CN214687771U - Die and injection molding machine for producing orthodontic diaphragm - Google Patents

Abstract

The utility model relates to a mould and injection molding machine for producing just abnormal diaphragm, wherein, this mould includes cover half and movable mould, and the movable mould can move towards the cover half in order to inject the die cavity that is used for shaping just abnormal diaphragm with the cover half joint, and wherein, one in cover half and the movable mould has the outstanding wall that sets up around the die cavity, and another one in cover half and the movable mould has the concave part that is used for accepting the outstanding wall, and this concave part mutually supports with outstanding wall when movable mould and cover half joint in order to seal the die cavity under predetermined incomplete compound die state. The utility model discloses make just abnormal diaphragm can produce through the method of the extrusion of moulding plastics, just abnormal diaphragm yields of production is high, the waste material is few, the internal stress is little and even.

Description

Die and injection molding machine for producing orthodontic diaphragm

Technical Field

The utility model relates to a mould and injection molding machine for producing just abnormal diaphragm.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

The orthodontic diaphragm is also called as orthodontic diaphragm, dental diaphragm and the like, and is mainly used for manufacturing orthodontic braces. At present, the orthodontic diaphragm is mainly dependent on foreign suppliers, the orthodontic diaphragm used by domestic orthodontic solution suppliers is mainly purchased through foreign countries, and the orthodontic diaphragm does not have the production capacity of the orthodontic diaphragm. Therefore, orthodontic film procurement costs are high, and a great economic burden is imposed on orthodontic solution suppliers. The localization of orthodontic films is certainly a future development trend.

Currently, orthodontic diaphragms are produced by using an extrusion molding process, the produced sheet is cut into various shapes matched with orthodontic braces molding equipment, and then orthodontic braces of specific customers are customized by the orthodontic braces molding equipment. The cutting process can produce a lot of scrap, which virtually increases the material cost and the environmental pressure.

The extrusion molding process adopted for manufacturing the orthodontic diaphragm has high requirements on extrusion equipment, special extrusion molding equipment is needed, the equipment has large early investment (more than 1000 ten thousand RMB), the technical threshold is high, the internal stress of the produced product is difficult to control uniformly, the yield is low, and the cost is high. In addition, at present, no mature extrusion equipment suppliers exist in China, and if the extrusion equipment needs to be produced by the extrusion equipment suppliers, the extrusion equipment is completely dependent on import.

The existing injection molding process is a mature process, and the technical threshold is relatively low. The common injection molding only depends on single injection molding action to finish the processing of products, but the thickness of the orthodontic diaphragm is usually 0.5mm to 1mm, the products are very thin, the dies are difficult to be saturated during the injection molding, and the yield is extremely low; and because the wall thickness of the product is very thin, the product needs very large die cavity pressure during injection molding, and the pressure is maintained for a period of time, so that the product produced by injection molding also has very large internal stress, and the internal stress is maximum near a glue opening and is obviously reduced the farther away from the glue opening, which causes obvious internal stress unevenness. In the process of heating and forming the orthodontic braces, the local deformation of the orthodontic diaphragm is easily caused by the uneven distribution of internal stress, and finally the uneven distribution of the wall thickness of the orthodontic braces is caused, so that the orthodontic braces cannot be normally used for producing the orthodontic braces.

Therefore, it is desirable to provide a mold and an injection molding machine to produce orthodontic films by injection molding, and particularly to avoid the problems of difficult mold filling, high internal stress and uneven internal stress distribution of orthodontic films in the conventional injection molding method, so as to produce finished orthodontic films with excellent performance, thereby breaking through the technical barrier and greatly reducing the production cost.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a main objective is through the extrusion of moulding plastics production just abnormal diaphragm for just abnormal diaphragm of production has higher yields, less internal stress, and the internal stress distribution is even.

To this end, the present invention provides a mould for producing an orthodontic diaphragm by an injection extrusion method, the mould comprising a movable mould and a stationary mould, the movable mould being movable towards the stationary mould to engage with the stationary mould to define a cavity for moulding the orthodontic diaphragm, wherein one of the stationary mould and the movable mould has a projecting wall disposed around the cavity, and the other of the stationary mould and the movable mould has a recess for receiving the projecting wall, the recess and the projecting wall cooperating to seal the cavity in a predetermined non-fully closed condition when the movable mould is engaged with the stationary mould.

