JP3058025U - Compressed air forming equipment - Google Patents

Abstract

(57) [Summary] (Corrected) [PROBLEMS] To provide a compressed air molding device that reduces the resistance applied to a blade when cutting a plastic sheet and prevents chips from adversely affecting the next molding in the production of a compressed air molded product having an undercut. I do. A forming device including a lower split mold 1 and an upper split mold 3, a driving device for opening and closing the forming die, and a driving device for moving each split mold of the lower split die 1 into and out of an undercut portion. And a pressurizing device 17 having a clamp frame for clamping the heat-softened plastic sheet 21, wherein an annular groove is provided inside the clamp position on the lower surface of the lower split mold 1,
An annular male blade that engages with the annular groove, the male blade whose height of the cutting edge increases and decreases along the circumference, and an annular pressing member are provided on the air pressure device 17, and after molding, the air pressure device 17 is lowered. A driving device is provided for pressing the side mold 1 to cut the sheet.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a press forming apparatus for a plastic sheet, and more particularly, to an undercut, which is a flat dome-shaped molded product, in which the base of the dome having an opening is narrower and narrower than the outer shape of the dome. The present invention relates to an apparatus for producing a molded article having a shape.

[0002]

[Prior art]

 Pressure forming is a method of forming a predetermined shape by heating and softening a thermoplastic plastic sheet, applying pressure by compressed air to the sheet, and bringing the sheet into close contact with a mold as necessary. This molding method is relatively easy to produce, has low equipment costs, has good productivity, and is suitable not only for mass production but also for small production. It has advantages such as excellent mechanical strength. For this reason, compressed air molding is used for refrigerator inner boxes, back doors, OA equipment cases, automotive interior goods, washstands, washbasins, bathtubs, lighting covers, etc., as well as signboards, frozen dessert containers, egg packs, etc. Widely used in the production of molded products.

A method and an apparatus for forming a dome-shaped molded product having an undercut in an opening, for example, an illumination cover or the like with an extremely uniform thickness without reducing the thickness of the undercut portion by a compressed air type are particularly known. This is disclosed in Japanese Unexamined Patent Publication No. Hei. This device comprises: (1) an upper split mold comprising a plurality of split molds, each of which has a clamp opening and a molding surface extending to the side from the diameter of the clamp opening; A lower mold having a flat dome-shaped molding surface which can move relatively vertically, and (2) the lower mold is vertically moved relative to the upper mold. (3) a pneumatic device capable of air-tightly clamping the plastic sheet around the clamp opening of the upper split mold; A sensor for detecting that the apex position of the free blow dome generated by free blow downward has reached a predetermined position; and (5) an airlock of the compressed air device in response to the detection signal from the sensor. To (6) relative upward movement of the lower split mold to the upper split mold by the driving device in response to the detection signal from the sensor; And (7) pressing the lower split mold and the upper split mold into the molding die via the compressed air device after the lower split mold and the upper split mold are integrated. A compressed air forming apparatus for introducing air, comprising: the air inflow / outflow control apparatus and an integrated or separate air inflow control apparatus. This publication discloses a molding method in which a strict free blow amount is defined so that an undercut portion of a molded product can have substantially the same thickness as another portion with respect to an increase in area from a sheet to a molded product. Wherein the apparatus is adapted to perform the method.

[0004] Apparatus suitable for both molded articles having an undercut and molded articles without an undercut, and capable of executing cutting without having to once take out a primary molded article from a molding apparatus when cutting a molded article from a surplus sheet after molding. Is disclosed in Utility Model Registration No. 3047773. The apparatus is provided with a flange around the opening prior to removal from a mold after molding from a primary molded product having an excess sheet around the opening, which is obtained by air pressure molding of a sheet-like plastic. An apparatus for cutting out a molded article from a surplus sheet, comprising: (1) a mold having an opening corresponding to an opening of the primary molded article; and (2) a mold having an unformed sheet on an outer surface of the mold. And (3) an outer surface of the mold that comes into contact with the pre-formed sheet inside a position where the clamp frame is pressed, so as to surround the opening of the mold. And (4) (a) being arranged and arranged to engage with the annular groove and cooperate to cut the sheet. Do not touch the high An annular male blade of (b) disposed along the inside of the male blade, the distal end surface of which protrudes from the same height or higher than the distal end of the male blade, The metal annular presser which is located at a height where the sheet is not pressed during the operation, and whose tip surface can be retracted from the height of the tip of the male blade, is supported by a spring and arranged. The member is provided on a common base that moves together, and (5) the approach between the common base and the mold is such that the tip of the male blade abuts against the bottom of the annular groove. A stop mechanism is provided between the common base and the mold to prevent the male mold blade from stopping at a predetermined limit, and (6) for accurately aligning the male blade with the annular groove, A positioning mechanism is provided between the mold and the common base, and (7) after pressure forming, Before the sheet area on the annular groove is hardened, the base is pushed toward the outer surface of the mold to bring the base closer to the outer surface of the mold, so that the annular pressing member is pressed against the sheet and is pressed by the male blade. The apparatus according to claim 1, further comprising a driving device capable of sequentially cutting the sheet and stopping the approach between the base and the mold by the stopping mechanism.

