Powder resin coating method and powder resin coating device

Abstract

To provide a powder resin coating method and a powder resin coating device that can form a coating film of a given film thickness on a bridge portion of a coil end portion without making the coating film over the entire coil end portion of a stator too thick.SOLUTION: In a powder resin coating method for applying a coating of powder resin 40 onto a coil end portion 103 of a stator 100, the stator having, in the coil end portion 103 protruding from a stator core 101, a welding portion 104b of coils and a bridge portion 105 arranged at a position farther from the stator core 101 than the welding portion 104b and connecting a plurality of welding portions 104b, the method includes, in addition to a first immersion step for immersing the coil end portion 103 in a heated state into the powder resin 40 to weld the powder resin 40 to the welding portion 104b and the bridge portion 105, at least one second immersion step for immersing only the bridge portion 105 into the powder resin 40 to weld the powder resin 40 to the bridge portion 105.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a powder coating method and a powder coating apparatus. [Background technology]

[0002] Conventionally, a powder resin coating method is known in which a preheated workpiece is immersed in a powder tank that stores powder resin, the powder resin is melted by the heat of the workpiece, and the molten powder resin is welded to the surface of the workpiece to form a coating film (see, for example, Patent Document 1).

[0003] Such powder resin coating is used when forming a coating film on the welded portions between coils arranged at the coil end portions of a stator used in a rotating electric machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6616382 Summary of the Invention [Problem to be solved by the invention]

[0005] The temperature of the workpiece affects the adhesion of the powder resin to the workpiece surface. Therefore, the temperature of the workpiece during powder resin coating is an important factor in forming a highly accurate coating film of a specified thickness on the workpiece surface. However, the coil end portion of the stator has bridge portions that connect multiple welded portions in addition to the welded portions between the coils, and the temperature differs at each of these portions, which makes the coating thickness easily uneven.

[0006] In particular, the bridge portion has a larger area than the welded portion, and is located farther from the stator core than the welded portion, so that the bridge portion is likely to be at a lower temperature than the welded portion. Therefore, if the entire coil end portion is immersed in powdered resin, the coating film on the bridge portion is likely to be thinner than the coating film on the welded portion, and the bridge portion in particular tends to be formed with a thinner corner thickness. As a result, the bridge portion may not satisfy the lower limit requirement for the coating film thickness.

[0007] The coating can be made thicker by increasing the number of times it is immersed in the powder resin, but increasing the number of immersions makes the coating on the coil end too thick, and the increased inner diameter of the coil end raises the risk of interference with the rotor. It is also possible to increase the immersion time in the powder resin each time to increase the coating thickness, but in low-temperature areas, even if the immersion time is increased, heat transfer to the powder resin becomes saturated, so the powder resin does not melt and an increase in coating thickness cannot be expected.

[0008] Therefore, the present invention aims to provide a powder resin coating method and a powder resin coating apparatus that can form a coating film of a predetermined thickness on the bridge portion of the coil end portion without the coating film becoming too thick over the entire coil end portion of the stator. [Means for solving the problem]

[0009] (1) A powder resin coating method for coating a powder resin (e.g., powder resin 40 described later) on a coil end portion (e.g., coil end portion 103 described later) of a stator (e.g., stator core 101 described later), the coil end portion having a welded portion (e.g., welded portion 104b described later) between coils and a bridge portion (e.g., bridge portion 105 described later) that is positioned farther from the stator core than the welded portion and connects the multiple welded portions, the powder resin coating method further includes a first immersion step in which the coil end portion in a heated state is immersed in the powder resin to weld the powder resin to the welded portion and the bridge portion, and a second immersion step in which only the bridge portion is immersed in the powder resin to weld the powder resin to the bridge portion at least once.

[0010] According to (1) above, the coating film of a predetermined thickness can be formed stably and with high precision on the bridge portions of the coil ends, where the coating film is likely to become thin, without the coating film becoming too thick over the entire coil end portion of the stator.

[0011] (2) In the powder resin coating method described in (1) above, the second immersion step may be carried out after the first immersion step.

[0012] According to (2) above, even if the second immersion process is carried out after the first immersion process, the coating film on the entire coil end portion of the stator does not become too thick, and a coating film of a predetermined thickness can be stably and precisely formed on the bridge portion of the coil end portion, where the coating film is likely to become thin.

[0013] (3) In the powder resin coating method described in (2) above, the second dipping step may be a final step in which the powder resin is applied to the coil end portion.