The preset incomplete mold closing state refers to a state when the distance between the movable mold and the fixed mold, particularly the distance between the movable mold base surface of the movable mold and the fixed mold base surface of the fixed mold reaches a preset distance and the sizing material starts to be injected; accordingly, the fully clamped state referred to herein is a state in which the movable mold is fully engaged with the stationary mold, particularly when the distance between the movable mold base surface of the movable mold and the stationary mold base surface of the stationary mold is zero.

The thickness of a cavity formed between the movable mold and the fixed mold in a preset incomplete mold closing state is larger than that of the cavity formed between the movable mold and the fixed mold in a complete mold closing state, and if rubber materials are injected into the cavity at the moment, the pressure required by the rubber materials during diffusion can be greatly reduced due to the increase of the thickness of the cavity under the condition that the thickness of an injection molding product is very thin, so that the internal stress of the orthodontic diaphragm formed after the rubber materials are solidified is reduced.

In addition, the sealed cavity can effectively prevent the glue from overflowing out of the cavity when the glue is injected in a preset incomplete die assembly state, so that the defect of a product caused by insufficient glue amount of the orthodontic diaphragm is avoided. In addition, the protruding wall limits the size of the cavity and avoids the phenomenon of uneven filling.

Preferably, the protruding wall is provided on the movable mold, and the recess is provided on the fixed mold.

Preferably, the stationary mold has an intermediate portion inside the recess for defining the cavity, the intermediate portion being flush with the stationary mold base surface of the stationary mold, and the movable mold has a central depression inside the projecting wall for defining the cavity, the central depression being depressed with respect to the movable mold base surface of the movable mold.

Preferably, the inner side wall of the projecting wall extends parallel to the moving direction of the movable mold, and correspondingly, the inner side wall of the recess also extends parallel to the moving direction of the movable mold, thereby avoiding the generation of flash and flash at the parting surface during the injection molding and extrusion.

Preferably, the outer side wall of the projecting wall is inclined with respect to the moving direction of the movable mold so that the projecting wall is tapered in the projecting direction of the projecting wall, and correspondingly, the outer side wall of the recess is inclined with respect to the moving direction of the movable mold so that the recess is tapered in the recessed direction of the recess, so that the projecting wall is less likely to collide with the mold when engaged with the recess.

Optionally, the protruding wall is provided with a first discontinuity and the recess is provided with a second discontinuity, the first and second discontinuities forming a flash area when the movable die is engaged with the fixed die to accommodate excess glue, thereby ensuring that the thickness of the formed orthodontic film is not affected by fluctuations in the amount of injected glue.

Preferably, the mould comprises a hot runner system adapted to inject the mould cavity with glue, provided with a needle valve adapted to close a glue injection opening of the mould for injecting glue, and hydraulic means adapted to control the movement of the needle valve and to keep the needle valve in position. The hot runner system helps to avoid the generation of the glue port and realizes the control of the opening and closing of the glue injection port.

In addition, the glue injection port is sealed by the hot runner system, so that backflow of injected glue can be avoided under the condition of not performing a 'pressure maintaining' process necessary in conventional injection molding, and product defects caused by insufficient glue amount are further prevented. In addition, a pressure maintaining process is cancelled, so that the stress on the rubber material at the rubber injection port is no longer higher than the stress on the rubber material at other parts of the product, the stress on each part of the product is uniform, and the orthodontic membrane with uniform internal stress is finally formed.

The present invention also provides an injection molding machine for producing orthodontic membranes by an injection molding extrusion method, wherein the injection molding machine is adapted to carry out the injection molding extrusion method as described above, or the injection molding machine comprises a computer readable medium or a mold as described above.

