JP3790090B2 - Cutting method of hard synthetic resin material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cutting method for cutting a hard synthetic resin material into a desired shape.
[0002]
[Prior art]
A plate material made of a hard synthetic resin such as an acrylic resin is likely to crack when sheared at room temperature. When this type of synthetic resin sheet material is vacuum-formed or pressure-molded, the molding maker uses a standard-sized sheet material manufactured by the material maker by extrusion or casting, etc., and has a rectangular size according to the product shape. It is cut with a circular saw or a band saw and then secondary processed. Further, in the case of vacuum forming or pressure forming, the ear is cut after the forming process.
[0003]
According to the above manufacturing process,
・ Since ears and chips are generated, the material yield is low. ・ Productivity is low. (If the cutting shape is complicated, automation is difficult and the cutting speed is slow.)
・ There is an inconvenience of generating a large amount of chips that cannot be recycled.
[0004]
As a cutting method that does not generate chips, a cutting blade formed into a shape to be cut, and an upper die and a lower die in which an elastic body is arranged around the cutting blade, a resin plate is placed between the upper and lower die, and the resin A technique has been proposed in which a cutting blade is driven into the upper and lower surfaces of the plate and cut (Japanese Patent Laid-Open No. 7-285099). This technique is used for an expensive punching die having a blade made of cemented carbide or the like and having an upper and lower die made of steel or the like.
[0005]
[Problems to be solved by the invention]
When the present inventor applied and tested the above technique to acrylic resins having various thicknesses, the following matters became clear.
-The cutting surface consists of an upper blade biting portion, a crack portion, and a lower blade biting portion.
・ When the plate thickness increases, the surface of the crack becomes rough.
-While the cutting edge of the cutting blade is sharp, the surface of the crack portion is smooth, but when the cutting edge becomes dull, the surface of the crack portion becomes rough.
・ If the amount of rubber added to the acrylic resin is increased, defects such as cracks, chips and whiskers are less likely to occur.
-Acrylic resin with a small amount of added rubber greatly changes the roughness of the surface of the crack portion depending on cutting conditions such as the amount of biting by the cutting blade, the thickness of the elastic body, and the hardness.
And according to the said invention, since the abrasion and damage of the blade edge of a cutting blade generate | occur | produce comparatively early, in order to obtain a smooth cut surface, frequent replacement | exchange of a cutting blade is required. Moreover, there is a disadvantage that the roughness of the cut surface obtained varies greatly due to changes in the material and plate thickness of the synthetic resin.
[0006]
It is an object of the present invention to provide a method for cutting a hard synthetic resin material in which a smooth cut surface can be obtained over a wide range of materials and plate thicknesses, and the life of the cutting blade is long.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following means.
The present invention, blades are opposed to protrude from the upper surface of the lower surface and the lower die substrate of the upper die substrate, the elastic body thicker than the protruding height of the blade is disposed on both sides of each blade of the vertical, the It is a method of cutting hard synthetic resin material by driving the blade edge of the opposing blade into the upper and lower surfaces of the plate material, and at the time of cutting, the blade edge of one type of blade comes into contact with one surface of the plate material and bites into the plate material. Next, the cutting edge of the blade on the other side comes into contact with the surface of the plate material, bites into it, and brittle fracture occurs from the cutting edge of the cutting tool on the other side to the cutting edge of the cutting tool on the one side. In the method of generating and cutting the plate material ,
When the distance between the lower surface of the upper elastic body and the blade edge of the blade is DU, and the distance between the upper surface of the lower elastic body and the blade edge of the blade is DL, the magnitude of the force compressing the upper elastic body by DU; It is characterized in that the magnitude of the force compressing the lower elastic body by DL is different.
[0008]
The above relationship can be realized by any of the following means.
(1) With DU = DL, the hardness of the upper elastic body is made different from the hardness of the lower elastic body. For example, when DU = DL, the hardness of the upper elastic body is made lower than the hardness of the lower elastic body.
(2) The hardness of the upper elastic body and the hardness of the lower elastic body are the same, and the lengths of DU and DL are made different. For example, the hardness of the upper elastic body and the hardness of the lower elastic body are the same, and a relationship of DU <DL is established.
(3) The lengths of DU and DL are different, and the hardness of the upper elastic body is made different from the hardness of the lower elastic body. For example, when DU <DL, the hardness of the upper elastic body is made lower than the hardness of the lower elastic body.
