JP5709550B2 - Injection molding system - Google Patents

Description

  The present invention relates to an injection molding system that performs injection molding while heating and cooling a mold using water or steam.

In the injection filling process of the injection molding machine, the surface of the molten resin filled into the mold cavity from the injection apparatus is rapidly solidified from the moment when it comes into contact with the cavity surface of the mold. At this time, the transfer of the cavity surface of the mold to the molded product may be insufficient, or defects called weld lines and silver (silver) may occur on the surface of the molded product.
In order to prevent these problems and improve the quality of the molded product, in the series of processes such as injection filling, holding pressure, cooling, and mold opening / closing, the heating medium until the start of resin filling in the heat medium passage of the mold. A molding method has been proposed in which a mold is heated by supplying a cooling medium and a cooling medium is supplied after a predetermined time has elapsed from the start of resin filling until the mold is opened (for example, Patent Documents). 1). As a result, a mold heated in advance to a temperature equal to or higher than the thermal deformation temperature of the resin is filled with the molten resin to delay the solidification of the resin surface, and after the resin is filled, the mold is moved to the glass transition temperature of the resin or the thermal deformation temperature. The mold can be opened after cooling to the following, and the occurrence of defects as described above can be suppressed.

JP 2006-110905 A

  By the way, in the injection molding machine provided with the heating / cooling mechanism as described above, generally, the heating medium and the cooling medium that have passed through the mold are circulated from the mold to the heating medium supply device through a common return pipe. . In this common return pipe, since a high-temperature heating medium and a low-temperature cooling medium flow alternately, a temperature change occurs at the joint portion between the flange portion and the tubular portion of the pipe when the heat medium is switched. . In general, the joint between the flange portion and the tubular portion of the pipe is often integrated by welding or the like. There is a problem that the cooling medium leaks. If the heating medium or the cooling medium leaks, the stable molding operation is hindered, and the occurrence of rust or failure of the equipment, particularly when the high temperature medium leaks, greatly affects the safety to the surroundings.

This is because, for example, the tubular portion and the flange portion of the pipe have a thin thickness of 2.8 mm, but the flange portion is used as a connecting structural member for connecting the pipes with bolts or the like. Therefore, in order to be able to connect the pipes with sufficient rigidity, the flange portion is approximately 45 mm in thickness in the radial direction, that is, the portion excluding the pipe inner diameter from the flange diameter, and the thickness in the direction in which the pipes continue. That is, the thickness of the flange is 16 mm. For this reason, the dimensions differ greatly between the tubular portion and the flange portion, resulting in a large difference in heat capacity. That is, the temperature of the tubular part with a small wall thickness is likely to fluctuate depending on the temperature of the heating medium or cooling medium passing through the pipe, whereas the flange part with a large wall thickness and a large heat capacity is unlikely to rise in temperature. The temperature fluctuation rate is slow because the temperature is unlikely to drop. As a result, a temperature difference tends to occur between the tubular portion and the flange portion.
In the mold, heating with a heating medium and cooling with a cooling medium are repeated for each injection molding cycle in which a product is injection-molded. In order to produce a large number of products continuously, if the injection molding cycle is repeated many times, the degree of expansion and contraction due to heat differs between the tubular portion of the pipe and the flange portion. Thermal stress acts, and as a result, cracks and the like occur at the seam. In particular, when the tubular portion and the flange portion are integrated by welding or the like, the heat received by the tubular portion is taken away by the flange portion having a large heat capacity, and the temperature difference between the tubular portion and the flange portion becomes large, which is a temperature boundary. Cracks due to thermal stress are likely to occur in the welded portion (joint portion).
The present invention has been made on the basis of such a technical problem. Even when heating and cooling are repeated, the joint between the flange portion and the tubular portion of the pipe is prevented from cracking, and the reliability is improved. An object of the present invention is to provide an injection molding system that can perform such a process.