[0014] According to (3) above, even if the second immersion process is performed as the final process, the coating film on the entire coil end portion of the stator does not become too thick, and a coating film of a predetermined thickness can be stably and precisely formed on the bridge portion of the coil end portion, where the coating film is likely to become thin.

[0015] (4) A powder resin coating device (for example, powder resin 40 described later) that coats a powder resin (for example, powder resin 40 described later) on a coil end portion (for example, coil end portion 103 described later) of a stator (for example, stator 100 described later) having a welded portion (for example, welded portion 104b described later) between coils and a bridge portion (for example, bridge portion 105 described later) that is disposed at a position farther from the stator core than the welded portion and connects the plurality of welded portions, the powder resin coating device (for example, powder resin 40 described later) includes a powder tank (for example, powder tank 4 described later) that stores the powder resin. 3), a conveying device (e.g., robot 2 described below) that holds the stator and immerses the coil end portion in the powder tank, and a control device (e.g., control device 3 described below) that controls the operation of the conveying device, wherein the control device controls the operation of the conveying device so as to perform at least one second immersion operation of immersing only the bridge portion in the powder tank to weld the powder resin to the bridge portion in addition to a first immersion operation of immersing the heated coil end portion in the powder tank to weld the powder resin to the weld portion and the bridge portion.

[0016] According to the above (4), it is possible to provide a powder resin coating device that can stably and precisely form a coating film of a predetermined thickness on the bridge portion of the coil end portion, where the coating film is likely to become thin, without the coating film becoming too thick over the entire coil end portion of the stator.

[0017] (5) In the powder resin coating apparatus described in (4) above, the control device may control the operation of the transport device so that the second immersion operation is performed after the first immersion operation.

[0018] According to (5) above, even if the second immersion process is carried out after the first immersion process, the coating film on the entire coil end portion of the stator does not become too thick, and a coating film of a predetermined thickness can be stably and precisely formed on the bridge portion of the coil end portion, where the coating film is likely to become thin.

[0019] (6) In the powder resin coating apparatus described in (5) above, the control device may control the operation of the conveying device so that the second immersion operation is performed at the end of the operation of coating the powder resin on the coil end portion.

[0020] According to the above (6), even if the second immersion process is performed last, the coating film on the entire coil end portion of the stator does not become too thick, and a coating film of a predetermined thickness can be stably and precisely formed on the bridge portion of the coil end portion, where the coating film is likely to become thin. Effect of the Invention

[0021] According to the present invention, a powder resin coating method and a powder resin coating apparatus can be provided that can form a coating film of a predetermined thickness on the bridge portion of the coil end portion without the coating film becoming too thick over the entire coil end portion of the stator. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a powder resin coating device. [Diagram 2] FIG. 2 is a functional block diagram of a control device of the powder resin coating apparatus. [Diagram 3] FIG. 4 is a perspective view of the stator showing the coil end portion before powder resin coating. [Figure 4] 4A and 4B are diagrams illustrating a configuration of a coil end portion of a stator. [Diagram 5] 11A and 11B are diagrams showing a process of immersing a stator in a powder bath. [Figure 6] FIG. 2 is a diagram showing the first immersion step of powder resin coating. [Figure 7] FIG. 13 shows the second immersion step of powder resin coating. [Figure 8] FIG. 1 is a diagram showing the immersion height in the first immersion step and the second immersion step of powder resin coating. [Figure 9] FIG. 4 is a perspective view of the stator showing the coil end portion after powder resin coating. [Figure 10] 13 is a graph showing the relationship between the number of times of immersion in a powder tank and the thickness of the coating film on the bridge portion. [Figure 11] 13 is a graph showing the relationship between the number of times of immersion in a powder tank and the minimum film thickness of the coating film on the bridge portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 shows a schematic configuration of a powder resin coating apparatus 1. The powder resin coating apparatus 1 includes a robot 2, a control device 3, and a powder fluidization tank 4.

[0024] The robot 2 is an example of a conveying device that conveys a stator 100, which is a workpiece. The stator 100 is, for example, a stator for an in-vehicle rotating electric machine. The robot 2 has an arm unit 21 at its tip that can move to any position and direction. A hand unit 22 that holds the stator 100 is provided at the tip of the arm unit 21.

