JP5811682B2 - Mold cooling apparatus and mold cooling method - Google Patents

Description

  The present invention relates to a mold cooling apparatus and a mold cooling method.

  Molded articles are molded by introducing a molten substance (molten metal or molten resin) into the mold cavity and then cooling and solidifying the molten substance in the cavity. In order to shorten the molding cycle by increasing the cooling and solidifying rate of the molten substance in the cavity, a cooling device or a cooling method capable of efficiently cooling the mold has been proposed.

  Patent Document 1 discloses a structure of a cooling water pipe inserted into a bottomed cooling hole for circulating cooling water formed in a mold. The tip of the cooling water pipe (inner pipe) is opened so that cooling water can be discharged, and the cooling water pipe is inserted into the cooling hole from the opened tip side. In addition, a guide member formed in a spiral shape is provided on the outer periphery of the cooling water pipe. The cooling water discharged from the tip of the cooling water pipe inserted into the cooling hole flows between the outer peripheral wall of the cooling water pipe and the side wall of the cooling hole and flows in the cooling hole from the bottom side to the opening side, and from the opening side. It is discharged outside. The cooling water flowing between the outer peripheral wall of the cooling water pipe and the side wall of the cooling hole flows spirally along a helical guide member provided on the outer periphery of the cooling water pipe. As the cooling water flows spirally, the residence time in the cooling holes of the cooling water increases. As the residence time increases, the amount of heat that the cooling water takes from the mold increases. For this reason, the internal cooling efficiency of a metal mold | die improves.

  By the way, when a high-temperature molten material is introduced into a mold cooled with cooling water, thermal stress acts on the mold. When the wall surface of the cooling hole formed in the mold is corroded during the action of thermal stress, there is a concern about stress corrosion cracking of the mold. Therefore, a method of cooling the mold while preventing the corrosion of the wall surface of the cooling hole has been proposed.

  For example, Patent Document 2 discloses a cooling method in which a mold is internally cooled by adding a rust preventive agent and circulating cooling water adjusted to be alkaline with a pH of 9 or more through a cooling hole of the mold. According to this method, since the alkaline cooling water containing the rust preventive agent flows in the cooling hole, a passive film is formed on the wall surface of the cooling hole. Corrosion of the wall of the cooling hole is prevented by the passive film (anodic corrosion prevention method).

  Patent Document 3 discloses a mold storage method that rusts the cooling water channel of the mold by means of electric corrosion protection during mold storage. According to this method, the cooling water channel formed in the mold when the mold is stored is connected to the water supply device. By supplying water from the water tank of the water supply device to the cooling water channel of the mold, the cooling water channel is filled with water. When the cooling water channel is filled with water, an anode electrode is introduced into the water tank of the water supply device, and a potential difference is generated between the mold and the anode electrode. Thereby, the anticorrosion current flows from the anode electrode to the mold, and the occurrence of corrosion is prevented (cathodic anticorrosion method by an external power supply method). By preventing the occurrence of corrosion, the occurrence of rust is also prevented.

JP 2007-144457 A JP 2007-216252 A JP 2004-353209 A

(Problems to be solved by the invention)
According to the cooling method described in Patent Document 1, since the wall surface of the cooling hole of the mold is not anticorrosive, there is a concern about stress corrosion cracking due to corrosion of the wall surface of the cooling hole. Also, in order to give the mold a strength that does not cause stress corrosion cracking, the distance between the bottom of the cooling hole and the cavity surface (mold surface) must be set long (for example, about 15 mm or more). Don't be. However, the longer the distance is, the smaller the amount of heat transferred from the cavity to the cooling hole, and the less the amount of heat lost to the cooling water flowing through the cooling hole. Therefore, the internal cooling efficiency of a metal mold | die falls.

  According to the anode anticorrosion method described in Patent Document 2, a rust inhibitor is mixed in the cooling water, and the pH of the cooling water is adjusted to be alkaline, so that corrosion of the wall surface of the cooling hole is prevented. Therefore, the possibility of stress corrosion cracking is low, and therefore the distance between the bottom of the cooling hole and the cavity surface can be shortened, and the internal cooling efficiency can be increased. However, when such an anticorrosion method is actually performed, a dedicated circulation circuit for circulating the alkaline cooling water must be formed. In addition, a dedicated heat exchange device and pump must be installed in the dedicated circulation circuit. Therefore, the capital investment cost increases, and the productivity per space is reduced due to the increase in installation space. Furthermore, the running cost is high because it is necessary to compensate for the lack of rust preventive agent due to evaporation or drainage of the cooling water. In addition, since the anticorrosion effect changes depending on the quality of the cooling water (dissolved oxygen concentration, etc.), periodic water quality checks are necessary and time-consuming.

  According to the cathodic protection method based on the external power source system described in Patent Document 3, the anode electrode is provided in the water tank of the water supply device externally connected to the cooling water channel of the mold. Therefore, the anticorrosion current from the anode electrode flows only in the portion near the anode electrode in the wall surface of the cooling water channel of the mold, that is, the portion near the portion connected to the water tank of the water supply device. For this reason, the anticorrosion current cannot flow uniformly over the entire wall surface of the cooling water channel, and as a result, there is a high possibility that corrosion will occur in a portion far from the anode electrode. In addition, since stress corrosion cracking of the mold often occurs during the operation of the mold, even if the anticorrosion is performed during the storage of the mold as in Patent Document 3, corrosion occurs during the operation of the mold. In some cases, stress corrosion cracking cannot be prevented.

  Thus, in the prior art, a cooling device and a cooling method that sufficiently prevent stress corrosion cracking during operation of the mold and that are configured at low cost and have high cooling efficiency have not been proposed. An object of the present invention is to provide a mold cooling device and a cooling method that can sufficiently prevent corrosion even during the operation of the mold, and that can increase the cooling efficiency at low cost. And

(Means for solving the problem)
The present invention is a cooling system that is formed in a cylindrical shape, has an opening at the tip, is inserted from the tip into a bottomed cooling hole formed in a mold, and discharges cooling water from the tip into the bottomed cooling hole. A mold cooling device comprising a water pipe and a protrusion provided to protrude from an outer peripheral wall of the cooling water pipe, wherein cooling water is discharged into the bottomed cooling hole from the tip of the cooling water pipe. The mold cooling device is configured so that a corrosion-proof current flows from the protruding portion to the wall surface of the bottomed cooling hole when the projection is on.

