RESIN FILLING METHOD

A resin filling method that includes the steps of filling in a filling step the filling clearance with the molten resin pressurized by the pressurizing unit, through the first flow path and the second flow path, with the laminated core being held between the flow path plate in contact with the upper mold and the lower mold; moving the upper mold and the pressurizing unit up with respect to the flow path plate to create a space between the upper mold and the flow path plate; removing residual resin in a resin removing step remaining in the second flow path in the flow path plate, with the flow path plate being located on the laminated core; and moving in a core removing step the flow path plate up from the laminated core and then removing the laminated core from the lower mold.

BACKGROUND

The present disclosure relates to resin filling methods for filling filling clearances, which are formed by placing magnets in placement holes of a laminated core of a rotating electrical machine rotor, with resin.

A technique of forming placement holes in a laminated core that is a stack of a plurality of electrical steel sheets and filling clearances formed by placing magnets in the placement holes with a thermosetting resin is known as a technique of manufacturing a rotor for use in rotating electrical machines. For example, Japanese Patent Application Publication No. 2011-88329 discloses a resin sealing device using an injection molding method. Japanese Patent Application Publication No. 2011-88329, a core is held between a lower mold unit and an upper mold unit, and clearances each formed between a space accommodating the core and a magnet are filled with molten resin. In the upper mold unit, a third lifting plate having a position restricting tube that restricts the position of the outer peripheral surface of the core is attached at a position below a first lifting plate and a second lifting plate of the upper mold unit having a spool bushing through which molten resin flows, such that the third lifting plate can hang from the first and second lifting plates via support rods. When the upper mold unit is moved downward toward the lower mold unit, the position restricting tube of the third lifting plate restricts the position of the core placed on the lower mold unit, so that the core is held between the lower mold unit and the upper mold unit.

SUMMARY

In the resin sealing device of Japanese Patent Application Publication No. 2011-88329, when the third lifting plate is moved upward from the core after the clearances in the core are filled with the resin, the resin remaining in a resin flow path in the third lifting plate is separated from the resin filling the clearances in the core. At this time, there is nothing that prevents lifting of the core from the lower mold unit. That is, since the resin remaining in the flow path connects to the resin filling the clearances in the core, the core may be lifted from a lower mold when the third lifting plate is moved upward.

There is a possibility that, with the core being lifted from the lower mold, the resin remaining in the flow path in the third lifting plate may be separated from the resin filling the clearances in the core. In this case, the core may be flawed when the lifted core drops.

An exemplary aspect of the disclosure provides a resin filling method by which residual resin can be removed while preventing lifting of a laminated core and which can thus prevent flaws on the laminated core.

According to an aspect of the present disclosure, a resin filling method for filling a filling clearance formed by an inner wall surface of a placement hole formed in a laminated core of a rotating electrical machine rotor in a direction of a central axis of the laminated core and a magnet placed in the placement hole, wherein the resin filling method utilizes an upper mold that has a first flow path, a pressurizing unit that is coupled to the upper mold and that introduces pressurized molten resin into the first flow path; a flow path plate that has a second flow path for guiding the molten resin from the first flow path into the filling clearance, that is located below the upper mold, and that can be moved up and down relative to the upper mold; and a lower mold on which the laminated core is placed. The method includes the steps of filling in a filling step the filling clearance with the molten resin pressurized by the pressurizing unit, through the first flow path and the second flow path, with the laminated core being held between the flow path plate in contact with the upper mold and the lower mold; moving the upper mold and the pressurizing unit up with respect to the flow path plate to create a space between the upper mold and the flow path plate; removing residual resin in a resin removing step remaining in the second flow path in the flow path plate, with the flow path plate being located on the laminated core; and moving in a core removing step the flow path plate up from the laminated core and then removing the laminated core from the lower mold.

In the above resin filling method, the residual resin remaining in the second flow path in the flow path plate is separated from the resin filling the filling clearance of the laminated core, while preventing lifting of the laminated core by the flow path plate.

According to the resin filling method, the residual resin can thus be removed while preventing lifting of the laminated core, and flaws on the laminated core can be prevented.

