an actual part and a resin model according to Example 2.

FIG. 9 is a graph showing a measurement result of a thickness distribution on the line CC of FIG. 6 for the actual part and the resin model according to the second embodiment.

FIG. 10 is a plan view showing a state of strength evaluation using a strain gauge according to Example 2.

FIG. 11 is a graph showing a result of strain measurement for an actual part and a resin model according to the second embodiment.

FIG. 12 is a graph showing a result of strain measurement for an actual part and a resin model according to Example 2.

FIG. 13 is a flowchart illustrating a strength / rigidity evaluation process using a resin model obtained by the method of the present invention and a simple FEM analysis in accordance with the third embodiment.

[Description of Signs] 1 ... Vacuum molded product, 2 ... Resin material, 3 ... Resin welding rod, 5, 6
… Resin model

Claims (1)

[Claims] 1. A step of vacuum-forming one resin plate made of a thermoplastic resin into a predetermined shape to obtain a vacuum-formed product, and laminating or butting another resin material made of a thermoplastic resin on the vacuum-formed product. And thermally welding a resin welding rod made of a thermoplastic resin to the overlapped portion or the butt portion.