[0005] The first feature of the apparatus is that the pressure required for cutting is reduced by suppressing the cooling of a region along the cutting portion later in the pressure forming compared to other sheet regions. Therefore, cutting around the opening of the molded product having a deep and narrow undercut is facilitated.

In other words, according to this apparatus, after the press forming, the sheet contacts the mold in the area of the annular groove where the blade is to be pushed in the excess sheet portion of the primary molded product still held by the mold and the clamp frame. Since the cutting is not performed, the cooling of the area is suppressed, and the cutting can be performed while the area is softer than other sheet portions. Therefore, the pressure required for the cutting can be relatively reduced, and the blade for performing the cutting is supported. The required strength of the resulting structure was also relatively reduced.

However, even when the sheet is relatively soft, when the tip of the annular male blade hits the sheet and cuts it, it is still necessary to avoid considerable resistance along the entire circumference of the cut portion. I couldn't.

Further, the apparatus disclosed in Japanese Patent Application Laid-Open No. HEI 8-118464 can work in the same way as an apparatus in which the apparatus is turned upside down. In some cases, fine chips generated by cutting after molding may fall into the flat dome-shaped lower split mold, and if the chips are not completely removed, scratches will be left on the surface of the next molded product There was a problem.

[0009]

[Problems to be solved by the invention]

 A first object of the present invention is to provide a compressed air forming apparatus capable of further reducing the resistance of a blade when cutting a plastic sheet in the production of a molded article having an undercut.

[0010] Still another object of the present invention is to provide a compressed air molding apparatus which eliminates the possibility that chips generated by cutting after molding will adversely affect the next molded article.

[0011]

[Means for Solving the Problems]

 That is, the present invention relates to a compressed air forming apparatus, comprising: (1) a lower split mold for forming an undercut portion, which has a clamp opening, and has a molding surface extending laterally from the clamp opening inside. A lower split mold composed of a plurality of partial split molds that can be divided in the horizontal direction; (2) a driving device for opening and closing the upper split mold in the vertical direction with respect to the lower split mold; and (3) components forming the lower split mold. A driving device for moving the split mold in and out of the undercut portion in the horizontal direction; and (4) the heat-softened plastic sheet is placed on the lower surface of the lower split mold from below with respect to the periphery of the clamp opening. Pressure with clamp frame that can be clamped to air tight (5) An annular groove surrounding the clamp opening is provided on the lower surface of the lower split mold that comes into contact with the plastic sheet inside the clamp position by the clamp frame. (6) (a) It is configured to engage with the annular groove and cooperate with the annular groove to cut the sheet. However, even if the plastic sheet is clamped to the airtight, the cutting edge reaches the plastic sheet. An annular male blade having a height not to be changed, wherein the height of the blade edge increases and decreases along the circumference; and (b) the male blade is arranged along the inside of the male blade. In addition, the upper surface may protrude from the highest tip of the male blade, but is supported by a spring so that the plastic sheet is located at a height at which the plastic sheet cannot be pressed during molding of the plastic sheet by pressurized air. Being arranged And (7) after the compressed air forming, the compressed air device is further pressed against the lower split mold, whereby the annular pressed member is used. There is provided an apparatus provided with a drive device capable of sequentially pressing the plastic sheet against the lower surface of the lower split mold and cutting the plastic sheet by the male blade. .