Therefore, the utility model provides a mould and injection molding machine make the orthodontic diaphragm of very thin thickness can make through the method of moulding plastics, have reduced the technical threshold of orthodontic diaphragm production, make its localization become possible to can also have following advantage:

1. compared with the orthodontic diaphragm produced by an extrusion process, the orthodontic diaphragm is formed in one step by injection molding, so that the generation of waste materials is reduced, and the environmental pressure caused by the waste materials is reduced.

2. The whole cavity is easily filled with the rubber material, and the internal stress is reduced.

3. The internal stress is distributed evenly, so that the subsequent orthodontic braces can be formed stably.

4. The wall thickness of the product can be precisely controlled.

5. The generation of flash and sprue is avoided.

6. The phenomenon of uneven filling is avoided.

7. Avoid appearance defects such as scratch, deformation and the like caused by the mechanical ejection process.

Drawings

The above features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings. The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The figures are not necessarily to scale, some features may be exaggerated or minimized to show details of particular components. In the drawings:

fig. 1 is a schematic side view of an injection molding machine for producing orthodontic films according to the present invention;

fig. 2 is a front view of a movable mold in an injection mold for producing an orthodontic diaphragm according to the present invention;

fig. 3 is a front view of a stationary mold in an injection mold for producing an orthodontic diaphragm according to the present invention;

fig. 4 is a side view of an injection mold for producing orthodontic membranes according to the present invention in a predetermined incomplete closing condition;

fig. 5 is an enlarged side view of an injection mold for producing orthodontic membranes according to the present invention in a predetermined incomplete mold closing state;

fig. 6 is a side view of an injection mold for producing orthodontic diaphragms according to the present invention in a fully closed state;

fig. 7 is an enlarged side view of an injection mold for producing orthodontic diaphragms according to the present invention in a fully closed state; and

fig. 8a and 8b are front and side views, respectively, of an orthodontic film produced according to the invention.

Detailed Description

Fig. 1 shows a schematic side view of an injection molding machine 1 for producing orthodontic films according to the invention, wherein the injection molding machine 1 comprises an injection unit 10 for injecting glue and a clamping unit 20 for clamping a mold 21. The mold 21 in fig. 1 is only for illustration, and its specific structure will be shown in detail in fig. 2 to 7.

The injection unit 10 comprises a hopper 11, which hopper 11 is connected to a barrel 12 having a cylindrical shape, and heating elements 13 are provided on the walls of the barrel 12, the heating elements 13 being used to heat the barrel 12 so that the solid raw material entering the barrel 12 from the hopper 11 is melted into a molten compound having fluidity. The interior of the barrel 12 accommodates a reciprocating feed screw 14, which feed screw 14 is driven by a drive mechanism consisting of an electric motor 15 and a transmission 16 to push the glue to the end of the barrel 12 close to the clamping unit 20, where after a certain amount of glue has been accumulated, the rotation of the feed screw 14 is stopped, and the feed screw 14 and the glue are pushed in the direction of the clamping unit 20 by means of a screw actuator 17, preferably driven by a hydraulic cylinder, provided at the end of the feed screw 14 remote from the clamping unit 20, whereby the glue is injected into the cavity of the mould 21 via an injection nozzle 18. Furthermore, the feed screw 14 is provided with a non-return valve 19 at one end close to the clamping unit 20, which non-return valve 19 eventually abuts against the inner wall of the barrel 12 to form a seal when the feed screw 14 is pushed towards the clamping unit, thereby preventing the glue that has been injected into the mould cavity from flowing back.

The clamping unit 20 is used to clamp together or separate a fixed mold 22 and a movable mold 23 constituting a mold 21, wherein the fixed mold 22 is mounted on a fixed plate 24 of the clamping unit 20, and the movable mold 23 is mounted on a movable plate 25 of the clamping unit 20. Furthermore, the fixing plate 24 is fixedly mounted on the base so as to remain stationary in operation; and the movable plate 25 is movably mounted on a tie rod 26 and is reciprocated along the tie rod 26 away from or toward the fixed plate 24 by being pushed by a mold actuating device 27, preferably driven by a hydraulic cylinder, provided on the side of the movable plate 25 opposite to the movable mold 23, thereby effecting opening and closing of the mold 21.

