JP2003048195A - Method of cutting sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothen a cut edge of a sheet. SOLUTION: In this method of cutting the sheet 8, a metal cutting edge 4 is bitten in to the thermally softened resin sheet 8 from its one face side, and retreated thereafter to cut the sheet 8, a metal knife edge bearing 6 brought into contact with the sheet 8 and the cutting edge 4, and a non-heat-conductive cushioning member 7 for supporting a reverse face of the edge bearing 6 are provided in the other face side of the sheet 8, and a thickness of the edge bearing 6 is made 0.7 mm or less. An unnecessary part in an outer side of the sheet 8 is preferably cut by the method hereinbefore, prior to pressure or vacuum forming of the thermally softened sheet 8. When the sheet 8 is made of an acrylic resin and has 1-3 mm of thickness, a temperature just before the cutting of the sheet 8 is preferably brought into about 120-150 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting a heat-softened sheet, and more particularly to a method for cutting a sheet suitable for cutting the heat-softened sheet prior to pressure forming or vacuum forming.

[0002]

2. Description of the Related Art For heat-softened resin sheets,
A method of cutting the sheet by cutting a cutting blade from one side thereof is known. In this case, a die arranged for the other surface of the sheet facing the cutting blade is also used as a die for vacuum or compressed air forming.

[0003]

Then, the heat-softened sheet is cooled by the contact with the mold, so that the cutting edge of the sheet is sharpened and the finger is easily injured. It should be noted that there is. In view of such problems to be solved, the present invention aims to smooth the cutting edge of the sheet.

[0004]

[Means for Solving the Problems] As described in the claims.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described, but it is merely an exemplary embodiment adopted based on the present invention, and the present invention is based on matters peculiar to the embodiment. However, the technical scope of the present invention should be determined based on the matters shown in the claims and the matters substantially equivalent to the matters.

The embodiment shown in the drawings shows the outer peripheral portion of a vacuum or compressed air forming apparatus having a metal lower mold 1 and an upper mold 2 as main elements. An annular pressing member 3 made of silicon rubber is fixed to the lower mold 1 and the upper mold 2 so as to face each other in an airtight manner. An annular cutting blade 4 made of metal and having a tapered tip is held by an annular blade holder 5 which is also vertically movable on the outer periphery of the lower die 1, and the tip side of the cutting blade 4 penetrates a part of the lower die 1. It is possible. An annular blade support 6 made of steel and facing the cutting blade 4 and an annular non-heat-conducting cushion material (made of urethane rubber) 7 fixed to the back surface of the blade support 6 are provided in the lower surface recess of the upper mold 2. I have it. The blade receiver 6 has a thickness of 0.5 to 0.7 mm.

In FIG. 1, first, with the lower mold 1 and the upper mold 2 open, a heat-softened resin sheet 8 is placed on the upper surface of the lower mold 1. The temperature of the sheet 8 at this time is 120 when the sheet 8 is made of acrylic resin and has a thickness of 1 to 3 mm.
It is preferable to set the temperature to about 150 ° C. When the sheet 8 is heat-softened by a heater (not shown) provided outside the lower mold 1, and then transferred to the upper surface of the lower mold 1, 120 to 120 in the state of FIG.
Set to about 150 ° C. Immediately thereafter, as shown in FIG. 2, the upper mold 2 is lowered to clamp the sheet 8. In this state, the pressing members 3 clamp the sheet 8 in the airtight manner. Further, although the blade receiver 6 contacts the sheet 8, since the blade receiver 6 is thin, the temperature of the sheet 8 is unlikely to be locally reduced. Immediately thereafter, as shown in FIGS. 3 to 4, the blade holder 5 is lifted to cause the cutting blade 4 to bite from one side of the sheet 8 to cut the sheet 8. 4, the blade holder 5 and the cutting blade 4 are further raised, the blade receiver 6 is further raised, and the cushion material 7 is largely elastically contracted as compared with FIG. It shows a state where the

Immediately thereafter, as shown in FIG. 5, when the blade holder 5 and the cutting blade 4 are lowered and retracted, the sheet 8 is kept cut. Then, in this state, on the right side, which is the center side of the sheet 8, the sheet 8 is vacuum- or pressure-formed to form a globe for a lighting fixture or the like. Since this molding method itself is known and is not directly related to the present invention, no explanation is required. Then, when this molding is finished, as shown in FIG.
To remove the molded product. And FIG.
In the above, the portion on the left side of the cut portion on the outer side of the sheet 8 is an unnecessary portion.

In FIG. 7 (A), the upper edge of the cutting portion of the sheet 8 is pointed obliquely upward when the cutting blade 4 is cut into the sheet 8, but when the cutting blade 4 is retracted, as shown in FIG. 7 (B). The sharpness of the upper edge of the cut portion of the sheet 8 returns to become rounded. As described above, when the sheet 8 is cut, the sheet 8
If the blade receiver 6 that abuts is thin, the sheet 8 is less likely to be cooled, so that the upper edge of the cutting portion of the sheet 8 is not sharp, and the cutting edge of the sheet 8 can be made smooth. In addition, since the blade receiver 6 is made of metal, damage due to contact with the cutting blade 4 is unlikely to proceed,
This is because the replacement frequency is low.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a first step.

FIG. 2 is a partial sectional view showing a second step.

FIG. 3 is a partial sectional view showing a third step.

FIG. 4 is a partial sectional view showing a fourth step.

FIG. 5 is a partial sectional view showing a fifth step.

FIG. 6 is a partial sectional view showing a sixth step.

FIG. 7A is a partial cross-sectional view showing a state where a cutting blade is bitten into a sheet, and FIG. 7B is a partial cross-sectional view showing a state where the cutting blade is retracted from the sheet.

[Explanation of symbols]

4 cutting blades 6 blade receiver 7 Cushion material 8 seats

Claims (3)

[Claims] 1. A heat-softened resin sheet,
A method of cutting the sheet by retracting the cutting blade made of metal from the one surface side, and cutting the sheet, in which the sheet and the cutting blade contact the sheet and the cutting blade on the other surface side of the sheet, and this A method of cutting a sheet, comprising a non-heat-conducting cushioning material that supports the back surface of the blade receiver, wherein the thickness of the blade receiver is 0.7 mm or less. 2. A method of cutting a sheet according to claim 1, wherein an unnecessary portion near the outside of the sheet is cut before pressure-pressing or vacuum forming the heat-softened sheet. 3. The method for cutting a sheet according to claim 1, wherein when the sheet is made of acrylic resin and has a thickness of 1 to 3 mm, the temperature immediately before cutting the sheet is about 120 to 150 ° C.