Since the present invention is configured as described above, when cutting the excess sheet after molding, the cooling of the sheet in the cutting area can be suppressed and the cutting can be performed while the sheet is relatively soft. Starting at the highest part of the blade's annular tip and moving to the lowest part, cutting can be achieved with a small pressure without applying all pressure to the blade at once. Become. This contributes to lighter equipment, lower energy consumption, and cost reduction. In addition, since the split mold having the flat dome-shaped forming surface is located on the upper side and the dome-shaped forming surface faces downward, chips from the sheet do not fall on this forming surface. Therefore, there is an advantage in that there is no possibility that chips formed on the surface of the molded article will be scratched by chips dropped on the molding surface as in the related art. Furthermore, since the molded article is placed on the surplus sheet after cutting, the excess sheet is easily taken out by holding the extra sheet, for example, by sucking its four corners, and taking it out horizontally. be able to. Furthermore, since the dome-shaped molded product can be taken out in a prone direction, deformation, damage, and the possibility of dust adhesion after taking out are minimized.

[0013] Further, the present invention is the above device, wherein the height of the cutting edge of the male blade is increased or decreased so as to form a plurality of peaks and valleys along the circumference. Also provide. Such a configuration helps to prevent streaks in the cutting direction from remaining on the cut surface of the product.

[0014] The present invention further provides the above device, further characterized in that the plurality of peaks and valleys are evenly arranged along the circumference. Such a configuration ensures that the pressure from the clamp frame and the male blade is applied to the upper split mold in a well-balanced manner during cutting, and reduces the load on the support structure of the upper split mold and the lower split mold. be able to.

[0015] Further, the present invention is further characterized in that, in the configuration of the male blade, the height of the blade edge has a step comprising at least a pair of convex portions and a concave portion between them along the circumference. Equipment shall be provided. Such a shape of the male blade has a sufficient effect of reducing the pressure required for cutting, though it is easy to manufacture. The protrusions and recesses can be arranged as appropriate, but are preferably arranged so that the overall pressure applied to the male blade during cutting is balanced.

Further, the present invention is the above-mentioned device, further comprising: (7) that the apex of the free blow dome generated by free-blowing the plastic sheet above the clamp opening reaches a predetermined height. (8) an air access control device for air-locking the compressed air device in response to a detection signal from the sensor, and an upper split mold and a lower split mold associated therewith And (9) an air access control device integral with or separate from the air access control device for introducing compressed air into the molding die after the mold is closed. There is also provided an apparatus comprising:

Such an apparatus is particularly suitable for producing a compressed air molded article having a uniform thickness undercut according to the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-118464. The sensor used here may be an appropriate one, and it is particularly preferable to use an optical sensor combined with an arbitrary light source. By free-blowing to the optimum height, airlocking and closing the mold, the free-blow dome is pushed out to the side and an undercut is formed, but the thickness of the free-blow dome is limited to the opening. Since the thickness is closer, the undercut portion is appropriately stretched at the time of mold clamping, so that it is possible to finally obtain a molded product having a very uniform thickness.

Further, the present invention is the above-mentioned device, wherein the upper split mold is supported from above by a motor-driven support member at the center thereof so as to be able to ascend and descend. An apparatus is also provided. In this configuration, since the upper split mold is supported at the center, the pressing force acting on the mold when pressing the clamp frame or cutting the excess sheet portion acts on the center in a well-balanced manner, and the fine shape due to the elastic deformation of the mold No problem such as warpage occurs, and there is no possibility that defective clamping or defective cutting will occur. Motor driving of the support member enables precise and quick position control as compared to hydraulic pressure.

Further, the present invention is directed to the above-mentioned apparatus, which is a compressed air device in which the clamp frame is pressed against the lower split mold and the mold is clamped when the mold is attached, and the correct water of the lower split mold and the upper split mold is adjusted. In order to position the flat positions with respect to each other, a positioning hole, which may be a bolt hole, is provided vertically through the upper split mold and the lower split mold to the compressed air device, and constitutes at least the lower split mold. The present invention also provides an apparatus further characterized in that the apparatus is provided for each divided type. According to this configuration, when mounting the mold, by passing a bolt or the like through the positioning hole, the mutual correct positional relationship between the compressed air device, the lower split mold and the upper split mold can be determined easily and precisely. It is possible to easily determine a mutual correct positional relationship to be taken when the male blade provided on the compressed air device and the annular groove provided on the lower split mold are clamped. After these parts are once precisely positioned and mounted on each drive based on the positions, the positioning members such as bolts are removed.