An injection molding system according to the present invention based on such an object includes: a mold clamping device that opens and closes a mold; an injection molding machine that includes an injection device that injects a molding material into a mold cavity; and a cavity that is heated. Therefore, a heating medium supply device that supplies a heating medium to a heating medium passage formed in the mold, a cooling medium supply device that supplies a cooling medium to the heating medium passage to cool the cavity, a heating medium supply device, and a cooling medium supply A heating / cooling control device for controlling supply of a heating medium and a cooling medium in the apparatus, a first common pipe for sending the heating medium or the cooling medium from the heating medium supply device or the cooling medium supply device to the heat medium passage, and heat And a second common pipe for returning to the heating medium supply device, the cooling medium supply device, or the drainage path through the medium passage. And at least one common piping of the 1st common piping and the 2nd common piping is comprised by connecting a plurality of piping members provided with a flange part at the end of a tubular body, and connecting a plurality of piping members In order to suppress the thermal stress generated between the flange portion and the tubular body, the portion is disposed so as to sandwich the flange portions of the pipe members facing each other, and has a pair having an inner diameter larger than the outer diameter of the tubular body of the pipe member It has the heat insulation structure part containing an annular plate and the fastening member which fastens a pair of annular plates in the outer peripheral side of a flange part.
In such a heat insulating structure portion, the annular plate is not fastened integrally with the flange portion, and is connected by sandwiching the flange portion between the pair of annular plates on the outer peripheral side of the flange portion. Therefore, when the flange portion is thermally expanded / contracted, if the flange portion expands / contracts in the radial direction, the deformation of the flange portion is not restrained by the annular plate, and the slippage between the flange portion and the annular plate occurs. Since it allows, thermal stress can be released.
Further, the contact surface (sandwich surface) between the flange portion and the annular plate is generally not a flat surface but has a minute unevenness due to roughness and waviness. That is, on the contact surface, the minute convex portions opposed to each other are only in point contact, and are not in full contact. Therefore, there is a layer of air that has a sufficiently low thermal conductivity and a large thermal insulation effect compared to metal in locations other than the convex portions that are in contact with each other in the sandwiching surface, so that the flange portion and the annular plate should be insulated. Can do. Thereby, the temperature difference of a flange part and a tubular body resulting from the heat | fever of a flange part being taken by the cyclic | annular plate can be suppressed.
Furthermore, since the annular plate has an inner diameter larger than the outer diameter of the tubular body, the annular plate does not contact the outer periphery of the body of the tubular body or only contacts locally, and there is no air between the tubular body. There will be a heat insulation layer. As a result, heat transfer between the piping members and the annular plates connecting them to each other is difficult to be performed, and the thermal effect due to this can be suppressed. The inner diameter of the annular plate is preferably larger than the outer diameter of the tubular body when the tubular body is thermally expanded. According to this, even when the tubular body is thermally expanded, the outer peripheral portion of the tubular portion does not come into contact with the inner peripheral portion of the annular plate, so that the thermal stress due to the heat of the tubular body being taken away by the annular plate can be prevented. It is valid.
Therefore, the connecting structural member for connecting the pipes with bolts or the like is an annular plate instead of the flange portion, and the flange portion provided at one end of the piping member is a flange to be sandwiched between the annular plates. Since a fastening structure in which an annular plate having a large heat capacity and a piping member having a small heat capacity are separated from each other is allowed, the flange portion and the fastening portion can have a heat insulating structure. The occurrence of cracks in the pipe joint due to thermal stress can be prevented.

Here, the heat insulation structure portion has a thickness t1 of the flange portion and a thickness t2 of the tubular body,
t2 ≦ t1 ≦ 2 × t2
It is preferable to satisfy. Thus, by reducing the difference in heat capacity between the flange portion and the tubular body, it is possible to suppress the difference in temperature change profile between the flange portion and the tubular body when a temperature change occurs due to the circulation of the heating medium or the cooling medium. .

  Furthermore, in such an injection molding system of the present invention, the temperature of the heating medium supplied to the common pipe is 110 to 250 ° C., and the temperature of the cooling medium supplied to the common pipe is 0 to 80 ° C. When the medium supplied to the pipe is switched from the heating medium to the cooling medium, the temperature change rate in the vicinity of the mold cavity surface is 0.5 to 10 ° C./sec, and the time required for one injection molding cycle is 30 to 120 sec. This is particularly effective when the temperature change in the common pipe is severe.

  Thus, in a piping member in which a high-temperature heating medium and a low-temperature cooling medium flow alternately, the fastening structure portion of the piping member is separated into at least a piping member and a fastening member, and the piping member is a tubular member provided with a flange portion at one end. The fastening member is a pair of annular plates having an inner diameter that is larger than the outer diameter of the body of the tubular member of the piping member and smaller than the outer diameter of the flange portion, and the tubular members facing each other by the annular plate By adopting a fastening structure in which the piping members are connected by sandwiching the outer peripheral sides of the flange portions, the piping members and the fastening members can be insulated and the temperature changes of the piping members can be made uniform.