[0025] The control device 3 controls various operations of the arm unit 21 and the hand unit 22 of the robot 2. As shown in Fig. 2, the control device 3 includes an operation control unit 31 and a memory 32. The operation control unit 31 is configured with a CPU (Central Processing Unit) and generates an operation command for the robot 2 to perform powder resin coating on the coil end portion of the stator 100. The memory 32 stores a program for executing the operation of the robot 2 required for generating the operation command in the operation control unit 31, various parameters, etc.

[0026] The operation control unit 31 transmits the generated operation command to the robot 2. The robot 2 operates the arm unit 21 and the hand unit 22 based on the operation command received from the operation control unit 31, and transports and moves the stator 100 held by the hand unit 22. The operation command generated by the operation control unit 31 includes an operation command related to the immersion height and the number of immersions for immersing the coil end portion of the stator 100 in the powder resin 40 in the powder tank 43 described later.

[0027] The powder fluidized tank 4 is installed within the movable area of ​​the arm unit 21 of the robot 2, and has a powder tank 43 supported on a support leg 41. The powder tank 43 has two partition plates 43a therein, and the powder resin 40 is stored in the space above the partition plates 43a.

[0028] Air is supplied to the powder tank 43 from an air inlet 43b below the partition plate 43a. A vibration motor 44 is disposed below the powder tank 43. The powder fluidization tank 4 fluidizes and liquefies the powder resin 40 in the powder tank 43 by air flowing in from the air inlet 43b and vibration generated by driving the vibration motor 44. The powder resin flowing out of the powder tank 43 is collected in a hopper 42 below the powder tank 43 and is collected by a dust collector (not shown) via a discharge port 42a.

[0029] Next, the configuration of the stator 100 to be powder resin coated will be described with reference to Figures 3 and 4. The stator 100 has a stator core 101 formed by laminating multiple thin electromagnetic steel sheets having a substantially circular shape with an opening in the center, and coil end portions 103 protruding from multiple slots 102 provided in the stator core 101.

[0030] 3 and 4 show only the coil end portion 103 protruding from one end face 101a in the central axis direction of the stator core 101, but the coil end portion 106 also protrudes from the other end face 101b of the stator core 101 (see FIGS. 5 to 7). Of the coil end portions 103, 106, only the coil end portion 103 is coated with the powder resin.

[0031] The coil end portion 103 is an assembly of multiple coils 104 that protrude from each of the multiple slots 102 and are bent in the circumferential direction, and protrudes in an annular shape in the central axis direction (the up and down direction in Figs. 3 and 4) from the stator core 101. The coils 104 use a conductor made of a flat wire with a rectangular cross section.

[0032] As shown in Fig. 4, the outer surface of the coil 104 is covered with a resin coating 104a. However, the tip of each coil 104 is not covered with the resin coating 104a, and the conductor is exposed. Coils 104 of the same phase among the multiple coils 104 protruding from the slot 102 are electrically connected by welding the tips where the conductor is exposed. As a result, a welded portion 104b where the coils 104 are joined to each other is formed at the tip of each coil 104. The positions of the welded portions 104b are aligned so as to be located at approximately the same height from the end face 101a of the stator core 101.

[0033] Some of the coils 104 protrude higher than the position of the welded portion 104b, which is aligned at approximately the same height from the stator core 101, and are connected to the bridge portion 105. The bridge portion 105 is formed in a strip shape with a rectangular cross section by the same conductor as that used for the coils 104. The bridge portion 105 electrically connects the tips of the coils 104 of the same phase, which are located apart from each other in the circumferential direction of the stator core 101, among the coils 104 protruding higher than the position of the welded portion 104b, at a position farther from the end face 101a of the stator core 101 than the welded portion 104b. The length direction of the bridge portion 105 extends along the circumferential direction of the stator core 101. The width direction of the bridge portion 105 is arranged along the central axis direction of the stator core 101 (the vertical direction in Figs. 3 and 4).

[0034] The bridge portion 105 does not have a resin coating. Therefore, as shown in Fig. 4, in the coil end portion 103 protruding from the end face 101a of the stator core 101, the region from the end face 101a to just before the welded portion 104b is a resin-coated region covered with the resin coating 104a, and the region of the welded portion 104b and the bridge portion 105 is a conductor exposed region without a resin coating. The powder resin coating is applied to at least the conductor exposed region of the resin-coated region and the conductor exposed region of the coil end portion 103.

[0035] Next, a method for applying powder resin coating to the coil end portion 103 of the stator 100 by the powder resin coating apparatus 1 will be described with reference to Fig. 5 to Fig. 11. Note that the robot 2 that holds and transports the stator 100 is not shown in Fig. 5, Fig. 6, and Fig. 8.