[0009]
In order to satisfy the above relationship, the elastic body may have a laminated structure of at least two layers having different hardnesses.
[0011]
The curvature radius of bending deformation is preferably in the range of 300 to 800 mm.
[0012]
When a hard synthetic resin plate is placed between the upper mold and the lower mold of the above-mentioned cutting mold and the cutting edges of the opposing blades are driven into the upper and lower surfaces of the workpiece, the upper elastic body is compressed by DU. Since the magnitude of the force is different from the magnitude of the force that compresses the lower mold elastic body by DL, the cutting edge of one type of blade first comes into contact with one surface of the plate material and bites into the other surface. Protrusively bends and deforms. At this time, a tensile stress perpendicular to the cut surface acts on the other surface side of the plate material due to bending deformation. Further, when pressed, the blade edge of the blade on the other side comes into contact with the surface of the plate material, bites into it, and brittle fracture occurs from the blade edge of the blade on the other surface side toward the blade edge of the blade on one surface side. Is cut into a predetermined punching shape. In this way, when cutting, the blade is driven on one surface side of the plate material in a state where a tensile stress perpendicular to the cutting surface is applied, so that the blade on the other surface side is cut from the blade edge of the blade on the other surface side. Since cracks are continuously generated toward the cutting edge, a smooth and good cut surface can be obtained. Moreover, since the amount of biting of the upper and lower knives is shallow and can be cut, the life of the knives can be extended.
[0013]
In the above, as the hard synthetic resin, thermoplastics such as general-purpose plastics such as polyvinyl chloride, polypropylene, ABS, polyethylene terephthalate resin, acrylic resins, polystyrene resins, methacryl-styrene copolymer resins, and styrene-acrylonitrile copolymer resins. Examples thereof include resins, thermosetting resins, and engineering plastics.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment 1 of the present invention will be described with reference to FIGS. In the drawing, the positioning holes and the like are omitted, and the relationship between the blade and the elastic body is illustrated.
[0015]
The cutting mold includes an upper mold 1 and a lower mold 2. The materials of the upper mold substrate 3 and the lower mold substrate 4 that form the upper mold 1 and the lower mold 2 are made of an Al alloy. The cutting die according to the present embodiment cuts a plate material from the end into a strip shape, and includes straight strip-shaped blades 5 and 6.
[0016]
The upper die substrate 3 and the lower die substrate 4 have cutter press-fitting portions 7 and 8 into which straight strip-like cutters 5 and 6 are press-fitted. The cutter press-fitting portion 7 of the upper mold substrate 3 includes a plurality of slit-like through holes 9 arranged on a straight line at intervals, and a groove 10 formed on the lower surface of the substrate 3 between the through holes 9. Has been. The through hole 9 and the groove 10 are formed perpendicular to the substrate 3 and have the same press-fitting width. The cutter press-fit portion 8 of the lower mold substrate 4 is formed at a position facing the cutter press-fit portion 7 of the upper mold substrate 3 with a through hole 11 and a groove 12 having the same structure and size as the cutter press-fit portion 7 of the upper mold substrate 3. It is configured. The groove 12 is formed on the upper surface of the lower mold substrate 4.
[0017]
As the blades 5 and 6 fixed to the upper mold substrate 3 and the lower mold substrate 4, Thomson blades or the like for cutting paper, sheets, rubber, or the like can be used. Each of the cutters 5 and 6 is a strip-like cutter having substantially the same size as the cutter press-fitting portions 7 and 8 of the upper mold substrate 3 and the lower mold substrate 4, respectively, and the blade edge angle is generally 30 to 55 degrees. The smaller the blade edge angle is, the more suitable for cutting a thick plate, but the life of the blade edge is shortened. When the widths of the through holes 9 and 11 and the grooves 10 and 12 of the cutter press-fitting portions 7 and 8 of the upper mold substrate 3 and the lower mold substrate 4 are slightly smaller than the thickness of the cutters 5 and 6 (1/100 to 3/100 mm). The blades 5 and 6 are securely fixed to the upper die substrate 3 and the lower die substrate 4, respectively, and the position accuracy of the blade edge can be improved.
