Inspection device and inspection method

First to eighth laser measurement sections (30a) to (30h) of a laser measurement unit (30) measures a height of a surface of powder resins (15) in a coil insertion range CA for every angular degree in a circumferential direction of a stator core (2). A control unit (18) computes the number of points where the height of the surface is lower than a predetermined height among measurement results at multiple points measured by the first to eighth laser measurement sections (30a) to (30h), where the number of points is defined as an index value indicative of a dispersion of the measurement results. When it has been determined that the index value exceeds a first predetermined value, a notification is issued by outputting from a speaker (32) a sound indicative of the fact that the index value that has been computed exceeds the first predetermined value.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an inspection device and an inspection method for inspecting a height of a surface of powder resins loaded in a fluidizing tank.

Description of the Related Art

A known powder coating device performs powder coating on workpiece such as an electrical conductor used in a rotating electric machine. The powder coating device disclosed in Japanese Patent No. 5742743 comprises a powder fluidizing tank loaded with powder resins, a porous plate provided below the powder fluidizing tank, and an air feeding unit that feeds air to the powder fluidizing tank via the porous plate. The powder resins are made to flow by the air, the workpiece is inserted into the fluidized powder resins, and thereby power coating is performed on the electrical conductor.

When there is unevenness in the heights of the surface of the powder resins loaded in the powder fluidizing tank, unevenness in the powder coating on the workpiece may occur. The powder coating device disclosed in Japanese Patent No. 5742743 suppresses the occurrence of the unevenness in the powder coating on the workpiece by adjusting the angle of insertion of the workpiece into the powder fluidizing tank in accordance with the inclination of the surface of the powder resins.

However, when the angle of insertion of the workpiece into the powder fluidizing tank is adjusted in the powder coating device disclosed in Japanese Patent No. 5742743, the workpiece sometimes hits the side surface of the powder fluidizing tank. When the workpiece hit the side surface of the powder fluidizing tank, the powder resins may oscillate due to the impact at the time the former hit the latter, causing unevenness in the heights of the surface of the powder resins, which leads to unevenness in the powder coating on the workpiece.

The present invention has been made in view of the above-described aspect and an object of the present invention is to provide an inspection device and an inspection method that can urge suppression of occurrence of uneven powder coating on a workpiece.

SUMMARY OF THE INVENTION

An inspection device of the present invention is an inspection device inspecting a height of a surface of powder resins in a powder coating device, the powder coating device being adapted to feed air toward a fluidizing tank via a porous body provided below the fluidizing tank, wherein the fluidizing tank has closed-end sides and an open-end bottom, fluidize the powder resins loaded in the fluidizing tank, and subject a workpiece inserted into the fluidizing tank to powder coating, the inspection device including: a surface height measurement unit configured to measure the height of the surface of the powder resins loaded in the fluidizing tank at multiple positions; an index value computation unit configured to compute an index value indicative of a dispersion of measurement results measured by the surface height measurement unit at the multiple positions; and a notification unit configured to provide a predetermined notification indicating that the index value computed by the index value computation unit exceeds a first predetermined value in response to the index value exceeding the first predetermined value.

When clogging of the porous body occurs, fluidity of the powder resins in the fluidizing tank deteriorates and dispersion is created in the heights of the surface of the powder resins. When the dispersion of the heights of the surface of the powder resins becomes large, the uneven coating on the workpiece will also increase.

According to the inspection device of the present invention, when the dispersion of the heights of the surface of the powder resins exceeds the first predetermined value due to the clogging of the porous plate, this fact is notified. By specifying the first predetermined value as a value, the dispersion above which causes larger unevenness of coating on the workpiece, it is made possible to notify the fact that the uneven coating on the workpiece will increase and urge countermeasures to prevent the consequence.

It is preferable that the surface height measurement unit is configured to measure the height of the surface of the powder resins loaded in the fluidizing tank at a portion of the fluidizing tank where the workpiece is inserted.

According to this feature, it is possible to measure only the necessary portion, reduce waste, and improve efficiency.

It is preferable that the surface height measurement unit is arranged above the portion where the workpiece is inserted.

According to this feature, it is made possible to measure only the necessary part using a simple configuration.

It is preferable that the notification unit is configured to provide, as the predetermined notification, a notification urging replacement of the porous body.

According to this feature, it is possible to notify the time of replacement in accordance with the execution status of the first notification. For example, the index value may exceed the first predetermined value due to an external force or the like, making it difficult to determine whether or not the porous body should be immediately replaced in response to the index value having exceeded the first predetermined value. In view of this, the second notification should be performed when, as the execution status of the first notification, the first notification has been issued for a predetermined number of times (multiple times) within a predetermined period of time, which makes it possible to recognize the time of replacement at which the replacement should in fact be carried out.