Further, the present invention is the above device, wherein a stopper for preventing the cutting edge of the male blade from abutting against the bottom of the annular groove is provided between the lower split die and the compressed air device. There is also provided an apparatus further characterized in that the apparatus is provided in the apparatus. As the stopper, a member such as a block having a predetermined size that reliably prevents the lower split mold and the compressed air device from approaching more than a predetermined amount may be provided on the compressed air device or on the lower surface of the lower split mold.

Further, the present invention is the above apparatus, wherein the guide for precisely positioning the annular groove of the lower split mold with respect to the male blade is provided by the lower split mold and the compressed air. An apparatus further provided between the apparatus and the apparatus is also provided. Such a guide prevents a slight displacement of the position between the male blade and the annular groove despite the insertion and removal of the lower split mold into and from the undercut portion performed at each molding step. it can. An example of a preferable guide is constituted by a combination of a vertical hole provided in the lower split mold and a positioning bar having a vertical tapered end provided on the upper surface of the compressed air device.

[0022]

[Embodiment of the invention]

 The molding dies in the device of the present invention include a lower split mold having a clamp opening of an appropriate shape such as a circle, an ellipse, and a polygon, and a flat dome shape (the horizontal cross section is also an appropriate shape. And the upper split mold having a forming surface of (good). When the two split molds are integrated, a flat dome-shaped forming surface is formed as a whole, which extends laterally beyond the diameter of the clamp opening. At the start of the pressure forming, these split dies are arranged vertically apart. After a predetermined free blow, the free blow dome is expanded by air-locking and clamping, and then pressurized air is injected to complete the molding. Hereinafter, typical modes and operations of the device of the present invention will be described.

[Mounting of Mold on Apparatus] A lower split mold is arranged in accordance with the male blade on the compressed air apparatus side. The lower split mold may be composed of, for example, two divided molds which are divided right and left at a clamp center line, or four divided molds which are divided into four quadrants in a plan view. Alternatively, it may be composed of an appropriate number of part-split types. The upper split mold is arranged on the lower split mold. In this state, bolts are inserted through holes that are vertically drilled through the respective split molds from the upper split mold to the lower split mold to the compressed air device, and these parts are connected to each other in the correct positional relationship. You. The bolts are then removed after each part is attached to its respective drive.

[Molding Step 1] The upper split mold is separated upward by the driving device, the compressed air device is similarly separated downward from the lower split die, and the respective split dies forming the lower split die are horizontally moved by the driving device. After being moved outward, the heat-softened synthetic resin sheet is placed on the clamp frame of the compressed air device. The clamp frame may be a ring-shaped member made of an elastic member such as silicon rubber. Next, the part split molds are returned inward to form the lower split mold. Subsequently, the pneumatic device is driven upward, and the clamp frame presses the sheet against the lower split mold and clamps the sheet to air tightness.

[Molding Step 2] Pressurized air is injected into the compressed air device, whereby the sheet is blown and swells upward from the clamp opening. The extent to which free blow is performed is appropriately set based on the area of the molded article and the initial area of the sheet portion to be blown. The guidelines disclosed in 8-118484 can be used.

When the top position of the free blow dome reaches a preset position, the compressed air device is air-locked. The position of the apex of the free blow dome may be detected, for example, by using an appropriate light source and an optical sensor.The signal from the optical sensor is used to stop the injection of pressurized air into the compressed air device and lock the air in / out. The air access control device is set as shown.

Next, the upper split die descends toward the lower split die, or the lower split die rises together with the compressed air device toward the upper split die, whereby the free die sandwiched between the split dies is formed. The blow dome is spread out and almost shaped into the shape of the product as the mold is clamped. After the mold is clamped, the compressed air is injected into the mold to finally form a shape. A drive control device associated with the mold is set in advance so that mold clamping starts with the end of free blow. In addition, an air access control device is set so that compressed air is injected into the mold after the completion of mold clamping.