According to the present invention, when the flange portion is thermally expanded / contracted, the flange portion expands / contracts in the radial direction. When the flange portion is deformed by expansion / contraction, the flange portion and the annular plate Slip occurs between them. Thereby, the deformation of the flange portion is not hindered, and stress can be prevented from concentrating on the welded portion between the flange portion and the tubular body at the time of deformation due to heat.
In addition, since there is a heat insulation layer by air between the annular plate and the flange portion or the tubular body, the heat of the piping member is taken away by the annular plate, and there is no part where the temperature is locally lowered, so the thermal stress is reduced. Can be suppressed.
In addition, by appropriately setting the thickness of the flange portion and the thickness of the tubular body, by reducing the difference in heat capacity between the flange portion and the tubular body, when the temperature change occurs due to the circulation of the heating medium and the cooling medium A temperature difference between the flange portion and the tubular body can be suppressed.
Therefore, even when the temperature change in the piping is severe, it is possible to prevent cracks from occurring in the joint portion between the flange portion and the tubular portion of the piping, and the reliability can be improved.

It is a figure which shows the whole structure of the injection molding machine in this Embodiment. It is a figure which shows the structure for performing temperature control of a metal mold | die. It is a figure which shows an example of a return piping part. It is sectional drawing which shows the structure of the connection part of piping. It is sectional drawing which shows the other example of a structure of the connection part of piping. It is sectional drawing which shows the structure of the connection part of piping in a comparative example.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a diagram for explaining a schematic configuration of an injection molding machine 10 constituting an injection system in the present embodiment.
As shown in FIG. 1, in the mold clamping device of the injection molding machine 10, a fixed die plate 12 is fixed to a base 11, and a fixed die (die) 13 is attached to the fixed die plate 12. A movable die (die) 14 facing the fixed die 13 is attached to a movable die plate 15 disposed facing the fixed die plate 12. The movable die plate 15 is guided by a guide rail 16 laid on the base 11, and is movable so as to face the fixed die plate 12 via a linear bearing. An electric ball screw 17 is used to move the movable die plate 15 for opening and closing the mold. It should be noted that there is no problem in using a hydraulic cylinder (not shown) for moving the movable die plate 15.

  A plurality of tie bars 18 are provided directly connected to a ram 19 that slides within a plurality of mold clamping hydraulic cylinders 12 a built in the fixed die plate 12. The tip of each tie bar 18 passes through the through hole of the movable die plate 15. A thread groove 18a is formed at the tip of the tie bar 18, and the half nut 18b disposed on the side opposite to the mold of the movable die plate 15 is engaged with the thread groove 18a, whereby the tie bar 18 is pulled in the direction of tension. Is fixed and restrained.

The injection unit (injection device) 20 is an electric drive method or a hydraulic drive method, and a frame 21 a integrated with the injection cylinder 21 is provided in an injection cylinder 21 having a nozzle that is in contact with the resin inlet of the fixed mold 13. Is provided. A pair of injection drive servomotors 22 and 22 are attached to the frame 21a symmetrically on both sides of the center line of the injection cylinder 21, and ball screw shafts 23 and 23 are directly connected to the output shafts of the injection drive servomotors 22 and 22, respectively. Yes. A pair of ball screw nuts 25, 25 attached to the moving frame 24 are screwed onto the ball screw shafts 23, 23. As the pair of injection drive servomotors 22 and 22 are synchronously driven, the injection screw 21b moves forward and backward in the injection cylinder 21 in the axial direction.
The injection screw 21b of the injection cylinder 21 is rotationally driven by an injection screw rotation drive motor 26 attached to the moving frame 24, and performs rotational feed and plasticization of the resin in the injection cylinder 21.

  The injection molding control device 50 sends hydraulic oil to the mold clamping hydraulic cylinder 12a in accordance with a molding process program, sends current to the injection drive servo motors 22 and 22 of the injection unit 20, and moves the injection screw 21b back and forth, thereby injecting the injection screw. An electric current is sent to the injection screw rotation drive motor 26 of 21b to instruct plasticization of the resin.

  The injection unit 20 injects molten resin into a mold cavity formed by clamping the fixed side mold 13 and the movable side mold 14. After the molded product is cooled and solidified, the movable mold 14 is released from the mold-clamping connection with the fixed mold 13 and is moved away from the fixed mold 13 by the operation of the moving electric ball screw 17 and the molded product is taken out. It is like that.