It is preferable that a signal output unit is provided which is configured to output an insertion stop signal for stopping insertion of the workpiece into the fluidizing tank, the insertion stop signal being output in response to the index value computed by the index value computation unit exceeding a second predetermined value larger than the first predetermined value.

According to this feature, it is made possible to effectively and reliably prevent occurrence of uneven powder coating on the workpiece due to the clogging of the porous plate.

An inspection method according to the present invention is an inspection method of inspecting a height of a surface of powder resins in a powder coating device, the powder coating device being adapted to feed air toward a fluidizing tank via a porous body provided below the fluidizing tank, wherein the fluidizing tank has closed-end sides and an open-end bottom, fluidize the powder resins loaded in the fluidizing tank, and subject the workpiece inserted into the fluidizing tank to powder coating, the inspection method including: a surface height measurement step of measuring the height of the surface of the powder resins loaded in the fluidizing tank at multiple positions; an index value computation step of computing an index value indicative of a dispersion of measurement results at the multiple positions in the surface height measurement step; and a notification step of notifying a fact that the index value computed in the index value computation step has exceeded a predetermined value in response to the index value having exceeded the predetermined value.

According to the inspection method of this invention, it is made possible to provide a notification to the effect that the dispersion occurs in the heights of the surface of the powder resins due to the clogging of the porous plate leading to the problematic increase in the unevenness in the application on the workpiece and thereby urge countermeasures to prevent this problematic event.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, an example of the structure of a rotary electric machine is described.

As illustrated inFIG. 1, a rotary electric machine which may be an electric motor, an electric generator, etc. comprises a stator1formed in a cylindrical shape and a rotor (not shown) rotatably arranged inside the stator1.

The stator1comprises a stator core2and a coil3. The stator core2has a cylindrical shape and includes a plurality of slots2aextending therethrough in the direction along the rotation axis, where the slots2aare provided at intervals in the circumferential direction. Each slot2ais formed such that a cross-sectional shape in the radial direction of the stator core2radially extends radially outward from the center of the stator core2. Each slot2ais in communication with the inner circumferential surface of the stator core2via a slit2bformed in the stator core2. It should be noted that the slit2bmay be omitted.

The coil3is configured by inserting a coil segment4illustrated inFIG. 3into the slot2afrom one side thereof and bending a projecting portion4dprojecting from the other side of the slot2ain the circumferential direction and then welding the projecting portion4d.

The coil segment4is configured by aligning a plurality of conductors (four conductors in this embodiment) having a rectangular cross-section (conductors of rectangular wires) in one row so that their wide surfaces face with each other and bundling them in a U-shape. The coil segment4is constituted by a pair of leg sections4a,4aand a head section4binterconnecting one ends of these two leg section4a,4a(the upper ends in the figure).

It should be noted that the coil segment4may be a bundle of multiple rectangular wires aligned in the width direction and, for example, the coil segment4may also be a bundle of rectangular wires aligned in one row such that their narrow surfaces face with each other.

An S-shaped section4ccurved in an S shape in the direction of alignment of the rectangular wires is formed at the center of the head section4b. Also, the head section4bis inclined from its center (the center of the S-shaped section4c) toward the two leg sections4a,4a. The leg section4aof the coil segment4is inserted into the corresponding slot2afrom one side thereof. The leg section4aof the coil segment4projects from the other side of the slot2a.

The projecting portion4dof the leg section4aprojecting from the other side of the slot2ais bent, as illustrated inFIG. 4A, by a bending device (not shown) in the circumferential direction of the stator1, and the tip sections4eof the corresponding projecting portions4dare joined by welding by a welding device (not shown). In this manner, a stator1is completed which comprises eight layers of (eight) coil segments4are arranged in a stacked state in the radial direction. Here, the first layer, the second layer . . . and the eighth layer are arranged from the outer side to the inner side in the radial direction.

It should be noted that the coil3of this embodiment is a three-phase coil consisting of U-phase, V-phase, and W-phase. The leg sections4aof the coil segment4inserted into the respective slots2aare arranged in the order of U-phase, U-phase, V-phase, V-phase, W-phase, and W-phase. InFIG. 4Bonly one coil (e.g., a U-phase coil) out of the three phases is depicted.

Next, as illustrated inFIGS. 5 and 6, a powder coating device10will be described which performs powder coating on the projecting portion4dof the leg section4aof the coil segment4(workpiece) using a fluidized bed coating technique.

