JP4900097B2 - Stator core molding method - Google Patents

Description

  The present invention relates to a resin molding method for resin-sealing a stator for a motor.

A method of manufacturing a stator core is known by laminating steel plates punched by press working to form a stator core and injection-molding resin in a state where windings are assembled.
For example, a “molding die” described in Patent Document 1 can be cited.
As shown in FIG. 7, the entire stator in which the winding 102 is applied to the stator core 101 made of a laminated plate is inserted into a molding cavity 103 to form a molding space surrounding the entire stator and resin molded. In that case, in order to form a molding space surrounding the winding portion with the mold and the stator core, a restricting means such as a stopper is provided to stop the mold at an appropriate position.

Japanese Patent Laid-Open No. 05-236713

In the invention disclosed in Patent Document 1, since the entire stator core is covered with resin, there is a problem that the whole becomes large. Hybrid motor drive motors are particularly problematic because of the strong demand for miniaturization. The present applicant has applied for a method of reducing the size of the entire motor by sandwiching a stator core made of a laminated plate material between upper and lower molds and using the laminated plate material as a part of the mold to form a molding cavity. Proposed in 2007-003675.
Although not clearly described in this application specification, the upper and lower molds are expensive. Therefore, when the laminated stator core is below the reference value, as shown in FIG. In order to prevent the molds 105 and 106 from being damaged due to the contact with the 106, stoppers 107 and 108 for limiting the lowest lowered position of the upper mold 105 which is a movable mold have been installed.

However, when the thickness of the laminated stator core is equal to or less than the reference value, if the upper die 105 is stopped by the stoppers 107 and 108, a gap C is formed between the upper die 105 and the stator core 101 as shown in FIG. There was a risk of resin leakage from the gaps formed. Then, the resin leaks into the gap between the upper mold 105 and the stator core 101 to form a thin resin skin. When the bolt is fastened with the resin thin skin sandwiched, there is a risk that sufficient tightening torque cannot be obtained.
Although a method of inspecting whether a thin resin skin is formed by visual inspection or the like in a subsequent process is also conceivable, there is a problem that costs increase.
On the other hand, the thickness of the laminated plate material is sufficiently checked before being inserted into the injection molding machine, and the thickness of the stator core 101 is hardly considered to be below the reference value.

  However, from the viewpoint of a manufacturer pursuing safety, in the unlikely event that there is a check omission, there is a concern that a motor without sufficient tightening torque will be shipped. The present applicant has made the present invention to avoid such an emergency.

  The present invention has been made in view of the above circumstances, and in the unlikely event that the thickness of a stator core made of a laminated plate material is below a reference value, the stator core does not abnormally stop the injection molding machine and take out defective products to the subsequent process An object is to provide a forming method.

In order to achieve the above object, the stator core molding method of the present invention has the following configuration.
(1) In a stator core molding method in which a stator core made of a laminated plate material is sandwiched between upper and lower molds to form a molding cavity, and a resin is injection molded into the molding cavity, between the upper and lower molds forming a resin injection passage to the molding cavity When the thickness of the stator core is below the standard, the upper and lower molds should be the smallest part. Abut.

(2) In the stator core molding method described in (1), an abnormality is detected when resin injection is not completed.
Here, incomplete resin injection means that if a predetermined amount of resin is not injected within a predetermined time from the start of resin injection, the resin injection is performed in a time shorter than the predetermined time from the start of resin injection. It can be detected when it has ended.
(3) In the stator core molding method described in (1) or (2), the minimum portion is formed immediately before the molding cavity.

Next, the operation and effect of the stator core molding method of the present invention having the above configuration will be described.
According to the stator core molding method described in (1), in a stator core molding method in which a stator core made of a laminated plate material is sandwiched between upper and lower molds to form a molding cavity, and resin is injection molded into the molding cavity. When the minimum part of the distance between the upper and lower molds is provided in the gap between the upper and lower molds forming the resin injection path, and the minimum part extends over the entire circumference of the resin injection path leading to the molding cavity, and the thickness of the stator core is below the reference In addition, since the upper and lower molds come into contact with each other at the minimum part, if the stator core thickness is less than the standard value, the upper and lower molds come into contact with each other at the minimum part. Even if a molding failure occurs due to insufficient resin and a thin resin skin occurs on the stator core, the product itself can be excluded as a defective product. That. Since the minimum portion extends over the entire circumference of the resin injection passage leading to the molding cavity, the resin flow can be completely blocked.