Subsequently, the air pressure in the mold is released from the compressed air device, and then the compressed air device is further pressed against the lower split mold, and the clamp frame is elastically deformed and somewhat flattened. The distance from the side split mold is further reduced, and the annular male blade provided in the compressed air device cuts into the annular groove of the sheet lower split mold to cut the excess sheet. The cutting edge of the male blade is provided with a height along the circumference, and preferably comprises two or more peaks and a valley between them, and the height of the blade between each peak and the valley. It is continuously increasing and decreasing. The peak of each peak and the bottom of each valley may form a sharp corner or corner, but more preferably have a smooth shape. The arrangement of the peaks and valleys along the circumference may be such that the pressure applied during cutting is evenly distributed with respect to the center, and a preferable example is that the peaks and valleys are equally spaced along the circumference. It is arranged. For convenience, a configuration including a plurality of convex portions and concave portions therebetween may be adopted.

After cutting, the compressed air device is lowered to separate from the lower split mold, and the upper and lower split molds are opened, and at the same time, the part split molds constituting the lower split mold are pulled out from the undercut portion. As a result, the molded product is placed on the excess sheet on the clamp frame of the compressed air device, and the product can be taken out by sucking and grasping the four corners of the excess sheet and taking out the product horizontally from the device. it can.

[0030]

【Example】

 Hereinafter, the present invention will be described in more detail with reference to Examples, but it is not intended that the present invention be limited to the Examples.

FIG. 1 is an elevational view, including a sectional view, showing an outline of the compressed air forming apparatus of the present invention. In the figures, 1 is a lower split mold for forming an undercut portion, and 3 is an upper split mold for forming a dome portion. Reference numeral 5 denotes an elevating shaft serving as a support member for the upper split die 3, which supports the upper split die 3 and the elevating frame 7 to which the upper split die 3 is attached from above. The elevating shaft 5 has, on its outer periphery, a screw thread meshing with the screw thread of the female screw 9 member that is driven to rotate, and the female screw member 9 supported by the outer frame 11 is driven by a motor to rotate around the vertical axis. As the shaft rotates, the elevating shaft 5 moves up and down to raise or lower the upper split mold 3 attached to the elevating frame 7.

The lower split mold 1 is configured so that it can be opened so as to be divided right and left at a central portion 13 and closed so as to be united at the central portion by the operation of a horizontal drive device (not shown). Below the lower split mold 1, there is provided an internal sealed pneumatic device 17 supported by a central elevating shaft 15. The elevating shaft 15 has a screw thread on its outer periphery that meshes with the screw thread of the female screw member 19 that is rotationally driven, so that the female screw member 19 is driven by a motor and rotates around a vertical axis. Accordingly, the elevating shaft 15 moves up and down, and raises or lowers the compressed air device 17 supported by the shaft. A plastic sheet 21 heated and softened is placed on the compressed air device 17 so as to cover the clamp frame.

FIG. 2 is an elevational view including a cross-sectional view showing a state in which the plastic sheet 21 placed on the clamp frame is pressed against the lower surface of the lower split mold 1 and clamped by raising the compressed air device 17. In the figure, the compressed air device 17 is pushed up by the elevating shaft 15 from the position shown in FIG. 1 and pressed against the lower surface of the lower split mold 1 to airtightly heat the softened sheet to the lower split mold 1 along the clamp frame. It works to make close contact. However, at this time, a male blade 35 described later does not substantially contact the plastic sheet 21.

FIG. 3 shows a state in which pressurized air is injected into the compressed air device 17 and the plastic sheet 21 is freely blown. If the height of the free blow is determined based on Japanese Patent Application Laid-Open No. HEI 8-1-1864, a molded article having a very uniform wall thickness can be obtained.

FIG. 4 shows that the injection of the pressurized air by the compressed air device 17 is stopped, the air lock is performed, and the lifting shaft 5 is lowered by the rotation of the female screw member 9, whereby the lifting frame 7 and the upper split mold 3 are formed. Is shown to push down the free blow dome. Since the free blow dome is flattened by this process, the thickness of the undercut portion is not reduced as compared with the case where the lower split mold 1 and the upper split mold 3 are clamped from the beginning and press-formed. After the upper split mold 3 is tightly fixed to the lower split mold 1 and is clamped, compressed air is injected into the mold by the compressed air device 17 to strongly press the plastic sheet 21 against the inner surface of the mold, thereby forming a molded product. The shape of 23 is finally adjusted.

