JP4011048B2 - Vacuum forming equipment - Google Patents

Description

  The present invention relates to a vacuum forming apparatus that injects a molding material into a mold while the mold is clamped in an atmosphere evacuated to a desired degree of vacuum.

  2. Description of the Related Art Conventionally, various molding apparatuses for producing a molded product by injecting a molding material into a mold are known. For example, in the molding apparatus disclosed in Patent Document 1, the mold is exhausted to a desired degree of vacuum. A molded product is produced by injecting a molding material into a mold in a state where the mold is clamped. In such a conventional molding apparatus, since the inside of the mold is directly evacuated (evacuated) by a vacuum pump, a highly rigid mold capable of withstanding exhaust is used, and various sealing materials (for example, O A ring and an on-off valve) are separately provided in the mold, whereby the inside of the mold is maintained at a desired degree of vacuum.

  By the way, in the structure which exhausts the inside of a metal mold | die directly, it is necessary to provide separately various sealing materials as mentioned above in a metal mold | die, and since the effort and expense for that are separately added, the manufacturing cost of a shaping | molding apparatus will rise. In addition, since the mold used in the conventional molding apparatus is limited to one having high rigidity, it is necessary to select a mold material that achieves high rigidity. Therefore, a mold that can be applied to the molding apparatus. As a result, the manufacturing cost of the mold itself increases, and as a result, the manufacturing cost of the molding apparatus also increases. Further, when the inside of the mold is directly evacuated with a vacuum pump as in the conventional molding apparatus, it takes time to reach the desired degree of vacuum in the mold, so that the molding efficiency cannot be increased. It should be noted that a desired degree of vacuum cannot be obtained depending on the accuracy of the mold (for example, the accuracy of various sealing materials), and as a result, a molding defect may occur.

Therefore, instead of directly evacuating the inside of the mold, for example, the mold is placed in an atmosphere evacuated to a desired degree of vacuum, and the molding material is injected into the mold with the mold clamped. Configuration is conceivable. However, in such a configuration, a mold clamping unit (e.g., an upper and lower mold clamping structure, a lifting mechanism for the structure), an injection molding unit, and each of these units are provided in the exhaust chamber for maintaining a desired degree of vacuum. Various wirings for supplying power to the unit (for example, hot or cold runner oil wiring, mold heater wiring) must be accommodated in a lump. In this case, it is also necessary to consider a configuration for taking in and out the mold with respect to the exhaust chamber and a configuration for adjusting and maintaining the above units and various wirings. However, there is currently no known configuration that solves such a problem.
JP-A-11-70545

  The object of the present invention is to provide a molding efficiency capable of injecting a molding material into a mold in a state in which the mold is clamped in an atmosphere evacuated to a desired degree of vacuum regardless of the type and precision of the mold. It is to provide a high-priced and low-cost vacuum forming apparatus.

To achieve the above object, the present invention provides a vacuum molding apparatus is injected into the mold the molding material while clamping the mold in an atmosphere which is evacuated to a desired vacuum degree, gold An exhaust mold clamping unit having a storage chamber capable of storing a mold and an injection unit for injecting a molding material into a mold stored in the storage chamber are provided.
The exhaust mold clamping unit exhausts the storage chamber to a desired degree of vacuum and clamps the mold, and the exhaust mold clamping unit allows the mold to escape from the storage chamber at the time of demolding at least when the molded product is taken out from the mold. Insertion / removal mechanism for reinserting the mold after removing the molded product into the storage chamber, mold clamping mechanism for clamping the mold accommodated in the storage chamber, and power for driving these insertion / removal mechanism and mold clamping mechanism And a flexible holding body that collectively holds various wirings for supplying the wiring, and the flexible holding body is provided at a position that does not interfere with the insertion / removal mechanism and the mold clamping mechanism in the storage chamber, It moves back and forth following the operation of the insertion / removal mechanism, and moves up / down following the lifting / lowering operation of the mold clamping mechanism. In addition, the vacuum forming apparatus accommodates the mold by the insertion / removal mechanism when the molded product is removed. Escaped from the mold and took out the molded product from the mold Bali avoided shutter which the burr is prevented from entering the storage chamber when the blow off burrs scattered in and around the mold in the air is provided.