  Heat medium passages 30 and 31 for heating and cooling the mold surface are formed in the fixed mold 13 and the movable mold 14. The heat medium passages 30 and 31 are formed as close as possible to the mold cavity in order to transfer heat quickly and rapidly heat and cool the mold cavity surface. The heat medium passages 30 and 31 include a heat medium supply pipe 32I for sending the heat medium from the outside to the heat medium passages 30 and 31, and a heat medium passage 30 and 31 for discharging the heat medium to the outside. A heat medium discharge pipe 32O is connected to each other.

As shown in FIG. 2, a heating medium supply device 33 that supplies a heating medium such as steam and pressurized hot water and a cooling medium supply device 34 that supplies a cooling medium such as water and air to the heating medium supply pipe 32I. And are connected.
The heating medium supply device 33 feeds the heating medium to the heating medium passages 30 and 31 through the heating medium supply pipe 32I by a pump (not shown), and passes the heating medium through the heating medium passages 30 and 31 through the heating medium discharge pipe 32O. Circulate to the supply device 33. At this time, the heating medium is not circulated to the heating medium supply device and can be discharged to the outside through a drainage path (not shown).
The cooling medium supply device 34 sends the cooling medium to the heat medium passages 30 and 31 through the heat medium supply pipe 32I by a pump (not shown) and passes the cooling medium passing through the heat medium passages 30 and 31 through the heat medium discharge pipe 32O. It is circulated through the supply device 34.
The heat medium supply pipe 32I and the heat medium discharge pipe 32O are common pipes through which the heating medium and the cooling medium flow alternately or simultaneously.

  The heating medium supply device 33 and the cooling medium supply device 34 are connected to a temperature adjustment device 60. In the temperature adjusting device 60, in order to switch the heat medium supplied to the heat medium supply pipe 32I, the heating medium supply apparatus 33, the heating medium from the cooling medium supply apparatus 34, and the supply pipe for the cooling medium can be opened and closed. A valve (not shown) is provided.

  Each on-off valve of the temperature adjusting device 60 is controlled by a mold temperature control device (heating / cooling control device) 70 based on a predetermined program, and a heating medium supply pipe 32I for the heating medium and the cooling medium. Switching between supply and shut-off. That is, when heating the fixed side mold 13 and the movable side mold 14, the heating medium heated by the heating medium supply device 33 is sent to the heat medium supply pipe 32I, and the fixed side mold 13 and the movable side mold 14 are moved. When cooling, the cooling medium supplied from the cooling medium supply device 34 is fed into the heat medium supply pipe 32I.

As shown in FIGS. 1 and 2, a mold temperature sensor 40 is disposed in contact with the cavity surfaces of the fixed mold 13 and the movable mold 14. A mold temperature signal detected by the mold temperature sensor 40 is sent to a mold temperature control device (heating / cooling control device) 70.
2, the heat medium supply pipe 32I includes a heat medium temperature sensor 41 such as a thermocouple for detecting the temperature of the heat medium in the pipe, and a pressure sensor for detecting the pressure of the heat medium. Detection means for detecting the state of the heat medium in the pipe such as 42 may be provided. In this case, the heat medium temperature and pressure signals detected by the heat medium temperature sensor 41 and the pressure sensor 42 are sent to the mold temperature control device 70 in the same manner as the mold temperature signal detected by the mold temperature sensor 40. It is done.

  In the mold temperature control device 70, based on the mold temperature detected by the mold temperature sensor 40, and when the heat medium temperature sensor 41 and the pressure sensor 42 are used, the mold detected by the mold temperature sensor 40 is used. Based on the temperature and pressure of the heat medium detected by the heat medium temperature sensor 41 and the pressure sensor 42 in addition to the temperature, the temperature adjusting device 60 is controlled to open and close the heating medium supply device 33 and the cooling medium supply device 34. (Not shown) is opened and closed to control the supply timing of the heating medium and the cooling medium to the heat medium supply pipe 32I.