  Further, the present invention inserts a cooling water pipe formed in a cylindrical shape, having a tip opened and a protruding portion protruding from an outer peripheral wall thereof into a bottomed cooling hole formed in a mold from the tip. In this state, a cooling water discharge step for discharging cooling water from the tip into the bottomed cooling hole, and cooling water from the tip of the cooling water pipe into the bottomed cooling hole in the cooling water discharge step. There is provided a method for cooling a mold, comprising: an anticorrosion step for electrically preventing the mold by causing an anticorrosion current to flow from the protrusion to the wall surface of the bottomed cooling hole when discharged.

  According to the present invention, when cooling water is discharged from the tip of the cooling water pipe in a state where the cooling water pipe is inserted into the bottomed cooling hole of the mold, the cooling water is separated from the outer peripheral wall of the cooling water pipe and the bottomed cooling hole. It flows from the bottom side of the bottomed cooling hole to the opening side through the space between the side walls. At this time, the linear flow of the cooling water from the bottom side of the bottomed cooling hole toward the opening side is inhibited by the protruding portion provided on the cooling water pipe so as to protrude from the outer peripheral wall of the cooling water pipe. For this reason, the residence time of cooling water increases. In other words, the protrusion is opened from the bottom side of the bottomed cooling hole through which the cooling water discharged from the tip of the cooling water pipe into the bottomed cooling hole passes between the outer peripheral wall of the cooling water pipe and the side wall of the bottomed cooling hole. It has the function of increasing the residence time until it is discharged to the side. By increasing the residence time of the cooling water, the amount of heat that the cooling water takes from the mold increases. For this reason, the mold can be efficiently cooled inside.

  In addition, when cooling water is discharged from the cooling water pipe into the bottomed cooling hole and the mold is internally cooled, the bottom has a bottom from the protrusion provided on the outer peripheral wall of the cooling water pipe inserted into the bottomed cooling hole. The anticorrosion current flows through the cooling water flowing in the bottomed cooling hole on the wall surface of the cooling hole. By this anticorrosive current, the entire wall surface of the bottomed cooling hole is substantially uniformly anticorrosive. Therefore, corrosion of the wall surface of the bottomed cooling hole can be suppressed, and as a result, stress corrosion cracking can be effectively prevented.

  Furthermore, as a result of effective prevention of stress corrosion cracking by means of cathodic protection, the distance between the bottom of the bottomed cooling hole and the cavity surface can be reduced to, for example, about 5 mm. This increases the amount of heat taken by the cooling water flowing through the bottomed cooling hole from the mold. Therefore, the internal cooling efficiency of the mold is further improved.

  As described above, according to the present invention, the protrusion provided on the cooling water pipe inserted into the bottomed cooling hole of the mold is used as an anode for cathodic protection, thereby preventing the corrosion during the operation of the mold. It is possible. Further, since the anticorrosion current flows from the protruding portion to the wall surface of the bottomed cooling hole, the wall surface of the bottomed cooling hole can be uniformly anticorrosive. And since it is possible to prevent stress corrosion cracking during the operation of the mold by means of cathodic protection, it is possible to increase the internal cooling efficiency by narrowing the distance between the bottom of the bottomed cooling hole and the cavity surface. As a result of increasing the internal cooling efficiency, the molding cycle can be shortened. Also, by applying a release agent directly to the cavity surface of the mold, external cooling for cooling the mold can be eliminated or the external cooling time can be shortened. Here, when the mold is externally cooled, the mold life is reduced by the thermal shock acting on the cavity surface. Therefore, the life of the mold can be extended by improving the internal cooling efficiency of the mold and eliminating the external cooling or shortening the external cooling time as in the present invention. In addition, since it is possible to prevent corrosion without mixing a rust inhibitor into the cooling water or adjusting the cooling water to be alkaline, there is no need to install a dedicated cooling water circulation circuit, etc., and other cooling water circulation circuits Can be used. Therefore, an inexpensive and compact cooling device can be provided.

  The protrusion allows the cooling water in the bottomed cooling hole to flow from the bottom side of the bottomed cooling hole to the opening side through the gap between the outer peripheral wall of the cooling water pipe and the side wall of the bottomed cooling hole, And it is good to form so that it may protrude from the outer peripheral wall of a cooling water pipe | tube so that cooling water may inhibit flowing linearly through the said clearance gap. In particular, the protruding portion is such that the space between the outer peripheral wall of the cooling water pipe and the side wall of the bottomed cooling hole in the cross section perpendicular to the axis of formation of the bottomed cooling hole is not blocked by the protruding portion, And it is good to provide in the outer peripheral wall of a cooling water pipe | tube so that it may inhibit that a cooling water flows linearly from the bottom part side of a bottomed cooling hole to an opening part side.

  The protrusion may be formed of a material that can be an electrode. In this case, the mold cooling device of the present invention includes a cathode electrically connected to the mold and an anode electrically connected to the protrusion, and is cooled from the tip of the cooling water pipe. A power supply device may be provided that applies a voltage between the mold and the protrusion when water is discharged into the bottomed cooling hole.

  According to this configuration, a voltage is applied between the mold and the projecting part so that the mold side becomes a cathode and the projecting part becomes an anode by operating the power supply device in the cathodic protection process. As a result, an anticorrosion current flows from the protruding portion to the mold, and the mold is electrically protected (cathodic protection). By such anticorrosion by the external power supply system, the wall surface of the bottomed cooling hole of the mold is effectively prevented from corrosion during the mold operation.

  The power supply device is operated when the mold is in operation, that is, when cooling water is discharged from the cooling water pipe into the bottomed cooling hole and the mold is cooled by the discharged cooling water, that is, the bottomed cooling hole is in the cooling water. Activated when it is filled with. In addition, the cooling device of the present invention includes a control device that controls the voltage applied between the mold and the protruding portion so that the mold is effectively electrically protected during operation of the power supply device. Also good.