According to the stator core molding method described in (2), since an abnormality is detected when resin injection is not completed, the injection molding machine detects an abnormality without checking molding defects, so that the thickness of the stator core Can be reliably eliminated.
If the thickness of the stator core made of the laminated plate material is within the reference value, the gap distance between the minimum portions of the upper and lower molds is designed to be 0.5 mm to 0.8 mm. On the other hand, when the gap at the minimum portion is 0.2 mm or less, the resin flow becomes poor, and the resin pressure in the molding cavity does not rise to a predetermined value within a predetermined time. Since the resin pressure in the molding cavity is measured with a pressure gauge, if the pressure measured with the pressure gauge does not reach a predetermined value even after a predetermined time has elapsed, an abnormality is detected and a control device for the injection molding machine An abnormality is reported. According to this method, since an abnormality can be detected without bringing the minimum parts of the upper and lower molds into contact with each other, damage to expensive molds can be reduced.
As another abnormality detection method, when the minimum part comes into contact, the injection of the resin is stopped halfway. Therefore, it can be determined that the abnormality is detected even when the injection of the resin is stopped before a predetermined time elapses. An abnormality can also be detected when the resin injection is not completed when a predetermined time has elapsed and when a predetermined amount of resin is not injected within a predetermined time after the resin injection is started.

  According to the stator core molding method described in (3), since the minimum portion is formed immediately before the molding cavity, the minimum portion is located at the boundary between the winding mold portion and the unnecessary portion to be removed from the product. Therefore, the unnecessary part can be easily removed. That is, when the mold is opened and the product is taken out, it can be easily broken at the minimum portion, so that unnecessary portions can be easily removed.

  Hereinafter, an embodiment embodying a stator molding method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view showing the main configuration of a resin molding apparatus 1 in this embodiment. The resin molding apparatus 1 includes an upper die 3 and a lower die 4 (FIG. 1 shows a die-closed state) and a lower die 4 which are closed and opened with each other in order to seal the motor stator 2 as a workpiece. Are provided with a base 5 and upper and lower eject plates 6 and 7. The stator 2 is manufactured by attaching the winding 9 to the stator core 8 in advance.

  The upper mold 3 is provided so as to be movable in the vertical direction by a predetermined actuator (not shown). For example, a hydraulic cylinder or an air cylinder is used as the actuator. The upper mold 3 includes a thick plate-like base frame 10 and a mold member 11 assembled to the base frame 10. The base frame 10 is composed of two metal blocks 12 and 13 combined with each other. A concave portion 14 forming a cavity K (see FIGS. 2 and 3) is formed below the mold member 11. At the center of the mold member 11, a resin injection port 15 for injecting resin into the cavity K is formed corresponding to the axial center position of the stator 2. The resin injection port 15 opens to the recess 14 and is formed perpendicular to the recess 14 and has a substantially conical shape. The base frame 10 is provided with a resin passage 16 that communicates with the resin injection port 15. Resin is supplied to the resin passage 16 from outside at high pressure. The resin supplied to the resin passage 16 is injected into the cavity K from the resin injection port 15.

  FIG. 2 is a sectional view showing portions of the mold member 11 and the center post 30 in a state where the upper mold 3 and the lower mold 4 are closed. A lock portion 31 b that protrudes from the upper surface of the center post 30 is provided at the tip of the spool lock pin 31. The lock portion 31b has a shape in which a plurality of bulges are connected. The lock portion 31b is disposed so as to protrude into the resin injection port 15 of the mold member 11 when the mold is closed. The lock portion 31b is used to bite and lock (fasten) the resin solidified at the resin injection port 15 after resin molding, and corresponds to the fastening means of the present invention. As shown in FIG. 2, the tip end surface of the cylindrical spool eject pin 27 </ b> A in the standby state is flush with the upper surface of the center post 30. Further, as shown in FIG. 2, the upper end surface of the spool eject pin 27 in the standby state is disposed slightly immersed in the pin hole 25 d from the upper surface of the center post 30.