During a series of injection molding cycles, the mold temperature control device 70 executes processing determined based on a computer program introduced in advance and controls the supply of the heating medium and the cooling medium to the heat medium supply pipe 32I. Then, temperature control as shown below is performed.
In the process from mold closing to pressurization, the temperature control device 60 is controlled by the mold temperature control device 70, and the heating medium heated by the heating medium supply device 33 is sent to the heat medium supply pipe 32 </ b> I. The movable mold 14 is heated. Here, it is preferable to use a heating medium having a temperature of 110 to 250 ° C.
Then, after the fixed mold 13 and the movable mold 14 are heated, the injection of the molten resin into the mold cavity formed by clamping the fixed mold 13 and the movable mold 14 is started. . During or after injection, supply of the heating medium from the heating medium supply device 33 to the heat medium supply pipe 32I is stopped. The supply of the heating medium is stopped by controlling the temperature adjusting device 60 with the mold temperature control device 70.
When the injection of the resin is completed, the pressure in the mold cavity can be maintained. In addition, the temperature of the fixed mold 13 and the movable mold 14 may be supplied immediately after the supply of the heating medium is stopped, or the cooling medium may be supplied immediately after the injection to the holding pressure, or the cooling medium may not be supplied immediately. May be supplied or no medium may be supplied, and the mold cavity may be naturally radiated and kept warm or gradually cooled.

Next, the cooling process of the fixed mold 13 and the movable mold 14 will be described. The fixed mold 13 and the movable mold 14 are cooled by controlling the temperature adjusting device 60 with the mold temperature control device 70 so that the cooling medium supplied from the cooling medium supply device 34 is transferred to the heat medium supply pipe 32I. Send it in. Here, it is preferable to use a cooling medium having a temperature of 0 to 80 ° C.
The fixed side mold 13 and the movable side mold 14 are rapidly cooled by the feeding of the cooling medium. At this time, the temperature change rate in the vicinity of the mold surface when switching from the supply of the heating medium to the supply of the cooling medium is 0.5 to 10 ° C./sec. When the temperatures of the fixed mold 13 and the movable mold 14 are lowered, the mold temperature control device 70 controls the temperature adjusting device 60 to stop the supply of the cooling medium to the heat medium supply pipe 32I.
After the resin is cooled and solidified and a molded product is formed in the mold cavity, the movable mold 14 is released from the mold-clamping connection with the fixed mold 13 and opened. Subsequently, the movable mold 14 is further separated from the fixed mold 13 by the operation of the electric ball screw 17 for movement, and the molded product is taken out.
Thereafter, by repeating the same injection molding cycle as described above, the molded products can be sequentially injection-molded and produced. When repeating the same injection molding cycle as described above, the supply of the heating medium is resumed. At this time, the temperature change rate when switching from the cooling medium to the heating medium is 0.5 to 10 ° C./sec. It will be a thing. Here, it is preferable that one injection molding cycle is 30 to 120 sec.

Now, in the heat medium discharge pipe 32O for circulating the heating medium and the cooling medium that have passed through the heat medium passages 30 and 31 to the cooling medium supply device 34, a return pipe section (second Common piping) 100 is provided.
As shown in FIG. 3, the return pipe unit 100 includes a main pipe 101 that feeds the heat medium sent from the heat medium passages 30 and 31 to the heating medium supply device 33 and the cooling medium supply device 34 as it is, and the heat medium passage 30, When the heat medium sent out from 31 is steam, a condenser 102 that cools and condenses at least a part of the steam, and a branch pipe 103 that branches the heat medium from the main pipe 101 to the condenser 102. And.
The main pipe 101 is provided with an automatic opening / closing valve 104, and its opening / closing / opening is automatically adjusted and controlled by the control of the mold temperature control device 70.

The branch pipe 103 branches into two pipe lines 103A and 103B on the upstream side of the condenser 102. One conduit 103A is provided with a manual on-off valve 105, which is normally normally open.
The other pipe 103 </ b> B is provided with an automatic opening / closing valve 106, whose opening / closing / opening degree is automatically adjusted and controlled by the control of the mold temperature control device 70, and the pressure of the steam fed into the condenser 102. Can be adjusted.

In the return piping section 100 as described above, the automatic opening / closing valves 104 and 106 are incorporated in the intermediate portion of the tubular body 111 as a part of the piping member 110 having a predetermined length. The piping member 110 is integrally provided with an annular plate-shaped flange portion 112 that projects from the tubular body 111 toward the outer peripheral side at the end of the tubular body 111.
In such automatic opening / closing valves 104 and 106, the flange portions 112 at both ends are connected to the flange portions 122 provided at the end portions of the pipe members 120 constituting the pipe 103 </ b> B of the main pipe 101 and the branch pipe 103. .