  Moreover, in order to prevent a short circuit of the power supply device, it is preferable that the protruding portion is inserted into the bottomed cooling hole so as not to contact the wall surface of the bottomed cooling hole. Further, it is more preferable that the protruding portion is made of a material that can serve as an anode for cathodic protection by an external power supply system. For example, it may be formed of platinum, gold, copper, carbon or the like.

  Further, the protrusion may be formed of a material having a higher ionization tendency than the mold, and the mold and the protrusion may be electrically connected. According to this configuration, since the ionization tendency of the protrusions is higher than the ionization tendency of the mold, the anticorrosion current flows from the protrusions to the mold in the cathodic protection process, and the mold is electrically protected. Such anticorrosion by the galvanic anode method also effectively prevents the wall surface of the bottomed cooling hole of the mold during the operation of the mold.

  In this case (in the case of cathodic protection by a galvanic anode method), the protruding portion may be electrically connected to the mold outside the mold, and the mold may be connected to the mold within the mold. It may be electrically connected. In order to electrically connect the protruding portion to the mold outside the mold, it is preferable to connect both of them with electric wiring. Further, in order to electrically connect the protruding portion to the mold inside the mold, the protruding portion is provided with the bottomed cooling hole so that the protruding portion has a portion that contacts the wall surface of the bottomed cooling hole of the mold. Should be placed inside. By carrying out like this, an anticorrosion electric current flows into the wall surface of a bottomed cooling hole from the part which is not contacting the wall surface of a bottomed cooling hole among protrusion parts in an electrocorrosion prevention process.

  It is preferable that the outer peripheral wall of the cooling water pipe is formed of an electrically insulating material, and the protruding portion is spirally wound around the outer peripheral wall of the cooling water pipe. According to this, since the protrusion is spirally wound around the outer peripheral wall of the cooling water pipe, the cooling water discharged from the cooling water pipe is cooled along the outer peripheral wall of the cooling water pipe and the bottomed cooling along the spiral shape of the protrusion. It flows spirally between the side walls of the holes. Due to the formation of such a spiral flow, the residence time of the cooling water in the bottomed cooling hole is increased. Moreover, since the outer peripheral wall of the cooling water pipe is formed of an electrically insulating material, it is possible to prevent the current from flowing from the protruding portion to the cooling water pipe during the electric protection.

  The protrusion may be formed of a wire-like member (for example, a platinum-plated titanium wire or a zinc wire). In this case, the protrusion may be formed by winding a wire-like member around the outer peripheral wall of the cooling water pipe in a spiral manner. Further, the cooling water pipe may be inserted into the bottomed cooling hole so that the axial direction thereof substantially coincides with the formation direction of the bottomed cooling hole.

  The outer peripheral wall of the cooling water pipe may be formed of an electrically insulating resin material. In this case, the outer peripheral wall of the cooling water pipe is preferably formed of an insulating resin material having a slight heat resistance. Since the temperature of the cooling water is around 50 ° C., it is preferable that the outer peripheral wall of the cooling water pipe is formed of an insulating resin material that does not soften even when heated to about 50 ° C. Further, the cooling water pipe itself may be formed of an insulating resin material, or the cooling water pipe may be formed by covering the outer periphery of a pipe whose base material is a metal material with an insulating resin material.

It is the schematic which shows the cooling device which concerns on 1st Embodiment of this invention, and the metal mold | die to which the cooling device is applied. It is a schematic sectional drawing which shows the concrete structure and power supply device of the cooling water pipe unit which concern on 1st Embodiment inserted in the cooling hole of a metal mold | die, and a cooling hole. It is the schematic which shows the metal mold | die to which the cooling device which concerns on 2nd Embodiment of this invention, and the cooling device is applied. It is a schematic sectional drawing which shows the concrete structure of the cooling hole of a metal mold | die, and the cooling water pipe unit which concerns on 2nd Embodiment inserted in the cooling hole. It is a schematic sectional drawing which shows the concrete structure of the cooling water pipe unit which concerns on the cooling hole of a metal mold | die, and the modification of 2nd Embodiment inserted in the cooling hole.

(First embodiment)
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a schematic view showing a mold cooling apparatus according to the first embodiment and a mold to which the cooling apparatus is applied. In FIG. 1, a mold 10 is, for example, a mold for aluminum die casting, and is made of hot die steel (for example, SKD61). The mold 10 has a fixed mold 11 and a movable mold 12. A cavity 13 is formed in a space portion surrounded by the mold matching surface of the fixed mold 11 and the mold matching surface of the movable mold 12. A high-temperature molten substance (for example, molten aluminum) is introduced into the cavity 13. The molten material in the cavity 13 is cooled and solidified as the mold 10 is deprived of heat. The cooled and solidified mold product is taken out from the mold 10.

  The mold 10 is formed with a plurality of bottomed cooling holes 14 through which cooling water flows. In the drawing, four cooling holes 14 are formed in the fixed mold 11 and four cooling holes 14 in the movable mold 12, but this is not restrictive. The cooling holes 14 are formed at locations where the mold 10 is efficiently cooled internally by the flow of cooling water there. A cooling water pipe unit 23 of the cooling device 20 is inserted into each cooling hole 14.

  The cooling device 20 has a function of cooling the mold 10 and electrically preventing the cooling holes 14 formed in the mold 10 during the mold operation. The cooling device 20 includes a water supply pipe 21, a drainage pipe 22, a plurality of cooling water pipe units 23, and a power supply device 25 (see FIG. 2). A water supply connecting coupler 21 a is attached to one end of the water supply pipe 21. The water supply connection coupler 21a is connected to a water supply line A installed in a factory for manufacturing a molded product. A drainage connection coupler 22 a is attached to one end of the drainage pipe 22. The drainage connection coupler 22a is connected to a drainage line B installed in a factory or the like. Note that a cooling tower C is generally installed in a factory, and the cooling water heated from the drainage line B is supplied to the cooling tower C. The cooling tower C cools the heated cooling water and supplies the cooled cooling water to the water supply line A.

  The water supply pipe 21 branches into two pipes at a portion located downstream from the one end when the one end to which the water supply connection coupler 21a is attached is defined as the upstream side. Each branched pipe (primary branch water supply pipe) is further branched into a plurality of pipes (four in FIG. 1) on the downstream side. A cooling water pipe unit 23 is connected to each downstream end of a plurality of re-branched pipes (secondary branch water supply pipes).