The powder coating device10comprises a powder fluidizing tank16loaded with powder resins15comprising resin having an insulating property (e.g., epoxy resin) and having a particle diameter of, for example, 55 μm (0.055 mm), and an oscillation unit17configured to oscillate the powder fluidizing tank16. The powder fluidizing tank16has a closed-end sides and an open-end bottom. The oscillation unit17has an eccentric vibration motor or the like and is configured to oscillate the central-axis portion of the powder fluidizing tank16and thereby causes the powder fluidizing tank16to oscillate in the lateral direction and the axial direction.

Also, the powder coating device10comprises a control unit18configured to comprehensively control the powder coating device10and a stator moving mechanism19configured to hold and move the stator1. Actuation of the oscillation unit17and the stator moving mechanism19is controlled by the control unit18.

The powder coating device10comprises a first porous plate21and a second porous plate22(porous body) disposed below the powder fluidizing tank16, a porous plate holding unit23configured to hold the first porous plate21and the second porous plate22, and an air feeding unit24. Actuation of the air feeding unit24is controlled by the control unit18.

A plurality of holes with a diameter of for example 0.01 mm are formed in the first porous plate21and a plurality of holes with a diameter larger than the hole diameter of the first porous plate21, for example, 2 mm, are formed in the second porous plate22. It should be noted that the second porous plate22may be omitted as long as at least the first porous plate21is provided. Further, three or more porous plates may be provided.

The porous plate holding unit23comprises a first holding plate23a, a second holding plate23b, and a third holding plate23c. The first holding plate23ais detachably attached to the second holding plate23b. The first porous plate21is held by and between the first holding plate23aand the second holding plate23b.

The third holding plate23cis detachably attached to the second holding plate23b. The second porous plate22is held by and between the third holding plate23cand the second holding plate23b. The porous plates21,22and the holding plates23ato23care each sealed by a ring-shaped rubber.

The air feeding unit24is disposed below the first porous plate21. The air feeding unit24is configured to feed air upward toward the first porous plate21and the second porous plate22.

The powder coating device10comprises a laser measurement unit30(surface height measurement unit) configured to measure the height of the surface of the powder resins15, a rotation mechanism31configured to rotate the laser measurement unit30about a central axis extending in the up-and-down direction of the powder fluidizing tank16, and a speaker32(notification unit). In this embodiment, the inspection device35that inspects the height of the surface of the powder resins15comprises the control unit18, the laser measurement unit30, the rotation mechanism31, and the speaker32.

The laser measurement unit30comprises first to eighth laser measurement sections30ato30hof a laser reflection type (surface height measurement unit) configured to measure the height of the surface of the powder resins15. The first to eighth laser measurement sections30ato30hare provided one after another from the inner circumference so as to measure the height of the surface of the powder resins15at multiple locations (e.g., eight locations). While details will be described later, the projecting portions4dof the eight coil segments4are inserted into the powder fluidizing tank16. The range where the projecting portions4dof the eight coil segments4are inserted defines the coil insertion range CA.

The first to eighth laser measurement sections30ato30hare arranged so as to measure the height of the surface of the powder resins15at each of the eight locations where the projecting portions4dof the eight coil segments4are inserted. Actuation of the first to eighth laser measurement sections30ato30his controlled by the control unit18.

The surface height measurement unit that measures the height of the surface of the powder resins15is not limited to the laser measurement unit30that uses laser and can be modified as appropriate as long as it is capable of measuring the surface height. For example, a measurement unit that measures the surface height on the basis of an image of a surface of the powder resins15may be provided, and another contact-type unit may be provided that measures the surface height by being brought into contact with the surface of the powder resins15.

A case will be described below in which the powder coating is performed on the projecting portions4dof the leg sections4aof the coil segments4by the powder coating device10. In the powder coating, first, the projecting portions4dof the leg sections4aof the coil segments4are heated to a temperature equal to or higher than the melting temperature of the powder resins15by a heating device (not shown).

The control unit18of the powder coating device10actuates the oscillation unit17to oscillate the powder fluidizing tank16. Also, the control unit18actuates the air feeding unit24to feed air from the air feeding unit24to the second porous plate22. The air that has been fed passes through the second porous plate22and the first porous plate21and sent to the powder fluidizing tank16. The powder resins15loaded in the powder fluidizing tank16are made to flow as a result of the oscillation by the oscillation unit17and feeding of the air.

Specifically, since the oscillation unit17oscillates the central-axis portion of the powder fluidizing tank16and oscillates the powder fluidizing tank16in the lateral direction, the outer circumferential portion of the powder fluidizing tank16exhibits a larger oscillation than that of the central portion of the powder fluidizing tank16. As a result, the outer circumferential portion of the powder fluidizing tank16will have a larger bulk density of the powder resins15than that at the central portion of the powder fluidizing tank16.