Hereinafter, the structure of the heat insulation structure part of the connection part of such a piping member 110 and the piping member 120 is demonstrated.
As shown in FIG. 4, the flange portions 112 and 122 of the piping members 110 and 120 are connected using an annular plate 170.
The flange portions 112 and 122 of the piping members 110 and 120 are opposed to each other via an annular seal packing 171.
And the annular plates 170 and 170 are arrange | positioned at the both sides which pinched | interposed the flange parts 112 and 122. FIG. The annular plate 170 has an inner diameter smaller than the outer diameter of the flange portions 112 and 122 and larger than the outer diameter of the tubular bodies 111 and 121 of the piping members 110 and 120, so as not to contact the tubular bodies 111 and 121. Is provided. The annular plates 170 and 170 are fastened by bolts and nuts (fastening members) 172 and 172 on the outer peripheral portion thereof. The annular plate 170 may have any shape as long as the flange portion such as a split ring shape can be sandwiched in addition to the illustrated integral ring shape. In FIG. 4, the flange portions 112 and 122 are directly sandwiched between the annular plates 170, but a heat insulating material may be inserted between the flange portions 112 and 122 and the annular plate 170. The heat insulating material may be a fiber heat insulating material, a foam heat insulating material, a resin heat insulating material, or a vacuum heat insulating material. Or you may use combining various heat insulating materials.

Here, when the thickness of the flange portions 112 and 122 is t1, and the thickness of the tubular bodies 111 and 121 is t2,
t2 ≦ t1 ≦ 2 × t2
It is preferable to set so that.

  Moreover, it is preferable to form the piping members 110 and 120 with steel materials, such as SUS304. The annular plates 170 and 170 can be formed of the same material as the piping members 110 and 120, or can be formed of a material having lower thermal conductivity than the piping members 110 and 120, such as SUS420J2.

  In addition, the surface of the annular plate 170 is roughened or uneven, thereby reducing the contact area between the annular plates 170 and 170 and the flange portions 112 and 122 of the piping members 110 and 120. Thereby, the heat insulation effect between the annular plates 170 and 170 and the flange parts 112 and 122 of the piping members 110 and 120 can be enlarged.

In such a configuration, the annular plates 170 and 170 that connect the flange portions 112 and 122 of the piping members 110 and 120 are annular, so that the tubular bodies 111 and 121 do not come into contact with each other. The heat insulating layer A is formed between the layer 121 and the air. As a result, heat transfer between the piping members 110 and 120 and the annular plates 170 and 170 that connect them to each other is difficult to be performed, and the thermal influence of the annular plates 170 and 170 can be suppressed.
Furthermore, when the contact area between the annular plates 170 and 170 and the flange portions 112 and 122 of the piping members 110 and 120 is reduced by increasing the surface roughness of the annular plate 170 or by forming irregularities, the annular plate 170 is reduced. , 170 and the flange portions 112 and 122 of the piping members 110 and 120 are difficult to conduct heat. Thereby, the thermal influence by the annular plates 170 and 170 can be suppressed.
Further, when the flange portions 112 and 122 are thermally expanded and contracted, they are expanded and contracted in the radial direction. However, when the flange portions 112 and 122 are deformed due to expansion and contraction, the flange portions 112 and 122 Slip occurs between the annular plate 170. Thereby, the deformation of the flange portions 112 and 122 is not hindered, and the thermal stress between the flange portions 112 and 122 and the flange portions 112 and 122 and the tubular bodies 111 and 121 can be suppressed during the deformation due to heat.

  In addition, by appropriately setting the thicknesses t1 and t2 of the flange portions 112 and 122 and the tubular bodies 111 and 121 within the above-described range, a difference in heat capacity between the flange portions 112 and 122 and the tubular bodies 111 and 121 is set. The temperature difference can be suppressed by reducing the temperature. Also by this, the thermal stress between the flange portions 112 and 122 and the flange portions 112 and 122 and the tubular bodies 111 and 121 can be suppressed at the time of deformation due to heat.

  Therefore, it is possible to suppress the occurrence of a temperature difference between the tubular bodies 111 and 121 and the flange portions 112 and 122 of the piping members 110 and 120 that are integrated. The flange portions 112 and 122 may be provided in any form such as drawing or cutting with respect to the piping members 110 and 120. In particular, when the thickness t1 of the flange portions 112 and 122 and the thickness t2 of the tubular body satisfy t2 ≦ t1 ≦ 2 × t2, the flange portions 112 and 122 may be provided on the piping members 110 and 120 by welding. . As a result, it is possible to prevent a thermal stress from acting on the joint between the tubular bodies 111 and 121 and the flange portions 112 and 122 of the piping member due to a thermal effect, thereby causing a crack or the like at the joint. Thereby, the reliability of the connection part of the piping member 110 and the piping member 120 can be improved.