  According to the present invention, a molding efficiency capable of injecting a molding material into a mold in a state in which the mold is clamped in an atmosphere evacuated to a desired degree of vacuum regardless of the type and precision of the mold. High-priced and low-cost vacuum forming apparatus can be realized.

Hereinafter, a vacuum forming apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. The vacuum forming apparatus of the present embodiment can efficiently produce various molded products by injecting a molding material into the mold in a state where the mold is clamped in an atmosphere exhausted to a desired degree of vacuum. Can be done.
In order to realize such an effect, the vacuum forming apparatus has an exhaust chamber having an accommodating chamber 6 in which molds (upper mold 2 and lower mold 4) can be accommodated, as shown in FIGS. 1 (a) and 1 (b). A mold clamping unit 8 and an injection unit 10 for injecting a molding material into molds (upper and lower molds clamped) 2 and 4 accommodated in the storage chamber 6 are provided, and an exhaust mold clamping unit 8 ( Hereinafter, the evacuation unit 8 is simply evacuated to a desired degree of vacuum and clamped.

  The exhaust unit 8 includes, for example, an insertion / removal mechanism for inserting / removing a mold (for example, the lower mold 4) into / from the storage chamber 6, and a mold for clamping the molds 2, 4 stored in the storage chamber 6. A clamping mechanism and a flexible holder 12 that collectively holds various wires for supplying electric power for driving the insertion / removal mechanism and the mold clamping mechanism are provided. It moves back and forth following the operation of the detaching mechanism and moves up and down following the lifting and lowering operation of the mold clamping mechanism.

  The interior of the storage chamber 6 is hermetically sealed with respect to the outside, and a front opening / closing door 14 that opens and closes when the mold (lower mold 4) is inserted into and removed from the storage chamber 6, and an insertion / removal A rear opening / closing door 16 (see FIGS. 4A and 4B) is provided for various operations on various mechanisms held by the mechanism and the mold clamping mechanism and the flexible holder 12. In the storage chamber 6, the flexible holder 12 is provided at a position that does not interfere with the insertion / removal mechanism or the mold clamping mechanism.

  The front opening / closing door 14 has a closed position (see FIGS. 1 (a) and 2 (b)) in which the accommodation chamber 6 is hermetically sealed, and an open position (FIG. 1 (b)) in which the accommodation chamber 6 is opened to the outside. 2 (a)). As an example of a method for positioning the front opening / closing door 14 in such a positional relationship, in the present embodiment, the front opening / closing door 14 is configured to be slidable in the vertical directions J1 and J2 by an actuator 18. In this case, for example, a hydraulic cylinder can be applied as the actuator 18, and when the hydraulic cylinder 18 is extended upward, the front opening / closing door 14 is positioned at the closed position, while when the hydraulic cylinder 18 is pulled downward, the front opening / closing door is provided. 14 is positioned in the open position.

The front open / close door 14 has an upper slide member 20 and a lower slide member 22 fixed to the upper and lower positions on both sides of the front open / close door 14. The pair of lower slide members 22 engage with the upper side guide guide grooves 24 formed along the slide direction, and the pair of lower slide members 22 are formed on the both side walls of the lower portion of the exhaust unit 8 along the slide direction of the front opening / closing door 14. The guide guide groove 26 is engaged.
Thereby, for example, when the hydraulic cylinder 18 is extended upward from the state where the front opening / closing door 14 is positioned at the open position (see FIGS. 1B and 2A), the upper slide member 20 and the lower slide member 22 are moved. By moving upward while being guided by the upper side guide guide groove 24 and the lower side guide guide groove 26, the front opening / closing door 14 is stably and smoothly closed without causing blurring or fluctuation (FIG. 1A). And FIG. 2 (b)).

  Further, the upper side guide guide groove 24 and the lower side guide guide groove 26 have upper end sides 24a and 26a (see FIGS. 2A and 2B) curved toward the housing chamber 6. Therefore, the upper slide member 20 and the lower slide member 22 moved to the upper J1 along the upper side guide guide groove 24 and the lower side guide guide groove 26 are arranged in the accommodation chamber 6 direction K (FIG. 2) on the upper end sides 24a and 26a. (Refer to (b)). The front opening / closing door 14 also slides in the accommodation chamber 6 direction K following the movement change, so that the front opening / closing door 14 is pressed against the accommodation chamber 6 and the accommodation chamber 6 can be hermetically sealed. . In this case, in order to further improve the airtightness, an O-ring (rubber packing) (not shown) may be provided inside the front opening / closing door 14 (portion in pressure contact with the storage chamber 6).

