JP2002028970A - Method for detecting prestretch blow height and method for setting prestretch blow height in method for pressure forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting prestretch blow height and a method for setting prestretch blow height in a method for pressure forming by which the prestretch blow height can be surely detected and set. SOLUTION: When the neighborhood of the top of a prestretch-blown resin material 2 reaches the underside of a hole 8 and the hole 8 is closed with the resin material 2, pressure in a pipeline 9 is elevated. Then, change in the pressure is detected by means of a pressure sensor 10 and a valve 5 is closed through a control part 11 based on this detection and the prestretch blow is stopped. In addition, air may not be preferably fed to the pipeline 9. Furthermore, it may be preferable that timer action for a specified time is performed by the control part 11 in such a way that stopping of the prestretch blow is performed at a specified time a little later after the change in pressure is detected by means of the pressure sensor 10. Then, when the prestretch blow is stopped, a servo motor 12 is actuated by the control part 11 to control lowering of a mold 7. Elevating, lowering and stopping of the mold 7, opening and closing of the valve 5 and feeding/unfeeding of air into the pipeline 9 are controlled by a control signal from the control part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a pretensioning blow height and a method for setting a pretensioning blow height in a compressed air forming method.

[0002]

2. Description of the Related Art As a method of pressure-forming a glove for a lighting apparatus, particularly when pressure-forming a globe having an overhang portion having a diameter larger than the opening diameter, heat softening is performed between dies which are opposed to each other. There has been known a method in which a resin material is pre-stretched and blown, and then a mold is closed to perform pressure forming. As described above, by pre-expanding and blowing the resin material that has been thermally softened between the spaced-apart dies, it is easy to achieve uniform gloves in the event of final pressure forming. In this case, it is necessary to set the pre-blow height, but a laser beam has been used as a method for detecting the pre-blow height. That is, a large-diameter vertical hole is provided substantially at the center of the pedestal on the side where the resin material to be pre-blown is away, and a laser light emitter directed upward and a light receiver receiving reflected laser light from above are provided in the hole. To measure the height of the resin material blown and blown to the lower surface of the apex.

[0003]

However, in the measurement method using a laser beam, noise is likely to be applied to the light receiving device, so that erroneous measurement occurs, and the height cannot be detected with a resin material that is almost transparent. It should be noted that there are challenges. The present invention has been made in view of such a problem to be solved,
An object of the present invention is to provide a method for detecting a pretensioning blow height and a method for setting a pretensioning blow height in a compressed air molding method capable of reliably detecting and setting a pretensioning blow height.

[0004]

Means for solving the problems are as described in the claims.

[0005]

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

FIG. 1 to FIG. 6 sequentially show the pressure forming process. In FIG. 1, a thermally softened resin material 2 is set on an upper surface of a pedestal 1 and clamped by dies 3a and 3b formed by dividing an outer peripheral portion of the resin material 2 in a horizontal plane. A vertical hole 4 is formed substantially at the center of the pedestal 1, and a lower end of the hole 4 is connected to a pipe 6 provided with a valve 5 on the way, so that air can be supplied from an end of the pipe 6. . A mold 7 is provided to face the molds 3a and 3b, and the mold 7 is provided so as to be vertically movable. One or a plurality of holes 8 (preferably small holes) are provided facing substantially the center of the inner surface of the mold 7 and the holes 8 are formed.
A pipe 9 for blowing or sucking air from outside to the outside, and a pressure sensor 10 for detecting a pressure in the pipe 9
Is provided. In FIG. 1, when the mold 7 is lowered to a predetermined position, the process proceeds to the step of FIG.

FIG. 2 shows molds 3a and 3b-
The process of prestressing and blowing the resin material 2 that has been thermally softened between the molds 7 is shown. In this step, the valve 5 is opened and the air blow is sent from the upper end of the hole 4 to the lower surface of the resin material 2 so that the resin material 2 expands. A relatively low-pressure air is supplied to the pipe 9, and the air is blown out from the lower end of the hole 8.
Of course, air is drawn in from the pipe 9 at a relatively low pressure,
The air may be sucked from the lower end of the hole 8. The point is that a hole 8 is provided substantially at the center of the inner surface of the mold 7 on the side where the resin material 2 to be pre-blown is approached, and air may be blown or sucked into the hole 8 from the outside.

Next, FIG. 3 shows a final step of the pre-expansion blow. As shown in this drawing, when the vicinity of the apex of the pre-stretched blown resin material 2 reaches the lower surface of the hole 8 and the hole 8 is closed by the resin material 2, the pressure in the pipe 9 increases. Then, the pressure change is detected by the pressure sensor 10, and based on this detection, the valve 5 is closed via the control unit 11, and the pretensioning blow is stopped. It is preferable that air is not supplied to the pipe 9. The control unit 11 may cause the control unit 11 to perform a timer operation for a predetermined time so that the pre-expansion blow is stopped a predetermined time slightly after the pressure change is detected by the pressure sensor 10. And when the pre-expansion blow is stopped,
The control unit 11 operates the servomotor 12 to control the lowering of the mold 7. In addition, the raising, lowering, and stopping of the mold 7 by the servo motor 12, the opening and closing of the valve 5, and the supply / non-supply of air to the pipe 9 are controlled by control signals from the control unit 11.

Next, FIG. 4 shows that the mold 7 is lowered to the mold 3a.
3b shows a state in which the molds 3a and 3b and the mold 7 are closed. In this state, the valve 5 is opened, and air is finally sent into the resin material 2 to perform air pressure molding. Then, after molding, the valve 5 is closed, and then the mold 7 is raised as shown in FIG. 5, and further, as shown in FIG.
After b is separated in the horizontal direction, the resin material as a molded product, that is, the globe 2 is taken out.

In the embodiment described above, the resin material 2 thermally softened between the dies 3a and 3b and the die 7 which are opposed to each other is pre-stretched and blown by the pre-stretched resin material 2. 8, when the pressure change in the pipe 9 is detected by the pressure sensor 10, a pretension blow height detection method, and a pretension blow height setting at which the pretension blow is stopped based on this detection. Since this method is used, there is an advantage that the height of the pretensioning blow can be reliably detected, and the pretensioning blow can be reliably stopped based on this detection.

[Brief description of the drawings]

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

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

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

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

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

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

[Explanation of symbols]

 2 Resin material 3a ・ 3b Mold 7 Mold 8 Hole 9 Piping 10 Pressure sensor

Claims (2)

[Claims] In a method of prestressing and blowing a resin material thermally softened between dies which are opposed to each other and then closing the mold to form a compressed air, a mold on a side to which the resin material to be prestrained and blown approaches. A hole is provided facing the center of the inner surface of the mold, and a pipe for blowing or sucking air from outside to the hole, and a pressure sensor for detecting the pressure in the pipe are provided. A pretensioning blow height detection method in which a pressure change in the pipe is detected by the pressure sensor when the hole is closed. 2. A method in which a resin material that has been thermally softened is pre-blow blown between dies that are opposed to each other, and then the mold is closed to form a compressed air. A hole is provided facing the center of the inner surface of the mold, and a pipe for blowing or sucking air from outside to the hole, and a pressure sensor for detecting the pressure in the pipe are provided. When the hole is closed, a pressure change in the pipe is detected by the pressure sensor,
A method for setting a pretension blow height in which the pretension blow is stopped based on this detection.