  As shown in FIG. 2, in the mold closed state, a gap 33 serving as a passage for the resin supplied from the resin injection port 15 to the cavity K is provided between the center post 30 and the mold surface of the recess 14 of the mold member 11. Is formed. Corresponding to the outer peripheral edge of the upper surface of the center post 30, the ridge 14 a is formed in an annular shape along the outer periphery of the center post 30 on the mold surface of the recess 14. Between the outer peripheral end of the upper surface of the center post 30 and the ridges 14a is a minimum portion 33a where the gap portion 33 is the narrowest.

  Therefore, when the resin Z is injected into the cavity K from the resin injection port 15, the resin Z flows through the gap 33 in all directions around the resin injection port 15 and is supplied to the cavity K. At this time, since the gap portion 33 is narrowest at the minimum portion 33a at the outer peripheral end of the upper surface of the center post 30, the inflow of resin into the cavity K is moderately regulated by the minimum portion 33a. The resin also enters the drop portion 30a of the pin hole 25d of the spool eject pin 27. Thereafter, in the process in which the resin flowing into the cavity K is solidified, the resin Z injected from the resin injection port 15 into the gap 33 is also solidified as an unnecessary resin, and the spool F is formed. In the spool F, the thinnest portion Fa is formed at the minimum portion 33 of the gap portion 33. Further, the resin that has entered the drop portion 30 a of the pin hole 25 d is solidified, whereby the spool F is locked to the upper surface of the center post 30. Further, the resin Z solidified in the resin inlet 15 bites into the lock portion 31b of the spool lock pin 31 and is fastened.

  Next, a control means related to injection molding is shown in a block diagram in FIG. A control device 41 for controlling the injection molding machine is incorporated in the main body of the injection molding machine. An in-mold cavity pressure gauge 42 for detecting the pressure in the cavity K in the mold is connected to the control device 41. Further, the upper mold moving cylinder 43 is connected to the control device 41. Further, an abnormality alarm lamp 44 for warning of molding abnormality is connected to the control device 41.

Next, a resin molding method performed using the above-described resin molding apparatus 1 will be described. FIG. 5 is a flowchart showing the control procedure. In order to resin-seal the stator 2 using the resin molding apparatus 1, the stator 2 is inserted into the recess 29 of the lower mold 4 in the mold open state in which the upper mold 3 is moved upward.
Thereafter, as shown in FIG. 1, the upper die 3 is lowered by the upper die moving cylinder (S1 in FIG. 5) to close the upper die 3 and the lower die 4, and between the upper die 3 and the lower die 4 A cavity K is formed in the cavity K, and the stator 2 is accommodated in the cavity K in a sealed state. That is, the stator core 8 made of a laminated plate material is used as a wall for forming the cavity K.

  Thereafter, the molten resin Z is supplied to the resin passage 6 of the upper mold 3 at a high pressure (S2). As a result, the resin Z is injected into the cavity K through the resin injection port 15 and the gap 33, and the resin is supplied to the winding 9 accommodated in the cavity K. In this embodiment, a thermosetting resin is used as the resin Z. The molten resin Z is heated to a temperature of 40 to 50 ° C., and the mold members 11 and 24 are heated to a temperature of 150 to 160 ° C. At this time, the resin Z supplied from the resin injection port 15 flows through the gap 33 between the upper surface of the center post 30 and the mold member 11 in all directions around the resin injection port 15. Is injected into the cavity K containing the. At this time, since the gap portion 33 is narrowest at the narrowest portion 33a, the inflow of resin into the cavity K is moderately regulated by the narrowest portion 33a. As a result, the resin can be spread evenly over all the windings 9 of the stator 2 and sealed.

Here, molding abnormality detection, which is a main part of the present invention, will be described. After the resin Z melted into the resin passage 6 of the upper mold 3 is started to be fed at a high pressure (S2), the pressure in the molding cavity is measured even if a predetermined time has passed (S3; YES). If the pressure measured by the meter 42 does not exceed the predetermined value (S4; NO), an abnormality is detected (S5).
If the thickness of the stator core 8 made of a laminated plate material is within the reference value, the gap distance of the minimum portion 33a of the upper and lower molds is designed to be 0.5 mm to 0.8 mm. On the other hand, when the gap 33a in the minimum portion is 0.2 mm or less, the flow of the resin deteriorates, and the resin pressure in the molding cavity does not rise to a predetermined value within a predetermined time. Since the resin pressure in the molding cavity is measured by the pressure gauge 42 in the molding cavity, if the pressure measured by the pressure gauge does not reach a predetermined value even after a predetermined time has passed, an abnormality is detected (S5). The abnormality warning lamp 44 is turned on to notify the abnormality to the control device of the injection molding machine (S6).
According to this method, since an abnormality can be detected without bringing the minimum parts of the upper and lower molds into contact with each other, damage to expensive molds can be reduced.