  As shown in FIGS. 4A and 4B, the rear opening / closing door 16 is rotatably supported at one end side by a hinge (hinge) 28 and at the other end side by a fastening body (for example, a clip). 30 is provided. As a result, the rear opening / closing door 16 can be opened / closed around the hinge 28, and various operations (for example, maintenance) and flexible maintenance for the insertion / removal mechanism and the mold clamping mechanism can be performed from the back side of the storage chamber 6 in the opened state. Various operations (for example, an operation of connecting the outlet T) can be performed on various wirings held by the body 12. On the other hand, when closing, by fastening with the fastening body 30, the rear opening / closing door 16 can be brought into pressure contact with the storage chamber 16 and the storage chamber 6 can be hermetically sealed. In this case, in order to further improve the airtightness, an O-ring (rubber packing) 32 may be provided inside the rear opening / closing door 16 (the portion that is in pressure contact with the storage chamber 6). In addition, although the three hinges 28 and the fastening body 30 were shown in the drawing as an example, the number of hinges can be increased or decreased according to the size and weight of the rear opening / closing door 16 and the usage environment.

  As shown in FIGS. 1 and 2, the exhaust unit 8 is provided with a mounting board 34a for mounting a mold (lower mold 4) and a movable board 34b for supporting the mounting board. On the other hand, the mold (upper mold 2) is attached to the upper part of the storage chamber 6 via the attachment plate 36. The insertion / removal mechanism includes an insertion / removal mechanism that slidably supports the mounting board 34a when the mounting board 34a is inserted into / removed from the front chamber F1 and the rear F2 (see FIG. 2A). A linear motion guide device is provided, and the mold clamping mechanism is provided with an up / down linear motion guide device 38 that slidably supports the movable platen 34b when the movable platen 34b is moved up and down J1 and downward J2. It has been.

  The insertion / removal linear motion guide device is provided with a guide member 40 (see FIGS. 1B and 4B) for guiding the mounting board 34a to the front F1 and the rear F2. In the present embodiment, the guide members 40 are provided on both sides of the mounting board 34a, whereby the mounting board 34a can be stably and smoothly moved forward F1 with respect to the storage chamber 6 without being shaken or fluctuated. And it becomes possible to insert / remove to the rear F2 (see FIG. 2A).

  According to such an insertion / removal linear motion guide device, the mounting board 34a is moved to the front F1 in a state where the front opening / closing door 14 is positioned at the open position as shown in FIG. The mold (lower mold 4) can be pulled out of the storage chamber 6 together with the board 34a. On the other hand, the mold (lower mold 4) can be inserted into the storage chamber 6 together with the mounting board 34a by moving the mounting board 34a to the rear F2. Further, in a state where the mounting board 34a is completely inserted into the housing chamber 6, the mold (lower mold 4) is accurately positioned without any deviation just below the mold (upper mold 2). For this reason, it is not necessary to align the lower mold 4 and the upper mold 2 with the mold clamping mechanism, and the formation efficiency of the vacuum forming apparatus can be further increased.

  The linear motion guide device 38 for raising and lowering is provided with a high-rigidity linear guide 42 extending along the raising and lowering direction on both sides of the movable platen 34 b and a slider 44 that slides along the linear guide 42. (See FIG. 1B), the slider 44 is connected to the movable platen 34b through the absorber 46 (see FIG. 1C). More specifically, the movable platen 34 b is firmly supported by a highly rigid triangular truss structure 48, and the absorber 46 is interposed between the slider 44 and the vertical surface 48 a of the triangular truss structure 48. Has been. In this case, even if the movable platen 34a expands in the direction of arrow E due to thermal expansion, the absorber 46 elastically absorbs the expansion amount (minutes), so that the frictional resistance between the linear guide 42 and the slider 44 is increased. Can be prevented (the frictional resistance is always kept constant). As a result, the up-and-down operability in the up and down directions J1 and J2 of the movable platen 34b can always be maintained constant and in an optimum state. In addition, the absorber 46 can be comprised by elastic members, such as a disc spring and a compression spring, for example.