  The drainage pipe 22 branches into two pipes at a portion located upstream from the one end when the one end to which the drainage connection coupler 22a is attached is defined as the downstream side. Each branched pipe (primary branch drain pipe) is further branched into a plurality of pipes (four in FIG. 1) on the upstream side. A cooling water pipe unit 23 is connected to each upstream end of a plurality of re-branched pipes (secondary branch drain pipes).

  FIG. 2 is a schematic sectional view showing the cooling hole 14 of the fixed mold 11 and the specific structure of the cooling water pipe unit 23 according to the first embodiment inserted into the cooling hole 14 and the power supply device 25. As shown in FIG. 2, the cooling hole 14 has a screw hole 141 that opens on the mold surface different from the cavity surface CS, and extends from the bottom of the screw hole 141 in the direction toward the cavity surface CS. 141 and a cooling hole 142 formed coaxially. The diameter of the screw hole 141 is larger than the diameter of the cooling hole 142.

  The cooling water pipe unit 23 includes a cooling water pipe 231, a cooling plug 232, and a coil member 233 corresponding to the protruding portion of the present invention. The cooling water pipe 231 is formed in a cylindrical shape, and its tip 231a is opened. In this embodiment, the cooling water pipe 231 is formed of an electrically insulating resin (for example, vinyl chloride resin or ABS resin). Note that the cooling water pipe 231 may be formed by forming the main body of the cooling water pipe from a pipe-shaped metal material and coating the outer peripheral wall with an electrically insulating resin.

  The cooling plug 232 is also formed in a cylindrical shape. The inner diameter of the cooling plug 232 is larger than the outer diameter of the cooling water pipe 231. A male screw is formed on the outer peripheral wall of the cooling plug 232. On the other hand, a female screw is formed on the inner peripheral wall of the screw hole portion 141 so that the cooling plug 232 can be screwed into the screw hole portion 141.

  In addition, the cooling water pipe 231 is fixed to the cooling plug 232 so that the cooling water pipe 231 is coaxially disposed inside the cooling plug 232 and has a portion protruding from the tip of the cooling plug 232. In the present embodiment, a rib 234 is partially provided between the outer peripheral wall portion of the cooling water pipe 231 and the inner peripheral wall portion of the cooling plug 232, and the cooling water pipe 231 is fixed to the cooling plug 232 by the rib 234.

  The coil member 233 is formed of a material that can be an anode used for cathodic protection by an external power supply method. In this embodiment, the coil member 233 is formed of a wire (platinum-plated titanium wire) obtained by applying platinum plating to a titanium wire as a core material. As shown in FIG. 2, a coil member 233 protruding from the outer peripheral wall of the cooling water pipe 231 is formed by spirally winding this platinum-plated titanium wire around the outer peripheral wall of the cooling water pipe 231 protruding from the cooling plug 232. The The coil member 233 is preferably fixed to the cooling water pipe 231 so as to be detachable from the cooling water pipe 231.

  The cooling water pipe unit 23 having such a structure is connected to the water supply pipe 21 and the drain pipe 22. Specifically, the internal space of the cooling water pipe 231 is connected to the secondary branch water supply pipe of the water supply pipe 21, and the space between the inner peripheral wall of the cooling plug 232 and the outer peripheral wall of the cooling water pipe 231 is the secondary of the drain pipe 22. Connected to the branch drain pipe.

  The power supply device 25 has a plus terminal (anode) 25a and a minus terminal (cathode) 25b. One end of the anode wiring 251 is electrically connected to the plus terminal 25 a (anode side) of the power supply device 25. One end of the cathode wiring 252 is electrically connected to the negative terminal 25 b (cathode side) of the power supply device 25. The other end side of the anode wiring 251 is electrically connected to the coil member 233 of each cooling water pipe unit 23. Each coil member 233 is connected in parallel by an anode wiring 251. The other end side of the cathode wiring 252 is electrically connected to the fixed mold 11 and the movable mold 12. The fixed mold 11 and the movable mold 12 are connected in parallel by the cathode wiring 252. When the cooling hole 14 is formed only in the fixed mold 11, only the fixed mold 11 is electrically connected to the cathode wiring 252. A positive terminal (anode) 25 a of the power supply device 25 is electrically connected to the coil member 233 via the anode wiring 251. The negative terminal (cathode) 25 b of the power supply device is electrically connected to the mold 10 (fixed mold 11) via the cathode wiring 252.

  Further, as shown in FIG. 2, a through hole 232 a that penetrates from the outer peripheral side to the inner peripheral side of the cooling plug 232 is formed in the cooling plug 232. A cap 235 made of an insulating resin (for example, epoxy resin) is liquid-tightly attached to the through hole 232a. The cap 235 is provided with a fine hole penetrating from the outer peripheral side to the inner peripheral side of the cooling plug 232, and the anode wiring 251 passes through the fine hole to the inner peripheral wall of the cooling plug 232 and the outer peripheral wall of the cooling water pipe 231. Has entered the space between. Thus, the tip of the anode wiring 251 that has entered the space between the inner peripheral wall of the cooling plug 232 and the outer peripheral wall of the cooling water pipe 231 is connected to the coil member 233 wound around the outer peripheral wall of the cooling water pipe 231.

  A method for cooling the mold 10 using the cooling device 20 having the above configuration will be described below.

  First, the cooling water pipe unit 231 is inserted by inserting the cooling water pipe 231 into the cooling hole part 142 of the plurality of cooling holes 14 formed in the mold 10 and screwing the cooling plug 232 into the screw hole part 141 of the cooling hole 14. 23 is fixed to the cooling hole 14. At this time, the cooling water pipe 231 is inserted into the cooling hole 142 from the tip 231a side and fixed so that the coil member 233 does not contact the side wall of the cooling hole 142. After fixing the cooling water pipe unit 23 to all the cooling holes 14, the water supply connection coupler 21a is connected to the water supply line A, and the drainage connection coupler 22a is connected to the drainage line B. Then, the cooling water is supplied from the water supply line A to the water supply pipe 21 through the water supply connection coupler 21a. The cooling water supplied to the water supply pipe 21 flows into the cooling water pipe 231 through the primary branch water supply pipe and the secondary branch water supply pipe. And cooling water is discharge | released in the cooling hole 142 from the front-end | tip 231a of the cooling water pipe | tube 231 (cooling water discharge | release process).