The flange portions 112 and 122 of the piping members 110 and 120 may be provided in any form with respect to the tubular bodies 111 and 121. For example, as shown in FIG. 5, piping members 110 and 120 are obtained by welding a member in which the flange portions 112 and 122 and the tubular bodies 111 and 121 are integrated to another tubular body 115 and 125 at a welded portion W. May be formed.
In such a case, by providing the welded portion W at a position that is sufficiently away from the flange portions 112 and 122 that tend to increase the heat capacity and is not affected by the thermal effects of the flange portions 112 and 122, for example, the tubular bodies 111 and 121 are formed. Even if it is a welded structure, the welded portion W can be prevented from cracking due to thermal stress.

By the way, in the injection molding machine 10 which employ | adopts a structure as shown in said each embodiment, the following structures can also be employ | adopted.
That is, as shown in FIG. 3, the pipe 103B provided with the automatic opening / closing valve 106 is connected to the pipe 103A by a T-shaped elbow 180 so as to be orthogonal to the pipe 103A. The pipe 103 </ b> A is formed with a loop portion 181 that loops once in a spiral manner on both sides of the T-shaped elbow 180. When the pipe line 103B provided with the automatic opening / closing valve 106 expands and contracts in the axial direction, the loop portion 181 expands and contracts by closing and opening so that the diameter of the pipe line 181 expands and contracts. Thereby, it becomes possible to permit the deformation | transformation by the thermal expansion of the pipe line 103B.
Although not shown, the loop-shaped pipe similar to the loop part 181 can be applied to a bent part or a long pipe part. Since long pipes have a large amount of thermal expansion or contraction due to temperature changes, when using simple straight pipes, the pipe joints will be spread or pulled to generate thermal stress. Become. In this case, if a loop-shaped pipe is used, when a long pipe expands and contracts in the axial direction, the loop-shaped pipe can be expanded and contracted by expanding and contracting to relieve thermal stress by expanding and contracting. . In the bent portion, thermal stress may be generated when the bending angle is expanded or reduced due to thermal expansion or contraction caused by a temperature change of the pipe. Even in this case, if the loop-shaped pipe is used, the loop-shaped pipe can be closed or opened so that the diameter of the loop-shaped pipe is enlarged or reduced, and the thermal stress of the bent portion can be relieved.
Also by this, the stress given to the connection part vicinity of the tubular bodies 111 and 121 and the flange parts 112 and 122 can be suppressed.

Moreover, even if it has the structure shown in each embodiment as described above, there is a possibility that a crack will occur in the piping part 100 and the liquid will leak.
In such a case, the liquid leakage sensor 190 is provided, and when the liquid leakage sensor 190 detects the liquid leakage, the supply of the heat medium to the heat medium passages 30 and 31 of the injection unit 20 is shut off. It may be controlled by the injection unit 20.

  Here, as the liquid leakage sensor 190, a humidity sensor 191 can be provided in the vicinity of a place where damage is likely to occur due to thermal stress. Further, a drain pan 192 may be provided below the apparatus of the injection unit 20, and a water leak sensor may be provided in the drain pan 192.

In the above embodiment, the present invention is applied to a connecting portion of the piping members 110 and 120 constituting the second common pipe for returning the heat medium discharged from the mold to the heating medium supply device, the cooling medium supply device, or the drainage path. However, the present invention is applied to a connecting portion (not shown) on a common pipe (first common pipe) for supplying a heat medium from a heating medium supply device or a cooling medium supply device to a mold. May be. Moreover, about the structure of injection molding machines other than a connection part, it can also be set as the structure other than having mentioned above.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