DETAILED DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the above resin filling method will be described below.

First, specific functions and effects of the above resin filling method will be described.

In the resin filling method, in the filling step, the laminated core is held between the flow path plate having the upper mold located thereon and the lower mold, and the filling clearance is filled with the molten resin pressurized by the pressurizing unit through the first flow path and the second flow path. At this time, the filling clearance is filled with the resin and the residual resin, which is an unwanted part of the resin, remains in the first flow path and the second flow path.

Thereafter, in the resin removing step, the upper mold and the pressurizing unit are moved upward, and with the flow path plate being located on the laminated core, the residual resin remaining in the second flow path in the flow path plate is removed. Specifically, when the upper mold and the pressurizing unit are moved upward, the flow path plate is moved downward relative to the upper mold and the pressurizing unit, creating a space between the upper mold and the flow path plate. The residual resin remaining in the second flow path is removed to the outside by using the space between the upper mold and the flow path plate.

At this time, since the flow path plate is located on the laminated core, the residual resin remaining in the second flow path can be separated from the resin filling the clearance in the laminated core while preventing lifting of the laminated core by the flow path plate. The laminated core placed on the lower mold can thus be prevented from being lifted in the direction of the central axis of the laminated core, and the residual resin remaining in the second flow path can be separated from the resin filling the filling clearance in the laminated core. Since the laminate core is not lifted and therefore does not drop, flaws on the laminated core can be prevented.

Subsequently, in the core removing step, the upper mold and the pressurizing unit are further moved upward to lift the flow path plate from the laminated core, and the laminated core is then removed from the lower mold.

In the resin filling method, the first flow path may be formed so that its flow-path sectional area increases toward a lower end of the first flow path.

In this case, the residual resin remaining in the first flow path whose flow-path sectional area increases toward the lower end of the first flow path connects to the residual resin remaining in a horizontal flow path portion of the second flow path. The residual resin remaining in the first flow path can be easily removed in this connected state from the first flow path when the upper mold and the pressurizing unit are moved upward.

The second flow path may have the horizontal flow path portion that is formed in an upper surface of the flow path plate so as to connect to the first flow path, and a gate flow path portion that is formed so as to connect to the horizontal flow path portion and so that its flow-path sectional area decreases toward a lower end of the gate flow path portion, and that faces the filling clearance at its lower opening end.

In this case, since the flow-path sectional area of the gate flow path portion of the second flow path decreases toward the lower end of the gate flow path portion, the residual resin remaining in the second flow path can be easily removed with the upper mold and the pressurizing unit in the lifted state. The residual resin remaining in the gate flow path portion can be easily separated at the lower opening end of the gate flow path portion from the surface of the resin filling the filling clearance of the laminated core.

A plurality of the placement holes may be formed in a radial pattern about the central axis of the laminated core. The second flow path in the flow path plate may guide the molten resin into the filling clearance formed in one or more of the plurality of placement holes. The resin filling method may use a relative rotation mechanism that rotates at least the flow path plate and the lower mold relative to each other about the central axis of the laminated core placed on the lower mold, and that selects the one or more of the plurality of placement holes as selected placement holes and sequentially causes the selected placement holes to face the second flow path in the flow path plate. In the filling step, the filling clearance in any of the selected placement holes may be filled with the molten resin through the second flow path in the flow path plate. In the resin removing step, the residual resin remaining in the second flow path may be removed. An indexing step of changing the selected placement holes to the placement holes that have not been filled with the molten resin by the relative rotation mechanism may be performed after the resin removing step and before the core removing step. The filling step and the resin removing step may then be performed again.

In this case, at least the flow path plate and the lower mold are rotated relative to each other by a predetermined angle by the relative rotation mechanism, whereby filling with the molten resin and removal of the residual resin can be performed for a predetermined number of selected placement holes of the laminated core at a time. With this configuration, a pressure that is applied to the molten resin when the filling clearance in each selected placement hole is filled with the molten resin can be easily increased as compared to the case where the filling clearances in all the placement holes are simultaneously filled with the molten resin. This configuration can thus enhance efficiency in filling the filling clearance with the molten resin and can reduce the size of the pressurizing unit and can thus reduce the size of a device that is used in the resin filling method.