[0036] 5, in the powder resin coating, the stator 100, which has been heated to a predetermined temperature in advance, is held by the hand unit 22 of the robot 2 in a position in which the coil end portion 103, which is the target of the powder resin coating, faces downward, and is immersed in the powder resin 40 in the powder tank 43 by a conveying operation of the arm unit 21, which operates based on an operation command transmitted from the control device 3. In this embodiment, the conveying operation of the arm unit 21 of the robot 2 includes a first immersion operation for performing a first immersion step on the stator 100, and a second immersion operation for performing a second immersion step.

[0037] The first dipping step is a step of dipping the coil end portion 103 of the stator 100 into the powder resin 40 in the powder tank 43 by the conveying operation of the arm portion 21 of the robot 2, as shown in Fig. 6. At this time, the stator 100 moves to the lower end position of the dipping operation, and at least the entire conductor exposed region of the coil end portion 103 is dipped below the powder surface of the powder resin 40 in the powder tank 43. The powder resin 40 melts due to the heat of the coil end portion 103 and adheres to the coil end portion 103. As a result, the powder resin 40 is welded to at least the conductor exposed region including the welded portion 104b and the bridge portion 105 of the coil end portion 103.

[0038] As shown in FIG. 7, the second immersion step is a step in which only the bridge portion 105 in the coil end portion 103 of the stator 100 is immersed in the powder resin 40 in the powder tank 43 by the conveying operation of the arm portion 21 of the robot 2. At this time, the stator 100 does not move to the lower end position of the immersion operation. Therefore, the bridge portion 105 in the coil end portion 103 is immersed below the powder surface of the powder resin 40 in the powder tank 43, but the welding portion 104b, which is closer to the stator core 101 than the bridge portion 105, is positioned above the powder surface of the powder resin 40 and is not immersed in the powder resin 40. The powder resin 40 melts due to the heat of the bridge portion 105 and adheres to the bridge portion 105. As a result, the powder resin 40 is welded only to the bridge portion 105 in the conductor exposed region.

[0039] 8 shows a specific immersion operation performed by the powder resin coating apparatus 1 of this embodiment. When performing powder resin coating in which the coil end portion 103 is immersed in the powder resin 40 in the powder tank 43, the powder resin coating apparatus 1 controls the transport operation of the robot 2 by the control device 3 so that a second immersion operation for performing a second immersion step is added at least once in addition to a first immersion operation for performing a first immersion step. Here, the immersion operation of the stator 100 in the powder resin 40 in the powder tank 43 is divided into three times, with the first immersion operation being performed twice and the second immersion operation being performed once.

[0040] First, the powder resin coating apparatus 1 transmits an operation command to the robot 2 by the control device 3 to perform the first dipping operation on the stator 100 twice at a predetermined interval as a normal dipping operation. In detail, the powder resin coating apparatus 1 moves the stator 100 to the lower end position by the first dipping operation to dipped the coil end portion 103 in the powder resin 40 for a predetermined time, and then returns the stator 100 to the upper end position where dipping is not performed. When a predetermined time has elapsed after the first dipping operation is completed, the powder resin coating apparatus 1 again performs the same first dipping operation for a predetermined time. As a result, the powder resin 40 is welded to at least the entire conductor exposed region of the coil end portion 103. By performing the first dipping operation twice, a coating film having a necessary and sufficient predetermined thickness is formed on the welded portion 104b.

[0041] Of the coil end portions 103, the bridge portion 105 has a lower temperature than the welded portion 104b. Therefore, it is difficult to form a sufficient coating film on the bridge portion 105 by performing only the first dipping operation twice. Therefore, the powder resin coating apparatus 1 adds one second dipping operation at the end.

[0042] In detail, the powder resin coating device 1 executes the second dipping operation after a predetermined time has elapsed since the second first dipping operation is completed, and dipped only the bridge portion 105 of the coil end portion 103 in the powder resin 40 for a predetermined time. The powder resin 40 adhering to the bridge portion 105 immediately before the second dipping operation is in a semi-molten state when the second first dipping operation is completed and the powder resin 40 is removed from the powder surface. In this state, the intermolecular force of the powder resin 40 is increased, so that the powder resin 40 easily adheres to the bridge portion 105 even if the bridge portion 105 is at a low temperature. Therefore, the thickness of the coating film on the bridge portion 105 increases to a predetermined thickness that is necessary and sufficient.