Now, since the effect of the configuration in the present embodiment as described above has been verified, the result will be shown.
(Example)
The connecting portion of the piping member to be verified has the configuration shown in FIG. 4, the thickness t1 of the flange portions 112 and 122 is 2.8 mm, the thickness t2 of the tubular bodies 111 and 121 is 2.8 mm, and the pipe diameter Was 25 mm.
(Comparative Example 1)
On the other hand, the thing of a structure as shown to Fig.6 (a) was prepared as a comparison object. That is, the flange parts 201 and 201 which are the structure of the connection part of the conventional piping member were directly connected by the bolt and nut 202. Here, the thickness t1 ′ of the flange portion 201 was 14 mm, the thickness t2 ′ of the tubular body 203 was 2.8 mm, and the tube diameter was 25 mm.
Here, in both the examples and comparative examples, the material of the piping member was SUS304.
(Comparative Example 2)
Furthermore, the thing of a structure as shown in FIG.6 (b) was prepared as a comparison object. In addition to the structure shown in FIG. 6 (a), a cylindrical sleeve 205 made of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), which is a resin-based heat insulating material, is provided at the connecting portion of the piping member. Provided. The thickness of the sleeve 205 was 2 mm, and the length L was 30 mm.

  In Examples and Comparative Examples 1 and 2 as described above, heating by circulating steam at 190 ° C. is performed for 60 seconds, cooling by circulating water at 30 ° C. is performed for 60 seconds, and a cycle of 120 seconds is repeated as a whole. The amplitude of the stress generated in the piping member at the X part in FIG. 6 was measured with a strain gauge.

As a result, the stress amplitude is 438 MPa in the comparative example 1 in which the flange portions 201 and 201 are directly connected by the bolt and nut 202, and the stress amplitude is compared in the comparative example 2 in which the sleeve 205 made of a heat insulating material is provided. Was 262 MPa.
On the other hand, in Example 1 corresponding to the configuration in the present embodiment, the stress amplitude is 182 MPa, and the stress in the connecting portion of the piping member is greatly reduced by the configuration in the present embodiment even without providing a heat insulating material. It was confirmed that it was possible.

  DESCRIPTION OF SYMBOLS 10 ... Injection molding machine, 20 ... Injection unit (injection apparatus), 21 ... Injection cylinder, 30 ... Heat medium passage, 32I ... Heat medium supply pipe, 32O ... Heat medium discharge pipe, 33 ... Heating medium supply apparatus, 34 ... Cooling Medium supply device, 50 ... Injection molding control device, 60 ... Temperature adjustment device, 70 ... Mold temperature control device (heating / cooling control device), 100 ... Piping section (second common piping), 110, 120 ... Piping members 111, 121 ... tubular body, 112, 122 ... flange part, 170 ... annular plate, 171 ... seal packing, 172 ... bolt and nut (fastening member), A ... heat insulation layer, W ... welded part

Claims (3)

A mold clamping device for opening and closing the mold, and an injection molding machine including an injection device for injecting a molding material into the cavity of the mold;
A heating medium supply device for supplying a heating medium to a heat medium passage formed in the mold for heating the cavity;
A cooling medium supply device for supplying a cooling medium to the heat medium passage to cool the cavity;
The heating medium supply device, the heating medium in the cooling medium supply device, a heating / cooling control device for controlling the supply of the cooling medium, and
A first common pipe for feeding the heating medium or the cooling medium from the heating medium supply apparatus or the cooling medium supply apparatus into the heat medium passage, and the heating medium supply apparatus or the cooling medium via the heat medium passage A second common pipe for returning to the supply device or the drainage path,
At least one common pipe of the first common pipe and the second common pipe is configured by connecting a plurality of pipe members each having a flange portion at an end of a tubular body,
In order to suppress the thermal stress generated between the flange portion and the tubular body, the connecting portion of the plurality of piping members,
A pair of annular plates disposed so as to sandwich the flange portions of the pipe members facing each other, and having an inner diameter larger than the outer diameter of the tubular body of the pipe members;
An injection molding system comprising: a heat insulating structure portion including a fastening member that fastens a pair of the annular plates on the outer peripheral side of the flange portion. The heat insulating structure portion has a thickness t1 of the flange portion and a thickness t2 of the tubular body,
t2 ≦ t1 ≦ 2 × t2
The injection molding system according to claim 1, wherein: The temperature of the heating medium supplied to the common pipe is 110 to 250 ° C.,
The temperature of the cooling medium supplied to the common pipe is 0 to 80 ° C.,
The temperature change rate in the vicinity of the mold cavity surface when switching the medium supplied to the common pipe from the heating medium to the cooling medium is 0.5 to 10 ° C./sec,
The injection molding system according to claim 1 or 2, wherein the time required for one injection molding cycle is 30 to 120 seconds.

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