Embodiments

Embodiments of a resin filling method will be described with reference to the accompanying drawings.

First Embodiment

In the resin filling method of the present embodiment, as shown inFIG. 1, magnets82are placed in placement holes81extending in the direction L of the central axis of a laminated core8of a rotating electrical machine rotor, and filling clearances83each created between the inner wall surface of the placement hole81and the magnet82are filled with resin7. A resin filling device1including an upper mold2, a pressurizing unit3, a flow path plate4, and a lower mold5is used in the resin filling method. The upper mold2has a first flow path21into which molten resin7is introduced from the pressurizing unit3. The pressurizing unit3is coupled to the upper part of the upper mold2and introduces the pressurized molten resin7into the first flow path21. The flow path plate4is located below the upper mold2and can be moved up and down relative to the upper mold2. The flow path plate4of the present embodiment is attached such that it can hang down from the upper mold2. The flow path plate4has a second flow path41through which the molten resin7is introduced from the first flow path21into the filling clearances83. The laminated core8is placed on the lower mold5, and the lower mold5holds the laminated core8between the lower mold5itself and the upper mold2and the flow path plate4.

In the resin filling method, a filling step, a resin removing step, and a core removing step are performed to fill the filling clearances83in the placement holes81of the laminated core8with the molten resin7.

In the filling step, as shown inFIG. 1, the laminated core8is sandwiched between the flow path plate4in contact with the upper mold2and the lower mold5, and the filling clearances83are filled with the molten resin7pressurized by the pressurizing unit3through the first flow path21and the second flow path41. In the resin removing step, as shown inFIG. 2, the upper mold2and the pressurizing unit3are lifted from the flow path plate4to create a space S between the upper mold2and the flow path plate4. Thereafter, with the flow path plate4, which hangs down from the upper mold2, being located on the laminated core8, residual resin71remaining in the second flow path41of the flow path plate4is removed. In the core removing step, as shown inFIG. 3, after the upper mold2and the pressurizing unit3are further lifted and the flow path plate4is lifted from the laminated core8, the laminated core8is removed from the lower mold5.

The resin filling device1etc. used in the resin filling method of the present embodiment will be described first.

The rotating electrical machine rotor of the present embodiment is an inner rotor that is placed near the inner periphery of a stator and rotates relative to the stator. The laminated core8is formed by a plurality of electrical steel sheets80stacked in the direction L of the central axis of the laminated core8. As shown inFIG. 4, the laminated core8has the plurality of placement holes81formed in a radial pattern about the central axis of the laminated core8. Each placement hole81is formed so as to extend through the plurality of electrical steel sheets80. The laminated core8further has a central hole84in the center which extends in the direction L of the central axis of the laminated core8. The magnets (permanent magnets)82placed in the placement holes81are fixed to the laminated core8with the resin7filling the filling clearances83.

The resin is7is a thermoplastic resin that becomes soft and pliable when heated and hardens when cooled. Resin filling methods for conventional rotating electrical machine rotors use a thermosetting resin to fix the magnets82in the placement holes81as heat resistance is prioritized. However, the resin filling method of the present embodiment uses a thermoplastic resin that can ensure heat resistance. Preferably, the thermoplastic resin is liquid crystal polyester (LCP) that is a highly heat-resistant liquid crystal polymer.

As shown inFIG. 1, the lower mold5is attached to the upper surface of a bed11, and the upper mold2is attached to the lower surface of a lifting base12that is moved up and down relative to the bed11. The pressurizing unit3is attached to the lifting base12such that the axis of a screw32extends in the up-down direction (vertical direction). The lifting base12is moved up and down by a lifting mechanism, not shown. A positioning collet51, which is inserted in the central hole84of the laminated core8to position the laminated core8with respect to the lower mold5, is disposed in the lower mold5so as to project upward beyond the lower mold5.