  The cooling water discharged into the cooling hole 142 is folded back at the bottom of the cooling hole 142 and flows from the bottom of the cooling hole 142 toward the opening (screw hole 141). In this case, since the coil member 233 is spirally wound around the outer peripheral wall of the cooling water pipe 231 so as to protrude radially outward from the outer peripheral wall, the cooling water flows along the coil member 233. Therefore, the cooling water forms a spiral flow in the cooling hole 142. That is, the coil member 233 inhibits the linear flow of cooling water from the bottom side of the cooling hole 142 to the opening side. Since the cooling water spirally flows in the cooling hole portion 142, the residence time of the cooling water in the cooling hole portion 142 is increased as compared with the case where the cooling water flows linearly. For this reason, during the operation of the mold 10, more heat of the mold 10 is taken away by the cooling water. For this reason, internal cooling efficiency improves.

  The cooling water that spirally flows between the inner peripheral wall of the cooling hole 142 and the outer peripheral wall of the cooling water pipe 231 further flows between the inner peripheral wall of the cooling plug 232 and the outer peripheral wall of the cooling water pipe 231. And it is discharged into the secondary branch drainage pipe of the drainage pipe 22. The cooling water discharged in this manner flows through the drainage line B after being joined via the primary branch drainage pipe 22 of the drainage pipe 22 and is further supplied to the cooling tower C. The cooling water supplied to the cooling tower C is cooled by the cooling tower C. The cooled cooling water is supplied to the water supply line A again.

  Further, when cooling water is discharged from the tip 231a of the cooling water pipe 231 into the cooling hole 142 (during operation of the mold), the power supply device 25 is operated. Thereby, a potential difference is generated between the mold 10 and the coil member 233. Since the mold 10 is electrically connected to the minus terminal 25b (cathode side) of the power supply device 25 and each coil member 233 is electrically connected to the plus terminal 25a (anode side) of the power supply device 25, the cooling hole The wall surface of the part 14 becomes a cathode, and the coil member 233 becomes an anode.

  Further, the portion between the inner peripheral wall surface of the cooling hole 142 and the coil member 233 is filled with the cooling water discharged from the tip 231 a of the cooling water pipe 231. In this case, when there is no potential difference between the mold 10 and the coil member 233, iron constituting the mold 10 becomes iron ions and is eluted into the cooling water (anode reaction). As the anode reaction proceeds, the cathode reaction proceeds on the wall surface of the cooling hole 14. As the anodic reaction and the cathodic reaction locally proceed simultaneously on the wall surface of the cooling hole 14, the wall surface of the cooling hole 14 is corroded.

  On the other hand, in this embodiment, when the power supply device 25 is operated, a voltage is applied between the mold 10 and the coil member 233 so that the mold 10 becomes a cathode and the coil member 233 becomes an anode. Is done. For this reason, the anticorrosion current flows from the coil member 233 toward the wall surface of the cooling hole 14. When the anticorrosive current flows, the cathode reaction is hindered and iron elution from the mold 10 (particularly the wall surface of the cooling hole 14) is suppressed. For this reason, the wall surface of the cooling hole 14 is anticorrosive (electrocorrosion process). As a result of the anticorrosion of the wall surface of the cooling hole 14, the occurrence of stress corrosion cracking of the mold 10 can be prevented.

  When designing the location of the cooling holes in the mold in consideration of stress corrosion cracking, the distance between the cavity surface and the bottom of the cooling holes must be relatively long. For example, it is assumed that an aluminum molded product is manufactured by aluminum die casting, and the life of the mold is 200,000 shots. Here, the shot number is the number of injections of the molten aluminum injected into the mold. When stress corrosion cracking is considered, if the distance between the cavity surface and the bottom of the cooling hole is less than 15 mm, the mold is likely to cause stress corrosion cracking before 200,000 shots. For this reason, conventionally, the distance between the cavity surface and the bottom of the cooling hole is set to 15 mm or more in consideration of the stress corrosion cracking. When the distance between the cavity surface and the bottom of the cooling hole is 15 mm or more, the cooling water flowing in the cooling hole cannot take the heat of the mold sufficiently, and as a result, the mold is not sufficiently cooled. . For this reason, the cooling time of a metal mold | die becomes long, and productivity falls. Therefore, in terms of productivity, it is better that the distance between the cavity surface and the bottom of the cooling hole is shorter.

  On the other hand, when the arrangement position of the cooling hole in the mold is designed without considering the stress corrosion cracking, the mold is 200,000 shots before the distance between the cavity surface and the bottom of the cooling hole is about 5 mm. Is less likely to break due to thermal stress. Therefore, as shown in the present embodiment, the position of the cooling hole in the mold is set so that the distance between the cavity surface and the bottom of the cooling hole is about 5 mm by preventing stress corrosion cracking. Can be determined. When the distance between the cavity surface and the bottom of the cooling hole is about this level, the cooling water flowing in the cooling hole can sufficiently take the heat of the mold, and the internal cooling efficiency is greatly improved. As a result, the mold is cooled in a short time, the molding cycle can be shortened, and productivity is improved.

  In addition, when the internal cooling efficiency of the mold with cooling water is improved in this way, the time required to cool the mold from the outside by applying a release material to the cavity surface of the mold (external cooling time) is shortened. Or external cooling can be abolished. Furthermore, the air blow time for removing the release material applied to the cavity surface of the mold can be shortened.

  Conventionally, as described above, the distance between the cavity surface and the bottom of the cooling hole is long, and the internal cooling efficiency of the mold is poor. Therefore, it takes a long time to solidify the molten aluminum in the cavity. For this reason, there has been a problem that the mold and aluminum react on the cavity surface and the aluminum compound sticks to the cavity surface. On the other hand, according to the present embodiment, as described above, the distance between the cavity surface and the bottom of the cooling hole can be shortened to improve the internal cooling efficiency of the mold. Time to solidify is shortened. For this reason, there is a low possibility that the mold and aluminum react with each other on the cavity surface. Therefore, it is difficult for the aluminum compound produced by the above reaction to stick to the mold. Therefore, it is possible to greatly reduce the man-hour for repairing the mold due to the aluminum compound sticking to the mold.