  According to such an elevating linear motion guide device 38, when the mounting board 34a is completely inserted into the storage chamber 6 (the initial storage state), the movable board 34b is moved upward J1 to move the mounting board 34a. At the same time, the mold (lower mold 4) moves upward J1, and the lower mold 4 and the upper mold 2 can be accurately pressed against each other. Then, by further moving (or finely moving) the movable platen 34b upward J1 from this state, the lower mold 4 and the upper mold 2 can be clamped with a desired force (see FIG. 2B). ). On the other hand, by moving the movable platen 34b downward J2, it is possible to position the mold (lower die 4) together with the mounting platen 34a in the housed initial state. Thus, by applying the high-rigidity linear guide 42 to the elevating linear motion guide device 38, the movable platen 34b can be raised and lowered stably and smoothly with high accuracy and without shaking.

As described above, the power for driving the insertion / removal mechanism (insertion / removal linear motion guide device) and the mold clamping mechanism (elevation linear motion guide device 38) is used for various power supply wirings (for example, oil for hot or cold runners). Wiring, wiring for mold heaters), when these various wirings are individually routed into the storage chamber 6, not only the routing configuration becomes complicated, but also various types of operations are performed during the operation of the insertion / removal mechanism and the mold clamping mechanism. The case where wiring and each mechanism interfere is assumed.
Therefore, in the present embodiment, the various wirings L are collectively held by the flexible holding body 12, and the flexible holding body 12 is provided at a position that does not interfere with the insertion / removal mechanism or the mold clamping mechanism. ing.

  For example, as shown in FIG. 2C, the flexible holding body 12 is configured by connecting a hollow cylindrical connecting member 12 a via a hinge H so as to be relatively rotatable, and the connecting member 12 a. Various wirings L can be inserted and held in the inside. Thereby, as shown in FIG. 2D, for example, even when each connecting member 12a is relatively rotated in the direction of the arrow, the various wirings L can be bent smoothly and without being scattered. The flexible holding body 12 is arranged so that the rotation direction of each connecting member 12a follows the operation of the insertion / removal mechanism or the mold clamping mechanism and does not interfere with the insertion / removal mechanism or the mold clamping mechanism.

  According to such a configuration, the flexible holding body 12 and each mechanism do not interfere with each other during the operation of the insertion / removal mechanism or the mold clamping mechanism, so that it is possible to follow the front F1 operation and the rear F2 operation of the insertion / removal mechanism. The flexible holding body 12 can be moved back and forth smoothly, and the flexible holding body 12 can be raised and lowered smoothly following the upward and downward movements of the mold clamping mechanism to the upper J1 and the lower J2.

  Further, in the vacuum forming apparatus of the present embodiment, as described above, the lower mold 4 and the upper mold 2 are clamped with the linear motion guide device 38 for raising and lowering the mold clamping mechanism (FIG. 2B). The housing chamber 6 is evacuated to a desired degree of vacuum by the exhaust unit 8, and the molding material is injected from the injection unit 10 into the molds (upper and lower molds clamped) 2 and 4 in this state. In addition, as a molding material, resin, rubber | gum, etc. can be assumed, for example.

For example, as shown in FIG. 1 (d), the exhaust unit 8 is provided with a vacuum tank 50 connected to the storage chamber 6 and a vacuum pump 52 that exhausts the inside of the vacuum tank 50 to a predetermined degree of vacuum. Thus, the storage chamber 6 can be evacuated to a desired degree of vacuum in a short time by pulling the vacuum tank 50 to a negative pressure.
In this case, the vacuum pump 52 may be directly connected to the storage chamber 6, but in that case, it takes time to exhaust the storage chamber 6 to a desired degree of vacuum, which is not efficient. In contrast, in the configuration in which the vacuum pump 52 is connected to the storage chamber 6 via the vacuum tank 50, the storage chamber 6 can be exhausted in a short time due to the negative pressure action of the vacuum tank 50. Specifically, the vacuum tank 50 is evacuated in advance, and after the accommodation chamber 6 is airtight, the accommodation chamber 6 and the vacuum tank 50 are first connected to exhaust the accommodation chamber 6 at a stretch, and then the vacuum pump 52 and the accommodation chamber. By connecting only 6 and increasing the degree of vacuum, the storage chamber 6 can be exhausted in a short time.