The pressurizing unit3has a cylinder31that stores and heats the resin7, the screw32placed in the cylinder31such that the screw32can rotate and slide therein, and a hopper33that supplies solid resin7into the cylinder31. The cylinder31is provided with a heater311, and the screw32has a helical projection321on its outer peripheral surface. The solid resin7supplied from the hopper33into the cylinder31is melted by heating with the heater311of the cylinder31, and the molten resin7is pressurized by the helical projection321of the screw32and ejected into the first flow path21of the upper mold2.

As shown inFIG. 1, the upper mold2has embedded therein a spool bushing22that has the first flow path21formed therein, and a cooler23that cools the molten resin7ejected from the pressurizing unit3into the first flow path21. The first flow path21is formed so that its flow-path sectional area increases toward the lower end of the first flow path21. The cooler23may be embedded in the flow path plate4or the lower mold5depending on fluidity of the resin7.

Hanging rods43that allow the flow path plate4to hang down from the upper mold2are disposed in the upper mold2so as to extend downward. The flow path plate4has insertion holes42through which the hanging rods43are inserted, and each hanging rod43has a catch-and-hold portion431near its lower end which catches and holds the flow path plate4.

A blocking plate34that can block the first flow path21in the spool bushing22is placed between the lower end of the cylinder31and the spool bushing22. The blocking plate34is withdrawn from the first flow path21when the molten resin7is to be introduced into the first flow path21, and blocks the first flow path21when introduction of the molten resin7into the first flow path21is to be stopped. When the filling clearances83are filled with the resin7, the first flow path21is blocked with the blocking plate34to separate the residual resin71remaining in the first flow path21from the resin7in the cylinder31.

The second flow path41in the flow path plate4is formed by a horizontal flow path portion411and a plurality of gate flow path portions412. The horizontal flow path portion411is formed in the shape of a groove in the upper surface of the flow path plate4so as to connect to the first flow path21. When the upper surface of the flow path plate4is mated with the lower surface of the upper mold2, the horizontal flow path portion411forms a flow path through which the molten resin7flows. The horizontal flow path portion411is shaped such that the first flow path21communicates with the plurality of gate flow path portions412through the horizontal flow path portion411.

As shown inFIG. 1, the gate flow path portions412extend from the upper surface of the flow path plate4to the lower surface thereof so as to connect to the horizontal flow path portion411. Each gate flow path portion412is formed so that its flow-path sectional area decreases toward the lower end of the gate flow path portion412. Each gate flow path portion412has the smallest flow-path sectional area at its lower opening end, and the lower opening end of each gate flow path portion412faces the filling clearance83. The number of gate flow path portions412is the same as that of filling clearances83.

The second flow path41in the flow path plate4of the present embodiment is formed so that the first flow path21communicates with the plurality of filling clearances83in the laminated core8through the second flow path41. The molten resin7is simultaneously supplied from the first flow path21into the plurality of filling clearances83.

As shown inFIG. 3, when the upper mold2and the pressurizing unit3are withdrawn to an upper position, the flow path plate4hangs, by its own weight, from the upper mold2via the hanging rods43. When the upper mold2and the pressurizing unit3are moved downward toward the laminated core8, the flow path plate4is placed on the laminated core8, and the upper mold2and the pressurizing unit3are moved downward until the upper mold2is located on the flow path plate4. Thrust of the lifting base12is applied via the upper mold2and the flow path plate4to the laminated core8placed on the lower mold5, and the laminated core8is thus held between the flow path plate4and the lower mold5.

As shown inFIG. 2, when the upper mold2and the pressurizing unit3are moved upward away from the laminated core8, the flow path plate4remains on the laminated core8until the flow path plate4is caught and held by the catch-and-hold portions431of the hanging rods43. As shown inFIG. 3, when the upper mold2and the pressurizing unit3are further moved upward and the flow path plate4is caught and held by the catch-and-hold portions431of the hanging rods43, the flow path plate4is separated from the laminated core8and is moved upward with the upper mold2and the pressurizing unit3.

Next, the resin filling method of the present embodiment will be described in detail.

In the resin filling method, with the flow path plate4being placed on the laminated core8to prevent lifting of the laminated core8, the residual resin71remaining in the second flow path41in the flow path plate4is separated from the resin7filling the filling clearances83in the laminated core8.