Fig. 2 shows a front view of the movable mold 23 for producing an orthodontic membrane according to the present invention, wherein the movable mold 23 has a movable mold base surface 230, also referred to as a parting surface, a central depression 231 recessed into the movable mold base surface 230, and a protruding wall 232 protruding from the movable mold base surface 230. The central depression 231 forms a cavity. The protruding wall 232 is provided around the edge of the central recessed portion 231, and the protruding wall 232 may be further provided with a first discontinuity 233 communicating with the central recessed portion 231, the first discontinuity 233 being slightly recessed in the movable mold base surface 230, but the recessed depth of the first discontinuity 233 is smaller than that of the central recessed portion 231. The recessed portion of the first discontinuity 233 is intended to form a flash for accommodating a small amount of overflow of glue in the mould cavity. In addition, an air outlet 234 is further disposed at the center of the central recess 231, and the air outlet 234 can blow air outwards through an external air source (not shown), so that the orthodontic film formed in the die cavity is ejected out of the die cavity, and traceless demolding is realized.

Fig. 3 shows a front view of the stationary die 22 for producing an orthodontic film of the present invention, wherein the stationary die 22 has a stationary die base surface 220 also referred to as a parting surface, a middle portion 221 flush with the stationary die base surface 220, and a recess 222 recessed into the stationary die base surface 220. The recess 222 is for receiving the protruding wall 232 of the movable mold 23, and the recess 222 forms a seal with the protruding wall 232 at the joint on the inner side when receiving the protruding wall 232 of the movable mold 23, so that the sizing material in the cavity does not leak in a predetermined incomplete mold clamping state. Here, the predetermined incomplete mold clamping state refers to a state in which the movable mold 23 moves toward the stationary mold 22 until the movable mold base surface 230 reaches a predetermined distance from the stationary mold base surface 220, in which state the protruding wall 232 and the recess 222 are engaged but the movable mold base surface 230 and the stationary mold base surface 220 are not engaged. Further, the recess 222 may be further provided with a second interruption 223 corresponding to the first interruption 233 of the movable mold 23, the second interruption 223 being interrupted by the recess 222, and the second interruption 223 being preferably flush with the fixed mold base surface 220 and the intermediate portion 221 for easy processing. The second breaking portion 223 may also protrude from the stationary mold base surface 220. In addition, a glue inlet 224 is further formed in the center of the middle portion 221, and glue enters a cavity between the fixed die 22 and the movable die 23 through the glue inlet 224.

Those skilled in the art will readily appreciate that the central depression 231 may be provided on the stationary mold 22 and the middle part 221 may be correspondingly provided on the movable mold 23, and that the heights/depths of the central depression 231 and the middle part 221 with respect to the respective base surfaces may also be correspondingly changed. Likewise, the protruding wall 232 and the recess 222, as well as the first and second discontinuities 233, 223 can also vary in location and height/depth accordingly. It is important that the junction of the projecting wall 232 and the recess 222 be capable of sealing the cavity in the predetermined incompletely clamped state, so that the mold 21 can be injected in the predetermined incompletely clamped state.

Fig. 4 and 5 show a side view and an enlarged view of an injection mold 21 for producing orthodontic membranes according to the invention in a predetermined incomplete closing condition. In a predetermined, non-fully clamped condition, the recess 222 receives the projecting wall 232 and forms the sealing surface 210, and the injection unit 10 now injects glue into the cavity sealed by the sealing surface 210. It is to be noted that, since the mold 21 is not closed, the thickness of the cavity is greater than the thickness of the orthodontic film to be formed, and therefore, the glue can be more easily diffused in the cavity at this time.

When a predetermined amount of glue is injected into the cavity, the cavity is partially filled, at which point, as described above, the check valve 19 of the feed screw 14 forms a seal against the inner wall of the barrel 12 to prevent backflow of glue from the cavity, so that full mold closure can be achieved by the urging of the mold actuator 27.