[0018]
The longitudinal lengths of the blades 5 and 6 are longer than the thicknesses of the upper die substrate 3 and the lower die substrate 4, respectively. It has notches 13 and 14. The notches 13 and 14 are formed corresponding to the positions of the grooves 10 and 12 of the cutter press-fitting portions 7 and 8 formed in the upper mold substrate 3 and the lower mold substrate 4. Therefore, in a state in which the cutters 5 and 6 are press-fitted and fixed to the cutter press-fitting portions 7 and 8 of the upper die substrate 3 and the lower die substrate 4, the notches 13 and 14 of the cutters 5 and 6 are the cutter press-fitting portion 7. 8 are press-fitted into the grooves 10 and 12, and the portions where the notches 13 and 14 are not formed are press-fitted into the through-holes 9 and 11 of the cutter press-fitting portions 7 and 8. At this time, the end surfaces of the blades 5 and 6 opposite to the blade edges are fixed so as to be flush with the end surfaces of the upper mold substrate 3 and the lower mold substrate 4, thereby positioning the blades 5 and 6 in the vertical direction. The cutting edges of the blades 5 and 6 are arranged to protrude from the upper mold substrate 3 and the lower mold substrate 4 by a predetermined length, respectively.
[0019]
The protruding heights of the blade edges of the blades 5 and 6 from the surfaces of the upper mold substrate 3 and the lower mold substrate 4 are in the range of 2.5 to 6.0 mm. If the protruding height of the cutters 5 and 6 is too high, the positional accuracy of the cutting edge is lowered. However, if the protruding height is too small, there will be inconvenience in the configuration of the guide pin for positioning the object to be cut and the elastic body described later. A more preferable protrusion height is 3.0 to 5.0 mm.
[0020]
On the lower surface of the upper mold substrate 3, elastic bodies 15 and 16 having the same shape and the same size are arranged and fixed on both side surfaces of the blade 5. The elastic bodies 15 and 16 have a rectangular plate shape, are made of an elastic material such as a rubber sponge, and have a thickness slightly thicker than the protruding height of the blade 5. On the upper surface of the lower mold substrate 4, elastic bodies 17 and 18 having the same shape and the same size are arranged and fixed on both side surfaces of the blade 6. The elastic bodies 17 and 18 have a rectangular plate shape, are made of an elastic material such as a rubber sponge, and have a thickness slightly thicker than the protruding height of the blade 6.
[0021]
Here, when the distance between the lower surface of the elastic bodies 15 and 16 of the upper mold 1 and the blade edge of the blade 5 is DU, and the distance between the upper surface of the elastic bodies 17 and 18 of the lower mold 2 and the blade edge of the blade 6 is DL,
The size of the force for compressing the elastic bodies 15 and 16 of the upper mold 1 by DU <the magnitude of the force for compressing the elastic bodies 17 and 18 of the lower mold 2 by DL.
[0022]
In the present embodiment, in order to satisfy the above relationship, the hardness of the elastic bodies 15 and 16 of the upper mold 1 is set lower than the hardness of the elastic bodies 17 and 18 of the lower mold 2 and DU = DL. The elastic bodies 15 and 16 of the upper mold 1 have a hardness of 15 and the elastic bodies 17 and 18 of the lower mold 2 have a hardness of 25. Such a relationship is effective when the plate material is relatively thin.
[0023]
2 and 3, a plate material 20 drawn between the upper mold 1 and the lower mold 2 represents a hard synthetic resin plate that is an object to be cut.
[0024]
Next, a method for cutting a hard synthetic resin plate using the cutting die will be described.
[0025]
The aforementioned cutting die is set in a mechanical press or a hydraulic press. A hard synthetic resin plate 20 is placed between the set upper die 1 and lower die 2, and the cutting edges of the opposed cutters 5 and 6 are driven into the upper and lower surfaces of the workpiece.
[0026]
At this time,
Since the magnitude of the force compressing the elastic bodies 15 and 16 of the upper mold 1 by DU <the magnitude of the force compressing the elastic bodies 17 and 18 of the lower mold 2 by DL, there is a relationship between the blade of the upper mold 1 first. The cutting edge 5 comes into contact with the upper surface of the plate member 20 and bites into the plate member 20, and the lower surface of the plate member 20 is bent and deformed. At this time, tensile stress perpendicular to the cut surface acts on the lower surface side of the plate member 20 due to bending deformation. Further, when pressed, the cutting edge of the cutting tool 6 of the lower mold 2 comes into contact with the lower surface of the plate member 20 and bites, and brittle fracture occurs from the cutting edge of the cutting tool 6 of the lower mold 2 toward the cutting edge of the cutting tool 5 of the upper mold 1. The plate material 20 is cut into a predetermined punching shape. It is desirable that the radius of curvature of the bending deformation of the plate member 20 when the cutting edge of the blade 6 of the lower mold 2 contacts is in the range of 300 to 800 mm.