Specifically, in a preparation step, the laminated core8is first placed on the lower mold5so that the positioning collet51in the lower mold5is inserted into the central hole84of the laminated core8. The magnets82are placed in the plurality of placement holes81in the laminated core8. At this time, the magnet82are positioned in each placement core81as appropriate to form the filling clearance83between the inner wall surface of each placement hole81and the outer wall surface of each magnet82.

In the pressurizing unit3, solid resin7is introduced from the hopper33into the cylinder31, and the resin7is heated and melted with the heater311of the cylinder31. At this time, the lifting base12provided with the upper mold2, the pressurizing unit3, and the flow path plate4is located at a lifted position. Subsequently, in the filling step, the lifting base12is moved downward by the lifting mechanism so that the upper mold2, the pressurizing unit3, and the flow path plate4become closer to the laminated core8. The flow path plate4is thus placed on the laminated core8, the upper mold2contacts the flow path plate4, and the laminated core8is held between the flow path plate4having the upper mold2located thereon and the lower mold5due to thrust of the lifting mechanism.

Thereafter, as shown inFIG. 1, the screw32of the pressurizing unit3is rotated to supply the molten resin7in the cylinder31into the first flow path21in the upper mold2. The blocking plate34is withdrawn in advance from the first flow path21. The molten resin7thus supplied into the first flow path21flows from the first horizontal flow path portion411to the gate flow path portions412of the second flow path41and fills the filling clearances83in the placement holes81through the gate flow path portions412. When flowing through the first flow path21, the molten resin7is cooled by the cooler23embedded in the upper mold2. The filling clearances83are thus filled with the resin7and the residual resin71, which is an unwanted part of the resin7, remains in the first flow path21and the second flow path41. After the filling clearances83are filled with the resin7, the first flow path21is blocked by the blocking plate34.

Subsequently, after the resin7in the filling clearances83and the flow paths21,41hardens, the resin removing step is performed as shown inFIG. 2. Namely, the lifting base12is moved upward by the lifting mechanism to such a predetermined position that the flow path plate4is not separated from the laminated core8. At this time, with the flow path plate4remaining on the laminated core8, the upper mold2and the pressurizing unit3are moved upward to create the space S between the upper mold2and the flow path plate4. The residual resin71remaining in the first flow path21whose flow-path sectional area increases toward the lower end of the first flow path21connects to the residual resin71remaining in the horizontal flow path portion411of the second flow path41, and is removed in this connected state from the first flow path21when the upper mold2is lifted from the flow path plate4.

At this time, more specifically, the residual resin71remaining in the first flow path21has been separated from the resin7in the cylinder31by the blocking plate34. When the residual resin71remaining in the first flow path21hardens, the residual resin71contracts in such a direction that the residual resin71separates from the tapered inner wall surface of the first flow path41. The residual resin71remaining in the first flow path21is thus easily removed from the first flow path21. The residual resin71remaining in the first flow path21is exposed such that the residual resin71projects upward with respect to the upper surface of the flow path plate4.

Subsequently, as shown inFIG. 2, the residual resin71that had remained in the first flow path21is held by an unloading device13by using the space S between the upper mold2and the flow path plate4, and the residual resin71remaining in the second flow path41is removed from the second flow path41. When the resin7hardens, the residual resin71remaining in each gate flow path portion412of the second flow path41whose flow-path sectional area decreases toward the lower end of the gate flow path portion412contracts in such a direction that the residual resin71separates from a part of the tapered inner wall surface of the gate flow path portion412which is located on the radially outer side of the laminated core8. The residual resin71thus adheres to a part of the tapered inner wall surface of each gate flow path portion412which is located on the radially inner side of the laminated core8. Accordingly, at the lower opening ends of the gate flow path portions412, the residual resin71can be easily separated from the surface of the resin7filling the filling clearances83in the laminated core8.

As described above, the residual resin71remaining in the first flow path21is held by the unloading device13and the entire residual resin71remaining in the first flow path21and the second flow path41is lifted by the unloading device13, whereby the entire residual resin71remaining in the first flow path21and the second flow path41is separated from the surface of the resin7filling the filling clearances83in the laminated core8. The entire residual resin71can thus be easily removed.