The mold 21 further comprises, by way of example and not limitation, a hot runner system 180, through which the glue injected from the injection nozzle 18 is injected into the cavity between the stationary mold 22 fixed to the stationary plate 24 and the movable mold 23 fixed to the movable plate 25. The hot runner system 180 may include a needle valve 181 and a hydraulic ram 182, the needle valve 181 closing the compound injection port 224 of the fixed mold 22 under the urging of the hydraulic ram 182 to further prevent backflow of the compound in the mold cavity. Hot runner system 180 may also be implemented separately to prevent backflow of the compound in the mold cavity.

Further, as can be clearly seen in fig. 4 and 5, the inner side wall of the projecting wall 232 extends parallel to the moving direction of the movable mold 23, and correspondingly, the inner side wall of the recess 222 also extends parallel to this direction, so that a tight joint is formed when the two inner side walls are joined to avoid the generation of flash and flash at the parting surface during the injection molding and extrusion. In contrast, the outer side wall of the protruding wall 232 is inclined with respect to the moving direction of the movable mold 23 so that the protruding wall 232 is tapered in the protruding direction, and correspondingly, the outer side wall of the recess 222 is inclined with respect to the moving direction of the movable mold 23 so that the recess 222 is tapered in the recessed direction, thereby avoiding the protruding wall 232 and the recess 222 from colliding with each other at the time of engagement.

Fig. 6 and 7 show a side view of an injection mold 21 for producing orthodontic membranes according to the invention in a fully closed state and its enlarged view. In the process from the preset incomplete mold closing state to the complete mold closing state, as the backflow of the sizing material is blocked, the sizing material is further diffused in the direction away from the glue injection port 224 along with the continuous compression of the thickness of the mold cavity until the mold cavity is filled with the sizing material when the complete mold closing state is reached. If there is excess gum, it will overflow into the flash area. And then cooling the glue in the cavity to form the orthodontic diaphragm.

After the orthodontic film is formed, the movable die 23 is driven to open the die 21 by the reverse actuation of the die actuating device 27 until the fully opened state (not shown) of the die 21 is reached, and the air is blown from the air blowing port 234 to the formed orthodontic film through an external air source (not shown) so as to blow the orthodontic film out of the die cavity without generating ejection impressions.

The injection molding process of the orthodontic film in the injection molding machine is further described below with reference to specific embodiments.

Example one

The injection molding machine and the mold of the utility model are used for injection molding of the orthodontic diaphragm with the diameter D of 125mm and the thickness H of 0.75mm in the figures 8a and 8 b. Preferably, a computer-readable medium is provided in the injection molding machine, the computer-readable medium storing a program that, when executed, controls the injection extrusion method.

The mold uses a single-point needle valve hot runner system 180, the head of a needle valve 181 is flush with the surface of a product, and the opening and closing of the needle valve 181 are controlled by a hydraulic oil cylinder 182, so that the needle valve 181 can resist the pressure in the mold cavity, and the needle valve 181 is prevented from shifting. The edge of the cavity is designed to be penetrated, that is, the protruding wall 232 of the movable mold 23 is 3mm higher than the surface of the cavity to be inserted into the concave part 222 of the fixed mold 22 and at least closely fit inside to form a seal in a predetermined incomplete mold closing state, so that flash and flash on the mold parting surface during injection molding and extrusion are avoided. Four flash areas formed by the first discontinuous portions 233 and the second discontinuous portions 223 are arranged at the edges of the cavity, the thickness of the flash areas is 0.1mm, excessive rubber materials in the injection molding and extrusion process can be discharged from the flash areas, and therefore the wall thickness of a product is guaranteed.

The detailed injection molding process of the orthodontic film is as follows.

The method comprises the steps of installing a die 21 of an orthodontic diaphragm on an injection molding machine with an injection molding extrusion function, connecting a water path, a hot runner control oil path and a gas cap gas path, setting the mold locking force of the injection molding machine to be 150 tons, setting the temperature of a charging barrel to be 270 ℃, setting the temperature of the die to be 80 ℃, setting the rotating speed of a screw to be 0.1 m/min, measuring the glue amount to be 12 cubic centimeters, and setting the preset incomplete mold closing state to be that the distance between a moving mold base plane 230 and a fixed mold base plane 220 is 0.5mm, and setting the injection glue amount to be 9.8 cubic centimeters.