  Conventionally, a large amount of release material has been applied to the cavity surface in order to externally cool the mold. For this reason, the thermal shock to the cavity surface due to external cooling was large, and the life of the mold was reduced. On the other hand, according to this embodiment, since the internal cooling efficiency of the mold is good, external cooling can be abolished or the external cooling time can be shortened. For this reason, the thermal shock to the cavity surface of a metal mold | die is small, As a result, the lifetime of a metal mold | die can be extended significantly.

  As described above, according to the first embodiment, by using the coil member 233 provided in the cooling water pipe 231 inserted into the cooling hole 14 of the mold 10 as an anode for cathodic protection by an external power supply method, When the cooling water is discharged from the tip 231a of the cooling water pipe 231 to the cooling hole 142 (that is, during the operation of the mold 10), it is possible to perform the anticorrosion. And since it is possible to prevent stress corrosion cracking during the operation of the mold by means of cathodic protection, the distance between the bottom of the cooling hole 14 and the cavity surface CS can be reduced. Therefore, the internal cooling efficiency can be increased. As a result of increasing the internal cooling efficiency, the molding cycle can be shortened. Further, by applying a release agent directly to the cavity surface CS of the mold 10, external cooling for cooling the mold 10 can be eliminated or the external cooling time can be shortened. By eliminating the external cooling or shortening the external cooling time, the life of the mold can be extended.

  Further, according to the first embodiment, the coil member 233 that constitutes the anode in the anticorrosion is provided in the cooling water pipe 231, and the cooling water pipe 231 is inserted into the cooling hole 14 of the mold 10. That is, the anode is inserted into the cooling hole 14. For this reason, the entire wall surface of the cooling hole 14 can be substantially uniformly prevented from corrosion. Therefore, corrosion of the wall surface of the cooling hole 14 can be reliably suppressed, and consequently stress corrosion cracking can be reliably prevented. In addition, it is possible to prevent corrosion without mixing a rust inhibitor into the cooling water or adjusting the cooling water to be alkaline, so the mold can be used by using the water supply line and the drain line that are commonly provided in the factory. Can be cooled. For this reason, it is not necessary to provide a dedicated circulation circuit, and therefore an inexpensive and compact cooling device can be configured. Furthermore, since the coil member 233 is wound around the cooling water pipe 231 whose outer peripheral wall is formed of an electrically insulating material, the coil member 233 can be easily detached from the cooling water pipe 231. Therefore, maintenance of the coil member 233 can be easily performed.

(Second Embodiment)
In the first embodiment, the example of the cooling device that cools the mold while electrically preventing the wall of the cooling hole of the mold by the external power supply method has been described. However, in the second embodiment, the metal plating is performed by the galvanic anode method. An example of a cooling device that cools the mold while electrically protecting the wall surface of the cooling hole of the mold will be described.

  FIG. 3 is a schematic view showing a cooling device according to the second embodiment and a mold to which the cooling device is applied. The configuration of the mold 10 shown in FIG. 3 is the same as the configuration of the mold 10 shown in FIG. 1 described in the first embodiment. Therefore, among the components of the mold 10 shown in FIG. 3, the same components as those of the mold 10 shown in FIG. The configuration of the cooling device 20 shown in FIG. 3 is the same as the configuration of the cooling device 20 shown in FIG. 1 described in the first embodiment except for the configuration of the cooling water pipe unit 33. Therefore, among the components of the cooling device 20 shown in FIG. 3, the same components as those of the cooling device 20 shown in FIG.

  FIG. 4 is a schematic cross-sectional view showing a specific structure of the cooling water pipe unit 33 according to the second embodiment inserted into the cooling hole 14 provided in the fixed mold 11. As shown in FIG. 4, the cooling water pipe unit 33 includes a cooling water pipe 331, a cooling plug 332, and a coil member 333 corresponding to the protruding portion of the present invention. The cooling water pipe 331 is formed in a cylindrical shape, and its tip 331a is opened. In this embodiment, the cooling water pipe 331 is formed of an electrically insulating resin (for example, vinyl chloride resin or ABS resin).

  The cooling plug 332 is also formed in a cylindrical shape. The inner diameter of the cooling plug 332 is larger than the outer diameter of the cooling water pipe 331. A male screw is formed on the outer peripheral wall of the cooling plug 332. On the other hand, a female screw is formed on the inner peripheral wall of the screw hole 141 of the cooling hole 14 formed in the fixed mold 11 so that the cooling plug 332 can be screwed into the screw hole 141.

  Further, the cooling water pipe 331 is fixed to the cooling plug 332 so that the cooling water pipe 331 is coaxially disposed inside the cooling plug 332 and has a portion protruding from the tip of the cooling plug 332. In the present embodiment, a rib 334 is partially provided between the outer peripheral wall portion of the cooling water pipe 331 and the inner peripheral wall portion of the cooling plug 332, and the cooling water pipe 331 is fixed to the cooling plug 332 by the rib 334.

  The coil member 333 is formed of a metal material having a higher ionization tendency than the mold 10 (fixed mold 11). For example, the coil member 333 is formed of a wire formed of zinc. As shown in FIG. 4, a coil member 333 that protrudes radially outward from the outer peripheral wall of the cooling water pipe 331 is obtained by spirally winding the zinc wire around the outer peripheral wall of the cooling water pipe 331 protruding from the cooling plug 332. It is formed. The coil member 333 is preferably fixed to the cooling water pipe 331 so as to be detachable from the cooling water pipe 331.

  Further, in the first embodiment, as shown in FIG. 2, the cooling plug 232 is provided with a through hole 232a penetrating from the outer peripheral side to the inner peripheral side of the cooling plug 232, and an insulating cap 235 is provided in the through hole 232a. Although provided, in this embodiment, a configuration corresponding to the through hole 232a and the cap 235 is not provided. Further, the cooling device 20 according to the first embodiment includes the power supply device 25 as illustrated in FIG. 2, but the cooling device 20 according to the present embodiment does not include a configuration corresponding to the power supply device 25.

