JP5350511B2 - Screw tightening device - Google Patents

Description

  The present invention relates to a screw tightening device used in an assembly process of various watt-hour meters installed in electric power consumers such as general households and factories.

  For example, as a watt hour meter that measures and displays the amount of power used by power consumers such as ordinary households, shops, factories, and buildings, the disk rotates according to the amount of power used to indicate the amount of power used There is an electronic watt-hour meter equipped with an electronic circuit in order to easily cope with the diversification of a mechanical watt-hour meter and an electric transaction menu (for example, see Patent Document 1).

  This type of watt-hour meter is a resin terminal block in which a resin base with internal components assembled is housed in an upper part of a metal case, and a lead-in line from a power transmission system and a customer side wiring are connected Has a structure fixed to the lower part of the case.

  In this watt-hour meter, a conductive plate electrically connected to internal components is provided on a base accommodated in the upper part of the case, and a lead-in wire and a customer are connected to a terminal block fixed to the lower part of the case. A conductive plate to which the side wiring is connected is provided. By connecting the conductive plate of the base and the conductive plate of the terminal block with screws, the internal components and the terminal block are electrically connected.

  For example, as shown in FIGS. 9 and 10, a screw insertion hole 7 is formed through the terminal block side end of the conductive plate 6 of the base 1. A hole 8 is formed in communication with the hole 7 of the conductive plate 6. The hole 8 of the base 1 has a larger diameter than the hole 7 of the conductive plate 6. On the other hand, a screw hole 10 for screwing is formed at the base side end of the conductive plate 9 of the terminal block 3.

  When the watt hour meter is assembled, the screw 11 is connected to the hole 8 of the base 1 and the conductive portion in a state where the terminal block side end of the conductive plate 6 of the base 1 and the base side end of the conductive plate 9 of the terminal block 3 are overlapped. The conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3 are connected by being inserted into the hole 7 of the plate 6 and screwed into the screw hole 10 of the conductive plate 9 of the terminal block 3 and seated on the conductive plate 6. They are connected electrically.

JP 2007-1114025 A

  By the way, in the assembly process of the watt-hour meter described above, it is possible to save labor by using an automatic screw tightening device for screw tightening for electrically connecting the conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3. I try to figure it out. In the conventional screw tightening device, the screw 11 is tightened by the following procedure.

  First, the terminal block side end of the conductive plate 6 of the base 1 and the base side end of the conductive plate 9 of the terminal block 3 are overlapped. At this time, the base 1 and the terminal block 3 are fixed in a state of being positioned on a base (not shown). On the other hand, the screw 11 held by the electric screwdriver is positioned with respect to the hole 8 of the base 1 and the hole 7 of the conductive plate 6 and the screw hole 10 of the conductive plate 9 of the terminal block 3. From this state, the electric driver is brought close to the base 1 and the terminal block 3, and the screw 11 attached to the electric driver is inserted into the hole 8 of the base 1 and the hole 7 of the conductive plate 6, and the conductive plate of the terminal block 3. 9 is screwed into the screw hole 10 to be seated on the conductive plate 6.

  In the watt-hour screw tightening process as described above, positioning errors when the base 1 and the terminal block 3 are fixed on the base, and positioning when the electric driver is disposed above the base 1 and the terminal block 3 are performed. There is an error. There is also an assembly tolerance when the base 1 and the terminal block 3 are assembled. Due to the positioning error of the base 1 and the terminal block 3, the positioning error of the electric driver, and the assembly tolerance of the base 1 and the terminal block 3, the hole 8 and the conductive plate 6 of the base 1 are located with respect to the screw position attached to the electric driver. An error is accumulated in the relative position between the hole 7 and the screw hole 10 of the conductive plate 9 of the terminal block 3.