Thermoplastic transparent nylon material Grilamid TR90 is poured into a feed hopper 11 of the injection molding machine, the amount of 12 cubic centimeters of glue is measured, and the movable mold is moved towards the fixed mold until a preset incomplete mold closing state is achieved, namely the distance between the movable mold base surface 230 and the fixed mold base surface 220 is 0.5 mm. The distance between the movable mold base surface 230 and the stationary mold base surface 220 can be measured by a conventional distance sensor to confirm whether the mold is in a predetermined incomplete mold clamping condition. When the control unit of the injection molding machine, which includes the computer readable medium and runs the control program therein, receives the seating signal, the moving mold 23 is stopped and the needle valve 181 opens the glue injection opening 224, and at the same time, the injection unit 10 starts to inject glue. When the injected rubber reaches 9.8 cubic centimeters and the cavity is not filled, the needle valve 181 closes the rubber injection port 224, and the injection unit starts the metering action. At this time, the mold locking is synchronously opened, that is, the movable mold 23 is pushed by the mold actuating device 27 to further move towards the fixed mold 22, so that the molten rubber in the cavity is extruded until the cavity is filled, a complete mold locking state is achieved, and the mold locking force reaches 150 tons. The fully clamped state was maintained for 5 seconds, at which time the molten compound in the cavity was cooled and formed. Thereafter, the mold 21 is opened to a designated position, that is, the mold 21 reaches a fully opened state, and the air supply is turned on to blow air from the air blowing port 234 to release the product. So far, the injection molding and extrusion molding process of the orthodontic diaphragm is completed.

Example two

The injection molding machine and the mold of the utility model are used for injection molding of the orthodontic diaphragm with the diameter D of 125mm and the thickness H of 0.75mm in the figures 8a and 8 b. Preferably, a computer-readable medium is provided in the injection molding machine, the computer-readable medium storing a program that, when executed, controls the injection extrusion method.

The design of the mold is the same as that of the first embodiment, and the description thereof is omitted.

The detailed injection molding process of the orthodontic film is as follows.

The method comprises the steps of installing a die 21 of an orthodontic diaphragm on an injection molding machine with an injection molding extrusion function, connecting a water path, a hot runner control oil path and a gas cap gas path, setting the mold locking force of the injection molding machine to be 150 tons, setting the temperature of a charging barrel to be 270 ℃, setting the temperature of the die to be 80 ℃, setting the rotating speed of a screw to be 0.1 m/min, measuring the glue amount to be 12 cubic centimeters, and setting the preset incomplete mold closing state to be that the distance between a moving mold base plane 230 and a fixed mold base plane 220 is 1mm, and setting the injection glue amount to be 9.8 cubic centimeters.

Thermoplastic transparent nylon material Grilamid TR90 was poured into a hopper 11 of an injection molding machine, and an amount of 12 cubic centimeters of glue was measured to move the movable mold toward the stationary mold until a predetermined incomplete mold clamping state was reached, i.e., a distance of 1mm between the movable mold base surface 230 and the stationary mold base surface 220. The distance between the movable mold base surface 230 and the stationary mold base surface 220 can be measured by a conventional distance sensor to confirm whether the mold is in a predetermined incomplete mold clamping condition. When the control unit of the injection molding machine, which includes the computer readable medium and runs the control program therein, receives the seating signal, the moving mold 23 is stopped and the needle valve 181 opens the glue injection opening 224, and at the same time, the injection unit 10 starts to inject glue. When the injected rubber reaches 5 cubic centimeters, the cavity is not filled, and the needle valve 181 still opens the rubber injection port 224. Then, the movable mold 23 is pushed by the mold actuating device 27 to move further towards the fixed mold 22, and simultaneously the screw actuating device 17 continues to push the screw to move towards the clamping unit 20, so as to continue injecting the sizing material until the total amount of the injected sizing material reaches 9.8 cubic centimeters, at this time, the mold 21 still does not reach a complete mold closing state, the needle valve 181 closes the glue injection port 224, and the injection unit starts a metering action. Finally, as the movable mold 23 moves further toward the fixed mold 22, the molten rubber in the cavity is extruded until the cavity is filled, and a fully closed state is achieved, and the mold clamping force reaches a predetermined 150 tons. The fully clamped state is maintained for 10 seconds, and the molten rubber in the cavity is cooled and molded. Thereafter, the mold 21 is opened to a designated position, that is, the mold 21 reaches a fully opened state, and the air supply is turned on to blow air from the air blowing port 234 to release the product. So far, the injection molding and extrusion molding process of the orthodontic diaphragm is completed.