When the residual resin71remaining in the gate flow path portions412of the second flow path41is separated from the resin7filling the filling clearances83, the flow path plate4is located on the laminated core8, which prevents lifting of the laminated core8. Since the laminated core8is not lifted and therefore does not drop, flaws on the laminated core8can be prevented. Moreover, when the residual resin71is separated from the resin7, the laminated core8placed on the lower mold5is less likely to be displaced in the direction L of the central axis of the laminated core8.

Furthermore, when the residual resin71is separated from the resin7filling the filling clearances83, the surface of the resin7filling the filling clearances83can be pressed by the flow path plate4. The resin7filling the filling clearances83is thus less likely to have a rough surface (separation surface).

Subsequently, as shown inFIG. 3, in the core removing step, the lifting base12is further moved upward by the lifting mechanism. The upper mold2and the pressurizing unit3are thus further moved upward, and the flow path plate4is caught and held by the catch-and-hold portions431of the hanging rods43, so that the flow path plate4is lifted by the hanging rods43and hangs, by its own weight, from the upper mold2. After the flow path plate4is separated upward from the laminated core8, the laminated core8is removed from the lower mold5by removing the positioning collet51from the central hole84of the laminated core8.

As described above, according to the resin filling method of the present embodiment, the residual resin71can be removed while preventing lifting of the laminated core8, and flaws on the laminated core8can be prevented.

Second Embodiment

In a resin filling method of the present embodiment, the filling clearances83in the plurality of placement holes81are sequentially filled with the resin7by filling a predetermined number of filling clearances83with the resin7at a time, instead of simultaneously filling all of the filling clearances83in the plurality of placement holes81of the laminated core8with the resin7.

As shown inFIG. 5, the second flow path41in the flow path plate4of the present embodiment guides the molten resin7into the filling clearances83in a predetermined number of placement holes81out of the plurality of placement holes81in the laminated core8. The resin filling device1that is used in the resin filling method of the present embodiment has a relative rotation mechanism6that rotates the lower mold5by predetermined angles according to predetermined intervals in the circumferential direction about the central axis of the laminated core8at which the plurality of placement holes81are formed.

The relative rotation mechanism6rotates the lower mold5relative to the upper mold2, the pressurizing unit3, and the flow path plate4about the central axis of the laminated core8placed on the lower mold5such that each of a predetermined number of placement holes81, namely selected placement holes81A, sequentially faces the gate flow path portion412of the second flow path41in the flow path plate4.

The selected placement holes81A of the present embodiment are two placement holes81that are located adjacent to each other. In order to reduce the flow path length of the horizontal flow path portion411of the second flow path41, the pressurizing unit3is located at a position offset in the radial direction of the laminated core8from the position facing the central part of the laminated core8. The pressurizing unit3may be positioned so as to face the central part of the laminated core8.

The selected placement holes81A may be determined in various patterns as long as the selected placement holes81A are a predetermined number of placement holes81out of the plurality of placement holes81. For example, the selected placement holes81A may not be a predetermined number of placement holes81that are located adjacent to each other, but may be a predetermined number of placement holes81located on both sides in the radial direction of the central axis of the laminated core8. For example, the plurality of placement holes81may be divided into two to four groups, and the placement holes81, one from each group, may be determined as the selected placement holes81A.

The relative rotation mechanism6may not rotate the lower mold5, but may rotate the flow path plate4, or the upper mold2, the pressurizing unit3, and the flow path plate4, relative to the lower mold5by predetermined angles.

In the resin filling method of the present embodiment, the filling step and the resin removing step are repeatedly performed for each group of a predetermined number of placement holes81, thereby filling all of the filling clearances83with the molten resin7. After the resin removing step and before the core removing step, an indexing step is performed to change the selected placement holes81A to those placement holes81which have not been filled with the molten resin7by the relative rotation mechanism6.