Accordingly, it is more difficult for the air to pass through the outer circumferential portion of the powder fluidizing tank16than the central portion of the powder fluidizing tank16. In other words, it is easier for the air to pass through the central portion of the powder fluidizing tank16. As a result, the air passing through the central portion of the powder fluidizing tank16becomes an air flow that flows toward the outer circumferential portion of the powder fluidizing tank16, as a result of which the powder resins15loaded in the powder fluidizing tank16is made to flow.

In addition, as illustrated inFIG. 7, the control unit18actuates the stator moving mechanism19to hold the stator1and move the stator1downward, and inserts the projecting portions4dof the leg sections4aof the coil segments4into the powder fluidizing tank16(powder coating step). It should be noted thatFIG. 7illustrates in a simplified manner the projecting portions4dof the coil segments4as an end view along the shape of the projecting portion4d.

The powder resins15flowing in the powder fluidizing tank16are brought into contact with the projecting portions4d. Since the projecting portions4dare heated to the temperature higher than the melting temperature of the powder resins15, the powder resins15in contact with the projecting portions4dare melted and a coating film is formed, and a state is established where powder coating has been performed on the projecting portions4d.

After the control unit18has performed the powder coating for a predetermined period of time, the control unit18stops the actuation of the oscillation unit17. Further, the control unit18actuates the stator moving mechanism19to move the stator1upward and removes the projecting portions4dof the leg sections4aof the coil segments4from the powder fluidizing tank16.

The projecting portions4dof the leg sections4aof the multiple coil segments4removed from the powder fluidizing tank16are subjected to the powder coating and placed in an insulated state.

Further, the control unit18actuates the stator moving mechanism19to move the stator1sideways and evacuate the stator1from the above the powder fluidizing tank16.

The control unit18of the inspection device35, after having evacuated the stator1from the space above the powder fluidizing tank16, actuates the first to eighth laser measurement sections30ato30hof the laser measurement unit30. The first to eighth laser measurement sections30ato30hmeasures the heights of the surface of the powder resins15in the coil insertion range CA. Specifically, the first to eighth laser measurement sections30ato30heach emit a laser beam to irradiate the surface of the powder resins15in the coil insertion range CA with the laser beams, receive the reflected light therefrom, and measure the heights of the surface of the powder resins15on the basis of the received reflected light.

Also, the control unit18actuates the rotation mechanism31to rotate the first to eighth laser measurement sections30ato30hof the laser measurement unit30in the circumferential direction of the powder fluidizing tank16. By virtue of this, the height of the surface of the powder resins15in the coil insertion range CA can be measured for the entire circumference.

In this embodiment, the control unit18actuates the first to eighth laser measurement sections30ato30hsuch that the surface heights at numerous points 250 points) in the circumferential direction of the powder fluidizing tank16for each predetermined angle (e.g., 1°) are measured by the first to eighth laser measurement sections30ato30hof the laser measurement unit30. Further, the control unit18actuates the first to eighth laser measurement sections30ato30hsuch that the measurements are performed for each angular degree up to 360 times in the circumferential direction of the powder fluidizing tank16.

The control unit18computes, as an index value indicative of the dispersion of the measurement results, the number of the points lower than the preset predetermined height among the measurement results at the multiple points (360×250 points and thus a total of 90,000 points in this embodiment) measured for each angular degree in the circumferential direction of the stator core2by the first to eighth laser measurement sections30ato30h. In this embodiment, the control unit18functions as the index value computation unit. The predetermined height can be modified as appropriate. It should be noted that an index value computation unit configured by a CPU or the like calculating the index may be provided separately from the control unit18comprehensively controlling the powder coating device10.

It should be noted that, while the index value needs to be indicative of the dispersion of the measurement results, the index value is not limited to the number of points lower than the predetermined height among the measurement results at the multiple points. For example, the index value may be given as a difference between the maximum value and the minimum value among the measurement results at the multiple points, a deviation of the measurement results, a standard deviation of the measurement results, or the like. Further, the index value may be given as the number of measurement results that are smaller than the maximum value by a predetermined value or more.

The control unit18determines whether or not the computed index value exceeds the preset first predetermined value. A value used to determine that clogging of the first porous plate21occurs when the computed index value exceeds the value is specified as the first predetermined value.

The first predetermined value can be modified as appropriate. For example, if the first predetermined value is made smaller, clogging of the first porous plate21can be more strictly determined. If the first predetermined value is made larger, the determination of the clogging of the first porous plate21becomes less strict.