  In the conventional screw tightening device, since the base 1 and the terminal block 3 are fixedly arranged with respect to the electric driver, the tightening operation of the screw 11 is electrically performed with the above-described error occurring. If it is executed by a driver, screw looseness due to screw caulking or oblique tightening occurs. When such screw caulking or screw floating failure occurs, there is a problem that the yield is greatly reduced and the reliability of the product is also greatly reduced.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to suppress the occurrence of screw galling and screw floating failure during screw tightening operation in the watt-hour meter assembly process. An object of the present invention is to provide a screwing device that can be used.

As a technical means for achieving the above-described object, the screw tightening device according to the present invention is mounted on a fixedly arranged base and support means attached to the base so as to be movable in the X and Y directions. A movable base on which an object is detachably positioned, a restoring means provided between the base and the movable base and returning the movable base to an initial position with respect to the base, and a Z-direction movement with respect to the movable base And an electric driver that performs a screw tightening operation on a screw hole of an object to be tightened that is positioned on the movable base, and the support means is a ball roller that supports the movable base in a point contact state. The restoring means is a coil spring stretched between the base and the movable base in each of the X direction and the Y direction, and the tightening object is derived from a terminal block attached to the case of the watt hour meter. With conductive plate Characterized in that it is composed of two members made of the other conductive plate derived from a base which is attached to the case.

  In the present invention, a movable base is mounted on a fixedly arranged base so as to be movable in the X and Y directions via a support means, and an object to be tightened is positioned on the movable base. A screw tightening operation is performed on the screw hole of the object to be tightened by an electric screwdriver that is movably provided.

  When this screw is tightened, even if there are positioning errors of the object to be tightened with respect to the base, positioning errors of the electric screwdriver with respect to the object to be tightened, and assembly tolerances of the object to be tightened, the movable base on which the object to be tightened is positioned is XY. Since the direction is movable, the screw hole of the object to be tightened is automatically adjusted with respect to the screw of the electric driver. By such simple means, the screw of the electric screwdriver can be screwed into the screw hole of the object to be tightened with an optimal posture to ensure a good tightening state. Generation | occurrence | production can be suppressed.

  Note that if the electric screwdriver is removed from the screw after the screw tightening operation is completed, the movable base can be automatically returned to the initial position with respect to the base by the restoring means. And quick transition to the standby state becomes possible.

Support means in the present invention shall be the ball rollers for supporting the movable table in a point contact state. Thus by Rukoto to adopt a ball roller as a supporting means for supporting the movable table in a point contact state, the movable stand can be XY direction movably mounted against the base with a simple structure, the electric The position of the screw hole of the object to be tightened can be smoothly adjusted with respect to the screw of the driver.

Restoration means in the present invention, Ru coil Banetosu which is stretched in each of X and Y directions between the base and the carriage. Thus by Rukoto to adopt coil spring as restoring means for returning the carriage to its initial position relative to the base, the movable table can be restored to the initial position relative to the base with a simple structure, A quick transition to the standby state can be smoothly performed for the next tightening object.

  In the present invention, a structure is preferably provided in which stopper means for restricting the range of movement of the movable base relative to the base is provided between the base and the movable base. In this way, if the stopper means for regulating the moving range of the movable base relative to the base is provided between the base and the movable base, it is possible to prevent the movable base from moving excessively with respect to the base, so that the movable base is movable. The table can be quickly returned to the initial position, and work efficiency can be improved.

The object to be tightened in the present invention is composed of two members consisting of one conductive plate derived from a terminal block attached to the case of the watt hour meter and the other conductive plate derived from a base attached to the case. The The Rukoto to adopt this way the two conductive plates of the terminal block and the base attached to the power meter as clamping object positioned on the movable platform, to ensure good fastening state in the assembly process of the power meter Therefore, it is effective in that it is possible to suppress the occurrence of screw galling or screw floating failure.