FIG. 5 is a cross-sectional view of the apparatus showing a process of cutting a surplus sheet from a molded product. In the figure, a lower split mold 1 in this embodiment is composed of an upper first portion 1a and a lower second portion 1b which are screwed together with screws (not shown) and integrated. Have been. In the lower split mold 1, a circular or polygonal opening occupies most of the center. The opening 25 of the lower split mold 1 is surrounded by an annular groove 27 on the lower surface of the lower split mold 1. An annular clamp frame 31 formed of an elastic member such as silicon rubber and attached to a base 29 provided on the side of the compressed air device 17 is provided so as to surround immediately outside the annular groove 27. The upper portion of the clamp frame 31 presses the surplus portion of the plastic sheet against the lower surface of the lower split mold 1.

The base 29 is also provided with a spring-supported metal annular pressing member 33 which is in contact with the lower side of the edge of the opening 25, and extends along the entire periphery of the edge of the opening 25. Thus, the plastic sheet 21 is pressed against the lower surface of the lower split mold 1.

Further, the base 29 is provided with an annular male blade 35 so as to surround the opening 25, and the tip of the male blade 35 meshes with the annular groove 27 to form the plastic sheet 21. It is configured to cut the surplus part.

The upper split mold 3, the lower split mold 1 and the base 29 are provided with positioning holes 37 so as to penetrate them. At the time of assembling the apparatus for the first time, bolts 39 are passed through the upper split mold 3, the lower split mold 1 and the base 29, and the upper split mold 3, the lower split mold 1 and the base 29 are integrated into the positioning holes 37. By doing so, the mutual positional relationship can be easily adjusted. With the parts integrated with each other, the parts are mounted on the respective drive mechanisms, and then the bolts 39 are removed and the alignment of the apparatus for forming is completed (FIG. 39 shows the state before removal).

Separately, the lower split mold 1 is also provided with a guide hole 41, and the guide hole 41 is mounted on a stop block 43 provided on the base 29 and has a tapered tip. The rod 45 can be inserted. The lower split mold 1 and the base 29 are once positioned with respect to each other using the positioning holes 37 and fixed to the respective drive mechanisms, but the lower split mold 1 enters and exits the undercut portion in each molding process. The guide holes 41 and the positioning rods 45 are positioned so that the base 29 and the lower split mold 1 are precisely positioned again for each molding so that the annular male blade 35 is correctly engaged with the annular groove 27 at each molding. Help to make. On the other hand, the stop block 43 prevents the male blade 35 from colliding with the bottom of the annular groove 27 when cutting the surplus portion of the plastic sheet 21.

FIG. 6 shows the configuration of the base 29 and the components provided thereon. As shown somewhat exaggeratedly in the figure, the annular cutting edge 47 of the annular male blade 35 has an increasing or decreasing height along its circumference. In the figure, the height of the cutting edge 47 increases and decreases so as to draw a smooth curve, and four peaks and valleys are arranged at equal intervals over the entire circumference. However, the increase and decrease of the height of the cutting edge 47 may be linear in a side view as shown in FIG. 7, or may be uneven and have a step as shown in FIG.

[0042]

[Effect of the invention]

 The present invention can improve the yield in manufacturing a dome-shaped compressed air product having an undercut, and can reduce the weight and cost of the apparatus.

[Brief description of the drawings]

FIG. 1 is an elevation view including a cross-sectional view of the device of the present invention.

FIG. 2 is an elevational view including a cross-sectional view of the device in a state where a plastic sheet is clamped to a lower split mold.

FIG. 3 is an elevation view including a cross-sectional view of the apparatus in a state where a plastic sheet is being freely blown.

FIG. 4 is an elevational view including a cross-sectional view of the device in a state where the free blow dome is pushed out by the upper split mold.

FIG. 5 is a partial cross-sectional view of the apparatus showing a state in which a surplus sheet is being cut.

FIG. 6 is a cross-sectional view showing the transition of the height of the cutting edge along the circumference.

FIG. 7 is a cross-sectional view of another specific example showing transition of the height of the cutting edge along the circumference.

FIG. 8 is a cross-sectional view of a further specific example showing transition of the height of the cutting edge along the circumference.