  A mold cooling method using the cooling device 20 having the above configuration will be described below.

  First, the cooling water pipe 331 is inserted into the cooling hole 142 of the plurality of cooling holes 14, and the cooling plug 332 is screwed into the screw hole 141 of the cooling hole 14 to fix the cooling water pipe unit 33 to the cooling hole 14. . At this time, as shown in FIG. 4, the cooling water pipe 331 is inserted into the cooling hole 142 from the tip 331a side and fixed so that the outermost peripheral portion of the spiral coil member 333 contacts the side wall of the cooling hole 142. . As a result, the coil member 333 spirally contacts the side wall of the cooling hole 142. After the cooling water pipe unit 33 is fixed to all the cooling holes 14, the cooling water is supplied to the cooling water pipe unit 33. Thereby, cooling water is discharged into the cooling hole 142 from the tip 331a of the cooling water pipe 331 (cooling water discharging step).

  The cooling water discharged into the cooling hole 142 is folded back at the bottom of the cooling hole 142 and flows from the bottom of the cooling hole 142 toward the opening (screw hole 141). In this case, since the coil member 333 is spirally wound around the outer peripheral wall of the cooling water pipe 331 so as to protrude from the outer peripheral wall, the cooling water flows along the coil member 333. Therefore, the cooling water forms a spiral flow in the cooling hole 142. That is, the coil member 333 prevents the cooling water from flowing linearly through the cooling hole 142 from the bottom side to the opening side. Since the cooling water spirally flows in the cooling hole portion 142, the residence time of the cooling water in the cooling hole portion 142 is increased as compared with the case where the cooling water flows linearly. For this reason, during the operation of the mold 10, more heat of the mold 10 is taken away by the cooling water. Therefore, the internal cooling efficiency is improved.

  In the present embodiment, the outermost peripheral portion of the coil member 333 is in contact with the side wall of the cooling hole portion 142, and a gap is formed between the outermost peripheral portion of the coil member 333 and the side wall of the cooling hole portion 142. Not. For this reason, the linear flow of the cooling water via the gap is surely prevented, and the entire amount of the cooling water in the cooling hole 142 flows spirally along the coil member 333. For this reason, the internal cooling efficiency is further improved.

  The coil member 333 is formed of a metal material whose ionization tendency is higher than the ionization tendency of the mold 10 (fixed mold 11), and the outermost peripheral part of the coil member 333 contacts the side wall of the cooling hole part 142. doing. Therefore, a battery is formed between the coil member 333 and the mold 10, and an anticorrosion current flows from a portion of the coil member 333 that is not in contact with the side wall of the cooling hole 142 toward the wall surface of the cooling hole 14. When the anticorrosive current flows, the wall surface of the cooling hole 14 is electrically anticorrosive (electrical anticorrosion step). As a result of the anticorrosion of the wall surface of the cooling hole 14, the occurrence of stress corrosion cracking of the mold 10 can be prevented.

(Modification)
FIG. 5 is a schematic cross-sectional view showing a concrete structure of a cooling water pipe unit according to a modified example of the second embodiment inserted into the cooling hole of the mold and the cooling hole. As shown in FIG. 5, the cooling water pipe unit 43 according to this example includes a cooling water pipe 431 having an open end 431a, a cooling plug 432, and a coil member 433 corresponding to the protruding portion of the present invention. The configuration of the cooling water pipe 431 and the cooling plug 432 is the same as the configuration of the cooling water pipe 231 and the cooling plug 232 shown in FIG. 2 described in the first embodiment, and a detailed description thereof will be omitted.

  The coil member 433 is formed of a metal material having a higher ionization tendency than the mold 10 (fixed mold 11), similarly to the coil member 333 illustrated in FIG. 4 described in the second embodiment. For example, the coil member 433 is formed of zinc wire. As shown in FIG. 5, a coil member 433 protruding from the outer peripheral wall of the cooling water pipe 431 is formed by spirally winding the zinc wire around the outer peripheral wall of the cooling water pipe 431 protruding from the cooling plug 432.

  One end of the electrical wiring 45 is connected to the fixed mold 11. The electrical wiring 45 enters the cooling plugs 432 through the fine holes formed in the electrically insulating caps 435 provided in the cooling plugs 432 of the cooling water pipe units 43, and then the cooling wires 432 It is connected to each coil member 433 of the water pipe unit 43. Therefore, each coil member 433 is electrically connected by the electric wiring 45 outside the mold 10 (fixed mold 11).

  Further, as shown in FIG. 5, each cooling water pipe 431 is inserted into each cooling hole 142 so that each coil member 433 provided on the outer peripheral wall does not contact the side wall of each cooling hole 142. Yes.

  Even in such a configuration, during the cooling of the mold 10, the anticorrosion is applied from the coil member 433 to the wall surface of the cooling hole 14 based on the difference in ionization tendency between the coil member 433 and the mold 10 (fixed mold 11). Current flows. For this reason, the wall surface of the cooling hole 14 is electrically protected. As a result of the anticorrosion of the wall surface of the cooling hole 14, the occurrence of stress corrosion cracking of the mold 10 can be prevented.

  As described above, according to the second embodiment, the coil members 333 and 433 provided in the cooling water pipes 331 and 431 inserted into the cooling hole 14 of the mold 10 are metals having a higher ionization tendency than the mold 10. The coil members 333 and 433 and the mold 10 are electrically connected while being formed of a material. Then, by using the coil members 333 and 433 as an anode for cathodic protection by the galvanic anode method, when cooling water is discharged from the tips of the cooling water pipes 331 and 431 to the cooling hole 142 (that is, the mold 10). During the operation of the above, an anticorrosion current flows from the coil members 333, 433 to the wall surface of the cooling hole 14, and the wall surface of the cooling hole 14 is electrically anticorrosive. In this way, stress corrosion cracking during the operation of the mold can be prevented by electric protection, so that the distance between the bottom of the cooling hole 14 and the cavity surface CS can be reduced. Therefore, the internal cooling efficiency can be increased. As a result of increasing the internal cooling efficiency, the molding cycle can be shortened. Further, by applying a release agent directly to the cavity surface CS of the mold 10, external cooling for cooling the mold 10 can be eliminated or the external cooling time can be shortened. By eliminating the external cooling or shortening the external cooling time, the life of the mold can be extended.