Even when dispersion occurs in the heights of the surface of the powder resins15(clogging of the first porous plate21occurs), the powder coating device10can perform the powder coating on the projecting portion4dof the multiple coil segments4as long as the dispersion is small.

Meanwhile, if the dispersion of the heights of the surface of the powder resins15is large, then the powder coating device10may not be able to perform the powder coating on the projecting portion4dof the multiple coil segments4(poor powder coating). As a result, it is preferable that the first predetermined value is specified as a value (e.g., 20) smaller than the upper limit (30) of the allowable range (e.g., 0 to 30) where the powder coating can be performed on the projecting portion4dof the multiple coil segments4. Specifically, the notification at the time of the computed index value exceeding the first predetermined value is intended to notify that immediate replacement of the first porous plate21is not necessary but the time of replacement is approaching.

When the control unit18has determined that the computed index value is equal to or less than the first predetermined value, the control unit18performs the powder coating on the coil segment4of the next stator1and, performs again the computation of the index value and the determination. When the control unit18has determined that the computed index value is equal to or less than the first predetermined value, the control unit18repeatedly performs the powder coating step and the computation and determination step.

When the control unit18has determined that the computed index value exceeds the first predetermined value, the control unit18issues the notification (predetermined notification) to output a sound indicating that the computed index value exceeds the first predetermined value from the speaker32. It should be noted that in addition to or in place of the notification by the speaker32, the notification may be provided by being displayed on a display unit (not shown) as a notification unit.

More specifically, the control unit18outputs a sound that urges replacement of the first porous plate21and the second porous plate22from the speaker32. Also, in accordance with the status of the above-described notification, a step may be provided for performing the notification urging replacement of the first porous plate21and the second porous plate22(a notification that is the same as or different than the above-described notification). It should be noted that the notification is not limited to the one that urges the replacement. In any case, a notification should be provided which indicates that the computed index value exceeds the first predetermined value.

Further, when it has been determined that the computed index value exceeds the first predetermined value, the stator1is conveyed to the outside of the moving path by the stator moving mechanism19. In addition, whether or not the powder resins15are sufficiently applied to the projecting portion4dof the coil segment4is confirmed by the operator or a not-shown check device.

When the control unit18has determined that the computed index value exceeds the preset second predetermined value, the control unit18outputs an actuation stop signal to the stator moving mechanism19such that the stator moving mechanism19is not actuated.

In this embodiment, the control unit18functions as a signal output unit configured to output an insertion stop signal for stopping the insertion of the coil segment4into the powder fluidizing tank16. It should be noted that the determination of whether or not the computed index value exceeds the second predetermined value and the output of the actuation stop signal may be omitted.

When the audio output and the actuation stop signal output should be stopped, the operator operates the display unit. Accordingly, the fact that the clogging of the first porous plate21occurs can be effectively and reliably notified to the operator.

The second predetermined value can be modified as appropriate as long as it falls within a range of values larger than the first predetermined value. The second predetermined value is preferably a value near the upper limit (30) of the allowable range (0 to 30). When the second predetermined value is a value (e.g., 28) near the upper limit (30) of the allowable range (0 to 30), then the notification in the case where the computed index value exceeds the second predetermined value is intended to notify the fact that the first porous plate21and the second porous plate22need to be immediately replaced.

When the control unit18has determined that the computed index value exceeds the second predetermined value, the control unit18may continue the notification to the effect that the first porous plate21and the second porous plate22should be replaced from the speaker32and the output of the actuation stop signal until the first porous plate21and the second porous plate22are replaced. By virtue of this, it is made possible to effectively and reliably suppress poor powder coating because the powder coating is not performed on the coil segment4of the next stator1until the first porous plate21and the second porous plate22are replaced.

It should be noted that, while in the above-described embodiment, the heights of the surface of the powder resins15are measured at the eight locations where the projecting portions4dof the eight coil segments4are inserted and the index value indicative of the dispersion of the eight measurement results is computed, the locations of the measurement are not limited to the regions where the projecting portions4dof the eight coil segments4are inserted. The locations of measurement may be identified anywhere on the surface of the powder resins15. For example, the heights of the surface of the powder resins15at the region traversing the central axis of the powder fluidizing tank16and the height of the surface of the powder resins15in the coil insertion range CA may be measured and a difference between them may be computed as the index value.

While the present invention is implemented on the inspection device35that inspects the height of the surface of the powder resins15for the powder coating on the projecting portion4dof the coil segment4in the above-described embodiment, the object to be subjected to the powder coating is not limited to the projecting portion4dof the coil segment4and the present invention can be implemented on inspection devices that inspect the height of the surface of the powder resins for powder coating on various workpieces.