[Explanation of symbols]

1 = Lower split type, 3 = Upper split type, 5 = Elevating shaft, 7 = Elevating frame, 9 = Female screw member, 11 = Outer frame, 13 = Central part, 15
= Elevating shaft, 17 = Pneumatic device, = 19 = Female screw member, 21
= Plastic sheet, 23 = molded product, 25 = opening,
27 = annular groove, 29 = base, 31 = clamp frame, 33 =
Annular pressing member, 35 = male blade, 37 = locating hole, 39
= Bolt, 41 = guide hole, 43 = stop block, 45
= Positioning rod

Claims (10)

[Utility model registration claims] 1. A pressure forming apparatus, comprising: (1) a lower split mold for forming an undercut portion having a clamp opening and a molding surface extending laterally from the clamp opening inside. The lower split mold composed of a plurality of partial split molds so as to be able to be split in the horizontal direction,
(2) a drive device for opening and closing the upper split mold in the vertical direction with respect to the lower split mold, the upper split mold having a flat dome-shaped forming surface inside; ,
(3) a drive device for horizontally moving each of the split molds constituting the lower split mold into and out of the undercut portion;
(4) a pressurizing device having a clamp frame capable of airtightly clamping the heat-softened plastic sheet on the lower surface of the lower split mold with respect to the periphery of the clamp opening from below. 5) Inside the clamp position by the clamp frame, an annular groove surrounding the clamp opening is provided on the lower surface of the lower split mold in contact with the plastic sheet, and (6) (a) the annular groove An annular male blade having a height which engages with the groove and cooperates with the groove to cut the sheet, but the cutting edge does not reach the plastic sheet even if the plastic sheet is clamped in an airtight manner. A male blade characterized in that the height of the blade edge increases and decreases along the circumference; (b)
The upper surface, which is located along the inside of the male blade, may protrude beyond the highest tip of the male blade, but does not hold down the plastic sheet during the formation of the plastic sheet by compressed air A metal annular pressing member arranged to be supported by a spring so as to be positioned at a height,
And (7) after the pneumatic forming, the pneumatic device is further pressed against the lower split mold so that the annular pressing member lowers the plastic sheet to the lower split mold lower surface. And a cutting device for sequentially cutting the plastic sheet by the male blade. 2. The apparatus of claim 1 wherein the height of the cutting edge of the male blade is increased or decreased to form a plurality of peaks and valleys along the circumference. 3. The apparatus of claim 2, wherein said plurality of peaks and valleys are evenly distributed along a circumference. 4. The apparatus according to claim 1, wherein the height of the cutting edge of the male blade has a step along the circumference consisting of at least one pair of convex portions and concave portions therebetween. Further, (7) a sensor for detecting that the apex of the free blow dome generated by free blowing the plastic sheet above the clamp opening has reached a predetermined height, and (8) A) air-in / out control device for air-locking the pneumatic device in response to a detection signal from the sensor, and accompanying drive control for operating the upper split mold and the lower split mold so as to clamp the mold; And (9) said air entry and exit control device and an integrated or separate air entry and exit control device for introducing compressed air into said mold after clamping. 4. The apparatus according to any of 4. 6. The apparatus according to claim 1, wherein said upper split mold is supported from above by a motor-driven supporting member at a central portion thereof so as to be able to ascend and descend. . 7. When the mold is mounted, the clamp frame is pressed against the lower split mold, and the compressed air device, the lower split mold and the upper split mold in a state where the clamps are clamped are positioned vertically so as to mutually position the correct horizontal positions. It is further characterized in that a positioning hole, which may be a bolt hole, which is provided in the direction from the upper split mold to the compressed air device through the lower split mold, is provided at least for each of the divided molds constituting the lower split mold. The apparatus according to any one of claims 1 to 6, wherein 8. The apparatus according to claim 1, further comprising a stopper provided between said lower mold and said compressed air device for preventing the cutting edge of said male blade from abutting against the bottom of said annular groove. ,
The device according to claim 1. 9. A guide for precisely positioning the annular groove of the lower split mold with respect to the male blade is provided between the lower split mold and the compressed air device. The apparatus according to any one of claims 1 to 8, further comprising: 10. The apparatus according to claim 9, wherein said guide comprises a positioning rod provided on said compressed air device side and a guide hole provided on said lower split mold.