[0027]
In this way, when cutting, the cutting tool 6 of the lower mold 2 is driven into the lower surface side of the plate member 20 in a state where a tensile stress perpendicular to the cutting surface is applied, so that the upper mold is moved from the cutting edge of the cutting tool 6 of the lower mold 2. Since cracks are continuously generated toward the cutting edge of one blade 5, a smooth and good cut surface can be obtained. Moreover, since the amount of biting of the cutters 5 and 6 of the upper mold 1 and the lower mold 2 is shallow and can be cut, the life of the cutters 5 and 6 can be extended.
[0028]
The cutting depth of the cutting edge into the workpiece is 0.2 to 0.7 mm above and below. If the driving depth is too small, a portion that cannot be cut may be generated. If the driving depth is too large, the life of the cutting edge is shortened. Further, it is recognized that the cutting surface property tends to be slightly better when the driving speed is higher. However, if the thickness of the object to be cut is in the range of 0.8 to 5.0 mm, cutting is possible within the range of the press speed of a normal mechanical press or a hydraulic press slower than this.
[0029]
When the upper mold 1 and the lower mold 2 are separated after cutting, the cutting material is separated from the cutting edges of the blades 5 and 6 by the restoring force of the compressed elastic bodies 15, 16, 17, and 18 to the original shape, It is placed on the elastic bodies 17 and 18 of the lower mold 2.
[0030]
The cutting materials are arranged in the order of the biting portion of the cutting tool 5 of the upper die 1, the crack portion, and the biting portion of the cutting tool 6 of the lower die 2, and the length of the biting portion of the cutting tool 5 of the upper die 1 is lower. It is larger than the length of the biting portion of the cutter 6 of the mold 2.
[0031]
FIG. 4 shows another embodiment 2 of the present invention. The second embodiment is different from the first embodiment only in the configuration of the elastic body, and the other configurations are the same. In the elastic body of the second embodiment, the hardness of the elastic bodies 15 and 16 of the upper mold 1 is lower than the hardness of the elastic bodies 17 and 18 of the lower mold 2 and DU <DL. The elastic bodies 15 and 16 of the upper mold 1 have a hardness of 15 and the elastic bodies 17 and 18 of the lower mold 2 have a hardness of 25. Such a relationship is effective when the plate material is thick.
[0032]
FIG. 5 shows still another embodiment 3 of the present invention. The third embodiment is different from the first embodiment only in the configuration of the elastic body, and the other configurations are the same. In the third embodiment, the elastic bodies 15 and 16 of the upper mold 1 and the elastic bodies 17 and 18 of the lower mold 2 are respectively formed in a two-layer laminated structure having different hardness. And the hardness of the elastic bodies 15 and 16 of the upper mold | type 1 is made lower than the hardness of the elastic bodies 17 and 18 of the lower mold | type 2, and it is DU = DL. One elastic body 15 of the upper mold 1 is formed by sequentially laminating an elastic body 15a (hardness 15) and an elastic body 15b (hardness 25) on the upper mold substrate 3, and the other elastic body 16 is also an elastic body 16a. (Hardness 15) and elastic body 16b (hardness 25) are formed on the upper mold substrate 3 in order. One elastic body 17 of the lower mold 2 is formed by sequentially laminating an elastic body 17a (hardness 35) and an elastic body 17b (hardness 25) on the lower mold substrate 4, and the other elastic body 18 is also an elastic body 18a. (Hardness 35) and an elastic body 18b (hardness 25) are formed on the lower mold substrate 4 in order.
[0033]
FIG. 6 shows yet another embodiment 4 of the present invention. The fourth embodiment is different from the first embodiment only in the configuration of the elastic body, and the other configurations are the same. In the fourth embodiment, the elastic bodies 15 and 16 of the upper mold 1 are formed of a single layer, and the elastic bodies 17 and 18 of the lower mold 2 are formed of a two-layer laminated structure having different hardnesses. And the hardness of the elastic bodies 15 and 16 of the upper mold | type 1 is made lower than the hardness of the elastic bodies 17 and 18 of the lower mold | type 2, and it is DU <DL. The hardness of the elastic bodies 15 and 16 of the upper mold 1 is a hardness of 25. One elastic body 17 of the lower mold 2 is formed by sequentially laminating an elastic body 17a (hardness 35) and an elastic body 17b (hardness 25) on the lower mold substrate 4, and the other elastic body 18 is also an elastic body 18a. (Hardness 35) and an elastic body 18b (hardness 25) are formed on the lower mold substrate 4 in order.