Since the thickness of the stator core 8 made of a laminated plate material is normally inspected in advance, it is unlikely that the stator core 8 will be further reduced. However, it contacts the ridge 14a. That is, as shown in FIG. 3, the distance of the minimum portion 33a of the gap 33 is zero. As a result, the resin Z is blocked at the contact portion between the outer peripheral edge of the upper surface of the center post 30 and the ridge 14a, and does not flow into the cavity K.
Also in this case, the resin pressure in the molding cavity does not rise to a predetermined value within a predetermined time. Since the resin pressure in the molding cavity is measured by the pressure gauge 42 in the molding cavity, if the pressure measured by the pressure gauge does not reach a predetermined value even after a predetermined time has passed, an abnormality is detected (S5). The abnormality warning lamp 44 is turned on to notify the abnormality to the control device of the injection molding machine (S6).

According to the common sense of injection molding engineers so far, the mold is expensive, so the engineer tries to avoid contact with the mold thoroughly. Therefore, a stopper for setting the lowering position limit of the upper mold 3 is provided outside the mold so that the upper mold 3 does not contact the lower mold 4 even when the thickness of the stator core 8 is small.
However, when the applicant forms such a structure, a gap is formed between the upper mold 3 and the stator core 8, and when a thin resin skin is formed in the gap, a bolt is fastened to the thin skin position. I noticed that it could cause the bolts to loosen.
In order to avoid this, the object is to obtain certainty of product quality even at the expense of expensive molds. In that case, the minimum portion 33a is formed on the injection flow path between the upper die 3 and the lower die 4 of the mold, and the minimum portion 33a abuts to block the flow of the resin, so that the thickness of the stator core 8 is increased. In the unlikely event that it is small, an abnormality is detected by the inflow speed of the resin.

  In this embodiment, the molding failure is detected by the pressure increase in the cavity K. However, as another abnormality detection method, the injection of the resin Z stops in the middle when the minimum part comes into contact, and therefore, for a predetermined time. It can be determined that there is an abnormality even if the resin injection stops before the passage. An abnormality can also be detected when the resin injection is not completed when a predetermined time has elapsed and when a predetermined amount of resin is not injected within a predetermined time after the resin injection is started.

On the other hand, when the pressure in the molding cavity rises to a predetermined value or more (S4; YES), it is determined to be normal, the molding is completed (S7), and the upper mold is raised by the upper mold moving cylinder (S8).
FIG. 6 shows an enlarged cross-sectional view near the gap 33. In this mold open state, an unnecessary disk-like spool F corresponding to the upper surface of the center post 30 remains integrally with the stator 2 at the upper center of the resin-sealed stator 2. The spool F includes a conical protrusion F1 formed by the resin injection port 15 at the center thereof. In the protrusion F1, the resin bites into the lock portion 31b and is fastened. Further, on the lower surface of the spool F, a part of the resin Z is engaged with the drop portion 30a of the pin hole 25d. Therefore, when the upper die 3 is opened, the spool F and the projection F1 are locked to the lock post 31b and the drop-in portion 30a and are fastened to the center post 30. For this reason, when the upper die 3 is opened, the spool F can be easily separated from the die member 11 of the upper die 3.