Here, for example, five vacuum pumps 52 having an exhaust speed of 4166 liters / minute are prepared, and four types of vacuum tanks 50 having capacity types of 1000 liters, 1200 liters, 1300 liters, and 1500 liters are prepared. Then, for example, the time required until the degree of vacuum in the 500 liter storage chamber 6 reaches 20 Torr is compared. Note that 1 Torr = 133.32 Pa, 1 atmosphere = 1013 hPa = 760 Torr = 760 mmHg.
29 seconds when the vacuum pump 52 is directly connected to the storage chamber 6, 20 seconds when the 1000 liter vacuum tank 50 is used, 19 seconds when the 1200 liter vacuum tank 50 is used, and 1300 liter vacuum tank 50 The required time of 18.6 seconds was obtained when using 1 and 7 seconds were obtained when using a 1500 liter vacuum tank 50.

  As a result, it has been clarified that the storage chamber 6 can be evacuated to a desired degree of vacuum in a shorter time when the vacuum tank 50 is interposed as compared with the case where the vacuum pump 52 is directly connected to the storage chamber 6. . In this case, it is possible to further shorten the time required to reach the degree of vacuum by increasing the capacity of the vacuum tank 50. In addition, the combination of the vacuum tank 50 and the vacuum pump 52 mentioned here is an example, and can be arbitrarily combined according to the capacity | capacitance of the storage chamber 6, the use purpose or use environment of a vacuum forming apparatus. Moreover, the capacity | capacitance of the vacuum tank 50 can also select arbitrary types.

Thus, a desired molded product can be produced by injecting the molding material from the injection unit 10 into the molds 2 and 4 in a state where the storage chamber 6 is evacuated to a desired degree of vacuum. When the molded product is removed, the mold (lower mold 4) can be pulled out of the storage chamber 6 by the insertion / removal mechanism, and the molded product can be taken out from the mold.
Thereafter, an operation of blowing off burrs scattered in and around the mold (lower mold 4) with air is performed. When the burrs enter the storage chamber 6 at that time, burrs are generated in the next molding process. The mold may not be opened due to being mixed into the molded product, or the operation of the insertion / removal mechanism or the mold clamping mechanism may be defective.

  Therefore, the vacuum forming apparatus of the present embodiment is provided with a burr avoiding shutter 54 that prevents such a situation. As shown in FIGS. 3 (a) and 3 (b), the burr avoiding shutter 54 is supported, for example, by an air cylinder 56 so as to be movable up and down, and when the burrs scattered in and around the lower mold 4 are blown off with air. By lowering the burr avoiding shutter 54 to a position where the storage chamber 6 is shielded, it is possible to prevent the burr blown off by the air from entering the storage chamber 6.

  In addition to the various effects as described above, the vacuum forming apparatus of the present embodiment further accommodates the entire molds 2 and 4 in the storage chamber 6 that is evacuated to a desired degree of vacuum. Therefore, the molds 2 and 4 can be evacuated to a desired degree of vacuum regardless of the type of mold. Specifically, in the configuration in which the molds 2 and 4 are exhausted, various sealing materials (O-rings and on-off valves) are required separately, which complicates the mold structure and manufactures the molds. Costs will also increase. Furthermore, depending on the accuracy of the mold (accuracy of various sealing materials), a desired degree of vacuum cannot be obtained, and as a result, a molding defect may occur. However, as in this embodiment, the molds 2 and 4 are placed in an atmosphere evacuated to a desired degree of vacuum, and the molding material is injected with the molds 2 and 4 clamped. Thus, the mold structure can be simplified, and the manufacturing cost can be kept low.

Further, when the injection unit 10 is not used, the vacuum forming apparatus according to the present embodiment can be used as a vacuum press machine by simply closing the injection port (not shown) of the molding material. In addition, it is possible to provide a vacuum forming apparatus excellent in versatility.
Furthermore, in the conventional molding technique, the molding device (injection unit 10), the mold clamping device (lifting linear motion guide device 38), and the like are separately arranged and configured. However, in the vacuum molding device of the present embodiment, By integrating these, it becomes possible to dramatically improve the manufacturing efficiency of the molded product.