[0034]
When the cutting test of various acrylic resin plates with the thickness of 0.8 to 5 mm and the material of 0 to 30% of rubber was performed with the cutting die described above, an inexpensive Thomson blade was used. Nevertheless, a good cut surface was obtained even after cutting 30,000 times, and the effect of the present invention was confirmed.
[0035]
The present invention is not limited to the above embodiment. For example, when DU> DL, the hardness of the elastic bodies 15 and 16 of the upper mold 1 is made lower than the hardness of the elastic bodies 17 and 18 of the lower mold 2. By
It is also possible to realize the relationship of the magnitude of the force that compresses the elastic bodies 15 and 16 of the upper mold 1 by DU <the magnitude of the force that compresses the elastic bodies 17 and 18 of the lower mold 2 by DL.
Further, the present invention is contrary to the above embodiment,
Of course, the elastic bodies 15 and 16 of the upper mold 1 may be configured so as to satisfy the relationship of the magnitude of the force compressing the elastic bodies 17 and 18 of the lower mold 2 by DL.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method for cutting a hard synthetic resin material that can provide a smooth and good cut surface over a wide range of materials and plate thicknesses and has a long cutting blade life.
[Brief description of the drawings]
FIG. 1 is a plan view of a cutting die used in the cutting method of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is a cross-sectional view corresponding to FIG. 2, showing another cutting die used in the cutting method of the present invention.
FIG. 5 is a sectional view corresponding to FIG. 2, showing still another cutting die used in the cutting method of the present invention.
FIG. 6 is a sectional view corresponding to FIG. 2, showing still another cutting die used in the cutting method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper mold | type 2 Lower mold | type 3 Upper mold | type board | substrate 4 Lower mold | type board | substrate 5,6 Cutlery 7,8 Blade press-fit part 9,11 Through-hole 10,12 Groove 13,14 Notch 15,16,17,18 Elastic body 20 Hard body Synthetic resin board

Claims (7)

Cutlery is arranged to protrude from the lower surface of the upper mold substrate and the upper surface of the lower mold substrate, and elastic bodies having a thickness thicker than the protruding height of the cutter are arranged on both side surfaces of the upper and lower blades. This is a method of cutting a hard synthetic resin material by driving the blade edge onto the upper and lower surfaces of the plate material. At the time of cutting, the blade edge of one type of blade comes into contact with one surface of the plate material, biting into it, and bending deformation occurs in the plate material. Next, the blade edge of the blade on the other surface side contacts the surface of the plate material, bites into the plate material, causing brittle fracture from the blade edge of the blade on the other surface side toward the blade edge of the blade on the one surface side. In the method of cutting
When the distance between the lower surface of the upper elastic body and the blade edge of the blade is DU, and the distance between the upper surface of the lower elastic body and the blade edge of the blade is DL, the magnitude of the force compressing the upper elastic body by DU; A method of cutting a hard synthetic resin material, characterized in that the magnitude of the force compressing the lower elastic body by DL is different. 2. The method for cutting a hard synthetic resin material according to claim 1, wherein the hardness of the upper elastic body is different from the hardness of the lower elastic body when DU = DL. 2. The method for cutting a hard synthetic resin material according to claim 1, wherein the lengths of DU and DL are different, and the hardness of the upper elastic body and the hardness of the lower elastic body are the same. 2. The method for cutting a hard synthetic resin material according to claim 1, wherein the lengths of DU and DL are different, and the hardness of the upper elastic body and the hardness of the lower elastic body are different. The method for cutting a hard synthetic resin material according to any one of claims 1 to 4, wherein the elastic body has a laminated structure of at least two layers having different hardnesses. The cutting method for a hard synthetic resin material according to any one of claims 1 to 5, wherein the blade is a Thomson blade. The method for cutting a hard synthetic resin material according to any one of claims 1 to 6, wherein a radius of curvature of bending deformation is in a range of 300 to 800 mm.

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