Thereafter, the resin-sealed stator 2 is separated from the lower mold 4, and in order to separate the spool F from the center post 30, the projecting pins 28 are gradually projected upward, and the two eject plates 6, 7 are attached via the legs 7 a. Move it upward gradually. Thereby, the stator eject pin 26 and the spool eject pins 27 and 27A are sequentially moved upward simultaneously.
That is, while the projecting pin 28 is ejected for the entire stroke, until the ejector pin 28 is ejected by about one third, only the stator eject pin 26 is moved upward by moving the two eject plates 6 and 7 upward. Only the sealed stator 2 is pushed out from the recess 29 of the mold member 24. At this time, since the spool eject pins 27 and 27 </ b> A remain stopped, the unnecessary spool F remains on the upper surface of the center post 30.
At this time, since the stator 2 is pushed out of the recess 29 and moves relative to the spool F, the spool F is easily broken at the thinnest portion Fa. For this reason, it is possible to reliably separate the spool F from the stator 2 while keeping the circular shape without breaking the spool F carelessly.

  As described above, according to the stator core molding method of this embodiment, the stator core 8 made of a laminated plate material is sandwiched between the upper and lower molds 3 and 4 to form the molding cavity K, and the resin is injection molded into the molding cavity K. In the stator core molding method, the minimum part 33a of the distance between the upper and lower molds is provided in the gap part 33 between the upper and lower molds forming the resin Z injection gap part passage to the molding cavity K, and the minimum part 33a is injected with the resin reaching the molding cavity K. When the thickness of the stator core 8 is below the reference, the upper and lower molds 3 and 4 abut at the minimum portion 33a when the thickness of the stator core 8 is below the reference. Since the upper and lower molds 3 and 4 come into contact with each other at the minimum portion 33a when being molded, the flow of the resin Z is blocked, so that molding defects due to insufficient resin are caused. Flip, even if the resin thin skin is generated in the stator core 8, it is possible to eliminate the product itself as a defective product. Since the minimum portion 33a extends over the entire circumference of the gap 33 reaching the molding cavity K, the flow of the resin Z can be completely blocked.

In addition, when the injection of resin Z is not completed, an abnormality is detected, so the injection molding machine can detect an abnormality without checking for molding defects. can do. According to this method, since an abnormality can be detected without bringing the minimum parts of the upper and lower molds into contact with each other, damage to expensive molds can be reduced.
Further, since the minimum portion 33a is formed immediately before the molding cavity K, the minimum portion 33a is located at the boundary between the winding mold portion and the unnecessary portion to be removed from the product. Removal is easy. That is, when the mold is opened and the product is taken out, the minimum portion 33a can be easily broken, so that the spool F can be easily removed.

In addition, this invention is not limited to the said embodiment, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.
For example, in the present embodiment, an abnormality is detected when the pressure measured by the pressure gauge does not reach a predetermined value even after a predetermined time has elapsed. Therefore, it may be determined that there is an abnormality when the resin injection is stopped before the predetermined time has elapsed. Anomalies may also be detected when resin injection has not ended when a predetermined time has elapsed and when a predetermined amount of resin has not been injected within a predetermined time since the start of resin injection.

It is sectional drawing which shows the main structures (mold closing state) of the resin molding apparatus. It is sectional drawing which shows the part of the upper mold member and center post in a mold closed state. It is sectional drawing which shows the state which the upper mold member contacted the center post at the time of resin injection | pouring. It is a block diagram which shows the structure of shaping | molding abnormality detection. It is a flowchart of molding abnormality detection. 3 is an enlarged cross-sectional view in the vicinity of a gap 33. FIG. It is sectional drawing which shows the metal mold | die structure of the conventional resin molding apparatus. It is sectional drawing which shows the stopper of the conventional metal mold | die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin molding apparatus 2 Stator 3 Upper mold | type 4 Lower mold | type 8 Stator core 9 Winding 15 Resin inlet 30 Center post (central convex part)
33 Gap 33a Narrowest Z Resin F Spool (unnecessary resin)
K cavity

Claims (3)

In a stator core molding method in which a stator core made of a laminated plate material is sandwiched between upper and lower molds to form a molding cavity, and a resin is injected into the molding cavity to perform injection molding.
Providing a minimum portion of the distance between the upper and lower molds in the gap between the upper and lower molds forming the resin injection passage to the molding cavity;
Extending the minimum part over the entire circumference of the resin injection passage leading to the molding cavity;
When the thickness of the stator core is below a reference, the upper and lower molds are in contact with each other at the minimum portion. In the stator core molding method according to claim 1,
An abnormality detection is performed when the resin injection is not completed. In the stator core molding method according to claim 1 or 2,
A stator core molding method, wherein the minimum portion is formed immediately before the molding cavity.

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