  In the above-described embodiment, the configuration in which the storage chamber 6 is evacuated to a desired degree of vacuum while the lower mold 4 and the upper mold 2 are clamped has been described. The lower mold 4 and the upper mold 2 may be clamped.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the vacuum forming apparatus which concerns on one embodiment of this invention, Comprising: (a) is a front view of the state which closed the front opening / closing door, (b) is the state of opening the front opening / closing door. Front view, (c) is an enlarged view of a linear motion guide device for raising and lowering a mold clamping mechanism, and (d) is an arrangement configuration diagram of a vacuum tank and a vacuum pump. (a) is a side view showing a state in which the flexible holding body moves back and forth following the operation of the insertion / removal mechanism, and (b) is a diagram showing the state where the flexible holding body follows the lifting / lowering operation of the mold clamping mechanism. The side view which shows the state which raises / lowers, (c) And (d) is a perspective view which shows the state in which each connection member of a flexible holding body rotates relatively. (a) is a side view showing a state where the burr avoiding shutter is lowered to a position where it shields the storage chamber, and (b) is a front view showing a state where the burr avoiding shutter is lowered to a position where it shields the accommodation chamber. (a) is a rear view which shows the state which closed the rear surface door, (b) is a rear view which shows the state which opened the rear surface door.

Explanation of symbols

2,4 Mold 6 Accommodating chamber 8 Exhaust unit 10 Injection unit 12 Flexible holder 14 Front open / close door 16 Rear open / close door

Claims (7)

A vacuum forming apparatus for injecting a molding material into a mold in a state where the mold is clamped in an atmosphere evacuated to a desired degree of vacuum,
An exhaust mold clamping unit having a storage chamber capable of storing a mold;
An injection unit for injecting a molding material into a mold housed in the housing chamber,
The exhaust mold clamping unit exhausts the storage chamber to a desired degree of vacuum and clamps the mold,
The exhaust mold clamping unit includes at least an insertion / removal mechanism that allows the mold to be removed from the storage chamber at the time of demolding to remove the molded product from the mold, and the mold after the molded product is removed is inserted into the storage chamber again . A mold clamping mechanism for clamping a mold housed in the storage chamber and a flexible holder for collectively holding various wirings for supplying electric power for driving the insertion / removal mechanism and the mold clamping mechanism are provided. And
The flexible holder is provided at a position that does not interfere with the insertion / removal mechanism and the mold clamping mechanism in the storage chamber, and moves back and forth following the operation of the insertion / removal mechanism, and also moves up and down following the lifting / lowering operation of the mold clamping mechanism. And
Further, in the vacuum forming apparatus, when the molded product is removed, the mold is removed from the storage chamber by the insertion / removal mechanism, and the molded product is taken out from the mold, and then the burrs scattered in and around the mold are aired. A vacuum forming apparatus characterized by being provided with a burr avoiding shutter for preventing the burr from entering the housing chamber when blown off by a vacuum. The interior of the exhaust mold clamping unit is hermetically sealed with respect to the outside. The front opening / closing door that opens and closes when the mold is inserted into and removed from the storage chamber, the insertion / removal mechanism, and the mold clamping The vacuum forming apparatus according to claim 1, further comprising a rear opening / closing door for various operations on various wirings held by the mechanism and the flexible holding body. The exhaust mold clamping unit includes a mounting board on which a mold is mounted and a movable board that supports the mounting board.
The insertion / removal mechanism is provided with an insertion / removal linear motion guide device that slidably supports the mounting board when the mounting board is inserted into / removed from the storage chamber. When moving up and down, there is provided a linear motion guide device for lifting to support the movable plate slidably,
The linear motion guide device for raising and lowering the mold clamping mechanism is provided with an absorber that elastically absorbs the thermal expansion when the movable plate thermally expands and maintains the movable operation of the movable plate constant. The vacuum forming apparatus according to claim 1 or 2, wherein:   The elevating linear motion guide device is provided with a linear guide that extends along the elevating direction of the movable platen and a slider that slides along the linear guide. The slider is movable through the absorber. The vacuum forming apparatus according to claim 3, wherein the vacuum forming apparatus is connected to the vacuum forming apparatus.   The vacuum forming apparatus according to claim 3, wherein the absorber is made of an elastic member.   The vacuum forming apparatus according to claim 5, wherein the elastic member includes at least a disc spring and a compression spring. The exhaust mold clamping unit is provided with a vacuum tank connected to the storage chamber and a vacuum pump for exhausting the inside of the vacuum tank to a predetermined vacuum level. By pulling the vacuum tank to a negative pressure, the storage chamber is opened. The vacuum forming apparatus according to claim 1, wherein the vacuum forming apparatus is evacuated to a desired degree of vacuum.

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