EXAMPLE III

The injection molding machine and the mold of the utility model are used for injection molding of the orthodontic diaphragm with the diameter D of 125mm and the thickness H of 0.75mm in the figures 8a and 8 b. Preferably, a computer-readable medium is provided in the injection molding machine, the computer-readable medium storing a program that, when executed, controls the injection extrusion method.

The design of the mold is the same as that of the first embodiment, and the description thereof is omitted.

The injection molding process of the orthodontic diaphragm is substantially the same as that of the second embodiment, except that when the control unit of the injection molding machine, which comprises the computer readable medium and runs the control program therein, receives the positioning signal, the movable mold 23 still continues to move, and simultaneously the needle valve 181 opens the glue injection port 224 and the injection unit 10 injects glue until the total amount of injected glue reaches 9.8 cubic centimeters, at which time, the mold 21 still does not reach the fully-closed state, the needle valve 181 closes the glue injection port 224, and the injection unit starts the metering action. That is, when the mold 21 is in a predetermined incompletely clamped state, the injection of the sizing material can be performed without stopping the movement of the mold 23.

Although various embodiments of the present invention have been described in detail herein, it is to be understood that the invention is not limited to the precise embodiments herein described and illustrated, and that other modifications and variations may be effected by one skilled in the art without departing from the spirit and scope of the invention. All such variations and modifications are intended to fall within the scope of the present invention. Moreover, all the components described herein may be replaced by other technically equivalent components.

Claims (8)

1. A die for producing an orthodontic diaphragm, the die comprising a stationary die and a movable die, the movable die being movable towards the stationary die to engage with the stationary die to define a die cavity for molding the orthodontic diaphragm,

wherein one of the fixed mold and the movable mold has a projecting wall disposed around the mold cavity, and the other of the fixed mold and the movable mold has a recess for receiving the projecting wall, the recess and the projecting wall cooperating with each other when the movable mold is engaged with the fixed mold to seal the mold cavity in a predetermined non-fully clamped state.

2. The mold according to claim 1, wherein the protruding wall is provided to the movable mold, and the recess is provided to the fixed mold.

3. The mold according to claim 2, wherein the stationary mold has an intermediate portion inside the recess for defining the cavity, the intermediate portion being flush with a stationary mold base surface of the stationary mold, and the movable mold has a central depression inside the protruding wall for defining the cavity, the central depression being depressed with respect to a movable mold base surface of the movable mold.

4. The mold according to any one of claims 1 to 3, characterized in that an inner side wall of the protruding wall extends parallel to a moving direction of the movable mold, and correspondingly, an inner side wall of the recess also extends parallel to the moving direction of the movable mold.

5. The mold according to any one of claims 1 to 3, characterized in that an outer side wall of the protruding wall is inclined with respect to a moving direction of the movable mold so that the protruding wall is tapered in the protruding direction of the protruding wall, and correspondingly, an outer side wall of the recess is inclined with respect to the moving direction of the movable mold so that the recess is tapered in a recessed direction of the recess.

6. The mold according to any one of claims 1 to 3, wherein the protruding wall is provided with a first discontinuity, the recess is provided with a second discontinuity, and the first discontinuity and the second discontinuity form a flash region when the movable mold is engaged with the fixed mold.

7. Mould according to any one of claims 1 to 3, characterized in that it comprises a hot runner system adapted to inject glue into the cavity, said hot runner system being provided with a needle valve adapted to close a glue injection opening of the mould for injecting glue, and hydraulic means adapted to control the movement of the needle valve and to keep it in position.

8. An injection molding machine for producing orthodontic film, characterized in that the injection molding machine comprises a mold according to any one of claims 1 to 7.

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