  Further, according to the second embodiment, the coil members 333 and 433 that form the anode in the anticorrosion are inserted into the cooling hole 14. For this reason, the entire wall surface of the cooling hole 14 can be substantially uniformly prevented from corrosion. Therefore, corrosion of the wall surface of the cooling hole 14 can be reliably suppressed, and consequently stress corrosion cracking can be reliably prevented. In addition, it is possible to prevent corrosion without mixing a rust inhibitor into the cooling water or adjusting the cooling water to be alkaline, so the mold can be used by using the water supply line and the drain line that are commonly provided in the factory. Can be cooled. For this reason, it is not necessary to provide a dedicated circulation circuit, and therefore an inexpensive and compact cooling device can be configured.

  As mentioned above, although embodiment of this invention was described, this invention should not be limited to the said embodiment. For example, in the above-described embodiment, the example in which the helical coil members 233, 333, and 433 are provided as the protruding portions on the outer peripheral walls of the cooling water pipes 231, 331, and 431 has been described. As long as it is a shape that prevents the cooling water from flowing linearly through the gap between the wall and the side wall of the cooling hole portion, it does not have to be spiral. For example, the protrusions may be formed by disk-shaped members provided at predetermined intervals in the axial direction of the cooling water pipe and connected to each other. In the above embodiment, the cooling water pipes 231, 331, and 431 are made of insulating resin. However, the cooling water pipe 231 is made by forming the pipe body from a metal material and covering the outer peripheral wall with the insulating resin. May be. In addition, the present invention can be applied to all dies that require cooling, such as a die for aluminum die casting, a casting die, and a resin die. Thus, the present invention can be modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 10 ... Mold, 11 ... Fixed type, 12 ... Movable type, 13 ... Cavity, 14 ... Cooling hole (bottomed cooling hole), 141 ... Screw hole part, 142 ... Cooling hole part, 20 ... Cooling device, 21 ... Water supply Pipe, 22 ... Drain pipe, 23, 33, 43 ... Cooling water pipe unit, 231, 331, 431 ... Cooling water pipe, 231a, 331a, 431a ... Tip, 232, 332, 432 ... Cooling plug, 233, 333, 433 ... Coil Member (protrusion), 25 ... power supply, 25a ... positive terminal (anode), 25b ... negative terminal (cathode), 251 ... anode wiring, 252 ... cathode wiring, 45 ... electrical wiring

Claims (6)

A cooling water pipe that is formed in a cylindrical shape and has a leading end that is inserted into the bottomed cooling hole formed in the mold from the tip side, and that discharges cooling water from the tip into the bottomed cooling hole;
A protrusion provided to protrude from the outer peripheral wall of the cooling water pipe;
A cathode electrically connected to the mold and an anode electrically connected to the protrusion, and cooling water is discharged from the tip of the cooling water pipe into the bottomed cooling hole. Sometimes, comprising a power supply device for applying a voltage between the mold and the protrusion ,
The protrusion is formed of a material that can be an electrode,
The mold is configured such that when the cooling water is discharged from the tip of the cooling water pipe into the bottomed cooling hole, an anticorrosion current flows from the protrusion to the wall surface of the bottomed cooling hole. Cooling system. A cooling water pipe that is formed in a cylindrical shape and has a leading end that is inserted into the bottomed cooling hole formed in the mold from the tip side, and that discharges cooling water from the tip into the bottomed cooling hole;
A protrusion provided to protrude from the outer peripheral wall of the cooling water pipe;
A mold cooling device comprising:
The protrusion is formed of a material having a higher ionization tendency than the mold, and the mold and the protrusion are electrically connected ;
The mold is configured such that when the cooling water is discharged from the tip of the cooling water pipe into the bottomed cooling hole, an anticorrosion current flows from the protrusion to the wall surface of the bottomed cooling hole. Cooling system. In the cooling device of the metal mold according to any one of claims 1 and 2 ,
A cooling device for a mold, wherein an outer peripheral wall of the cooling water pipe is formed of an electrically insulating material, and the protruding portion is spirally wound around the outer peripheral wall of the cooling water pipe. A cooling water pipe that is formed in a cylindrical shape and that has a front end that is open and has a protruding portion that protrudes from its outer peripheral wall is inserted into the bottomed cooling hole formed in the mold from the front end, and in that state, A cooling water discharge step for discharging cooling water from the tip into the bottomed cooling hole;
When the cooling water is discharged from the tip of the cooling water pipe into the bottomed cooling hole in the cooling water discharge step, the anticorrosion current is caused to flow from the protrusion to the wall surface of the bottomed cooling hole. An anti-corrosion process for anti-corrosion of the mold,
Only including,
In the anticorrosion step, a voltage is applied between the mold and the protrusion so that the mold side becomes a cathode and the protrusion becomes an anode, so that the wall surface of the bottomed cooling hole from the protrusion A method for cooling a mold, which is a process of passing a corrosion-proof current through the mold. A cooling water pipe that is formed in a cylindrical shape and that has a front end that is open and has a protruding portion that protrudes from its outer peripheral wall is inserted into the bottomed cooling hole formed in the mold from the front end, and in that state, A cooling water discharge step for discharging cooling water from the tip into the bottomed cooling hole;
When the cooling water is discharged from the tip of the cooling water pipe into the bottomed cooling hole in the cooling water discharge step, the anticorrosion current is caused to flow from the protrusion to the wall surface of the bottomed cooling hole. An anti-corrosion process for anti-corrosion of the mold,
Only including,
The protrusion is formed of a material having a higher ionization tendency than the mold;
The said anti-corrosion process is a mold cooling method which is a process of flowing an anti-corrosion electric current from the said protrusion part to the wall surface of the said bottomed cooling hole by electrically connecting the said metal mold | die and the said protrusion part. In the cooling method of the metal mold according to claim 4 or 5 ,
A cooling method for a mold, wherein an outer peripheral wall of the cooling water pipe is formed of an electrically insulating material, and the projecting portion is spirally wound around the outer peripheral wall of the cooling water pipe.

Images