[0043] 9, the entire exposed conductor region of the coil end portion 103, including the welded portion 104b and the bridge portion 105, is covered with the coating film 107. The second dipping operation is for dipping only the bridge portion 105, and the welded portion 104b, on which a coating film of a predetermined and sufficient thickness has already been formed, is not dipped into the powder resin 40, so that the coating film of the coil end portion 103 does not become thicker than necessary. Therefore, the coating film 107 with a stable and highly accurate thickness is formed on the entire exposed conductor region of the coil end portion 103.

[0044] 10 shows the thickness of the coating film at any location (B1, B2, D) of bridge portion 105 at the end of two first dipping operations and at the end of the last added second dipping operation. It was confirmed that the thickness of the coating film on bridge portion 105 increases by adding the second dipping operation in which only bridge portion 105 is dipped in powder resin 40.

[0045] 11 shows the minimum thickness of the coating film at any location (B1, B2, D) of bridge portion 105 at the end of two first dipping operations and at the end of the last added second dipping operation. It was confirmed that by adding the second dipping operation in which only bridge portion 105 is dipped in powder resin 40, the minimum thickness of the coating film on bridge portion 105 increases and a predetermined thickness is formed even at the corners of bridge portion 105.

[0046] In this way, by adding a second dipping operation of dipping only the bridge portion 105 in powder resin 40 in addition to the first dipping operation of dipping the entire coil end portion 103 and dipping the welded portion 104b and the bridge portion 105 in powder resin 40, it is possible to homogenize the coating film of the entire coil end portion 103 to a predetermined film thickness. Since the first dipping operation of dipping the welded portion 104b, which affects the inner diameter of the coil end portion 103, in powder resin 40 only needs to be performed a minimum number of times, there is no risk of the inner diameter of the coil end portion 103 increasing.

[0047] In the above embodiment, the second immersion operation for performing the second immersion step is performed only once during powder resin coating, but the second immersion operation is not limited to only once, and may be added at least once to the first immersion operation for performing the first immersion step. Therefore, for example, the second immersion operation for performing the second immersion step may be performed at the beginning of powder resin coating. Also, the second immersion operation may be performed after the initial first immersion operation is performed, and then the first immersion operation may be performed again.

[0048] In the above embodiment, the second immersion operation to perform the second immersion process is performed as the final process after the first immersion operation is completed, but the second immersion operation may be performed at any arbitrary timing during powder resin coating. [Explanation of symbols]

[0049] 1 Powder resin coating equipment 2 Robot (transport device) 3. Control device 40 Powdered resin 43 Powder tank 100 Stator 101 Stator core 103 Coil end 104b Welding 105 Bridge section

Claims

1. A powder resin coating method for coating a powder resin on a coil end portion of a stator having a coil end protruding from a stator core, the coil end portion having a welded portion between coils and a bridge portion disposed farther from the stator core than the welded portion and connecting the plurality of welded portions, A powder resin coating method, in which, in addition to a first immersion process in which the heated coil end portion is immersed in the powder resin to weld the powder resin to the weld portion and the bridge portion, a second immersion process in which only the bridge portion is immersed in the powder resin to weld the powder resin to the bridge portion is added at least once.

2. The powder resin coating method according to claim 1 , wherein the second dipping step is carried out after the first dipping step.

3. 3. The powder resin coating method according to claim 2, wherein the second dipping step is a final step for coating the powder resin on the coil end portion.

4. A powder resin coating device that coats powder resin on a coil end portion of a stator having a coil end protruding from a stator core, the coil end portion having a welded portion between coils and a bridge portion that is disposed farther from the stator core than the welded portion and connects the plurality of welded portions, A powder tank for storing the powder resin; a conveying device that holds the stator and immerses the coil end portion in the powder bath; A control device for controlling the operation of the conveying device, The control device controls the operation of the conveying device so as to add, at least once, a second immersion operation in which only the bridge portion is immersed in the powder tank to weld the powder resin to the bridge portion, in addition to a first immersion operation in which the heated coil end portion is immersed in the powder tank to weld the powder resin to the weld portion and the bridge portion.This is a powder resin coating device.

5. 5. The powder resin coating apparatus according to claim 4, wherein the control device controls the operation of the transport device so that the second dipping operation is performed after the first dipping operation.

6. 6. The powder resin coating apparatus according to claim 5, wherein the control device controls the operation of the transport device so that the second dipping operation is performed at the end of an operation of coating the powder resin on the coil end portion.

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