First, as shown inFIG. 5, in the filling step, the filling clearances83in a predetermined number of first selected placement holes81A are filled with the molten resin7through the second flow path41in the flow path plate4. Next, as shown inFIG. 6, in the resin removing step, with the flow path plate4remaining on the laminated core8, the upper mold2and the pressurizing unit3are moved upward to a predetermined position. The residual resin71remaining in the first flow path21and the entire second flow path41is removed by using the space S created between the upper mold2and the flow path plate4.

Thereafter, in the indexing step, the lower mold5is rotated by the predetermined angle by the relative rotation mechanism6to change the selected placement holes81A from the first selected placement holes81A to second selected placement holes81A that have not been filled with the molten resin7. Subsequently, the filling step is performed again to fill the filling clearances83of the predetermined number of second selected placement holes81A with the molten resin7through the second flow path41in the flow path plate4. The resin removing step is then performed again. Namely, with the flow path plate4remaining on the laminated core8, the upper mold2and the pressurizing unit3are moved upward to the predetermined position. The residual resin71remaining in the first flow path21and the entire second flow path41is removed by using the space S created between the upper mold2and the flow path plate4.

The filling step, the resin removing step, and the indexing step can be performed the number of times corresponding to the number of groups of the placement holes81. After the filling clearances83in all the placement holes81are filled with the resin7and the residual resin71remaining in the first flow path21and the entire second flow path41is removed, the core removing step is performed in which the laminated core8is removed from the lower mold5.

In the present embodiment, relative rotation between the lower mold5and the upper mold2, the pressurizing unit3, and the flow path plate4by the predetermined angle is made by the relative rotation mechanism6, whereby a predetermined number of selected placement holes81A of the laminated core8can be filled with the molten resin7at a time and the residual resin71can be removed. With this configuration, the pressure that is applied to the molten resin7when the filling clearance83in each selected placement hole81A is filled with the molten resin7can be easily increased as compared to the case where the filling clearances83in all the placement holes81are simultaneously filled with the molten resin7. This configuration can thus enhance efficiency in filling the filling clearances83with the molten resin7and can reduce the size of the pressurizing unit3and can thus reduce the size of the resin filling device1.

In the present embodiment, other configurations and the components denoted by the same reference characters in the figures as the first embodiment are similar to those of the first embodiment, and functions and effects of the present embodiment are similar to those of the first embodiment.

In the first and second embodiments, the magnets82are placed in the placement holes81after the laminated core8is placed on the lower mold5. However, after the laminated core8are placed on a loading plate-like pallet and the magnets82are placed in the placement holes81in the laminated core8, the plate-like pallet may be carried so as to be placed on the lower mold5.

In the first and second embodiments, the flow path plate4can hang, by its own weight, from the upper mold2and is placed on the surface of the laminated core8. However, the flow path plate4may be attached so that it can be moved up and down with respect to the lower mold5by a lifting mechanism mounted on the lower mold5. Alternatively, the flow path plate4may be attached so that it can be moved up and down with respect to the upper mold2by a lifting mechanism mounted on the upper mold2. In these cases, when the residual resin71remaining in the second flow path41in the flow path plate4is removed from the second flow path41, the laminated core8may be pressed downward by the lifting mechanism mounted on the lower mold5or the upper mold2.

The first and second embodiments are described with respect to the case where the pressurizing unit3serving as a single screw cylinder is used. However, a plurality of pressurizing units3may be mounted on the upper mold2.

The resin filling methods described in the first and second embodiments are injection molding methods using the resin7that is a thermoplastic resin. Accordingly, the molten resin7can be stored in the pressurizing unit3. According to the resin filling methods described in the first and second embodiments, loss of the resin material can therefore be reduced as compared to conventional common resin filling methods using a thermosetting resin, and running cost of the resin filling device1can be reduced.

In the case of using a thermosetting resin to fill the laminated core8, a tablet material is commonly used which has a size corresponding to the amount of thermosetting resin that is used to fill the laminated core8. Accordingly, a plurality of types of thermosetting resin tablet materials need to be prepared in order to fill laminated cores8of a plurality of sizes with a thermosetting resin. However, in the case of using a thermoplastic resin to fill the laminated core8, a granular material can be commonly used. The thermoplastic resin can therefore be flexibly used for laminated cores8of a plurality of sizes.