According to the present invention, a fixedly arranged base, a movable base that is placed on the support means attached to the base so as to be movable in the X and Y directions, and in which the object to be tightened is detachably positioned, and the base, Restoring means provided between the movable base and returning the movable base to the initial position with respect to the base, and a screw of the tightening object positioned on the movable base, provided to be movable in the Z direction with respect to the movable base An electric driver that performs a screw tightening operation with respect to the hole , the support means is a ball roller that supports the movable base in a point contact state, and the restoring means is between the base and the movable base in the X direction. And a coil spring stretched in each of the Y direction, and the object to be tightened is one conductive plate derived from the terminal block attached to the wattmeter case and the other derived from the base attached to the case. With conductive plate By being configured in Ranaru two members, when tightening the screw, the positioning error of the object tightened with respect to the base, and positioning errors of the electric driver for object tightened, even if the assembly tolerance of the clamping object, its Since the movable base on which the tightening object is positioned is movable in the X and Y directions, the position of the screw hole of the tightening object is automatically adjusted with respect to the screw of the electric driver.

  By such simple means, the screw of the electric screwdriver can be screwed into the screw hole of the object to be tightened with an optimal posture to ensure a good tightening state. Generation | occurrence | production can be suppressed. As described above, since it is possible to suppress the occurrence of screw galling or screw floating failure during the screw tightening operation, workability can be improved, and the yield and reliability of the product can be greatly improved.

It is a schematic front view which shows the whole structure of the screw fastening apparatus in embodiment of this invention. It is a top view of FIG. It is a front view which shows the state which positioned the fastening target object in the screw fastening apparatus. FIG. 4 is a side view of FIG. 3. 3A and 3B are views for explaining a screw tightening operation from the state of FIG. 3, in which FIG. 3A is an enlarged sectional view of a main part showing a screw tightening operation start state, and FIG. It is sectional drawing. 4A and 4B are diagrams for explaining a screw tightening operation from the state of FIG. 4, in which FIG. 4A is an enlarged sectional view of a main part showing a screw tightening operation start state, and FIG. It is sectional drawing. It is a principal part expanded sectional view which shows the specific example of a stopper means. FIG. 8 is a plan view of FIG. 7. It is a principal part expanded sectional view which shows the state before the screw fastening operation | movement start in the past. It is a principal part expanded sectional view which shows the state after the screw fastening operation | movement start in the past.

  An embodiment of a screw tightening device according to the present invention will be described in detail below. In the following embodiments, an electronic watt-hour meter that measures and displays the amount of power used by a power consumer such as a general household, a store, a factory, or a building is exemplified as an object to be tightened. However, the present invention is also applicable to mechanical watt-hour meters such as electric utility meters, proof transaction meters, and general meters.

  As shown in FIGS. 3 and 4, the watt-hour meter as the tightening object (assembly body) of the screw tightening device of the present invention has a resin base 1 with internal components assembled on the upper part of a metal case 2. A resin terminal block 3 to be housed and to which a lead-in line from the power transmission system and a customer-side wiring are connected is fixed to the lower portion of the case 2.

  In this watt-hour meter, a conductive plate 6 electrically connected to internal components is provided on the base 1 accommodated in the upper part of the case 2, and the terminal block 3 fixed to the lower part of the case 2 is attached to the terminal block 3. A conductive plate 9 that is electrically connected to the lead-in line and the customer side wiring is provided. By connecting the conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3 with screws 11, the internal components and the terminal block 3 are electrically connected.

  A screw insertion hole 7 is formed through the terminal block side end of the conductive plate 6 of the base 1. Correspondingly, a screw insertion hole 8 communicates with the hole 7 of the conductive plate 6 in the base 1. Is formed. The hole 8 of the base 1 has a larger diameter than the hole 7 of the conductive plate 6. On the other hand, a screw hole 10 for screwing is formed at the base side end of the conductive plate 9 of the terminal block 3 (see FIGS. 9 and 10).

  In the watt-hour meter assembling process, the screw 11 is inserted into the hole 8 of the base 1 and the end of the conductive plate 6 of the base 1 and the end of the conductive plate 9 of the terminal block 3 are overlapped with each other. The conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3 are inserted into the holes 7 of the conductive plate 6 and screwed into the screw holes 10 of the conductive plate 9 of the terminal block 3 and seated on the conductive plate 6. Are electrically connected.

  In the assembly process of the watt-hour meter, the conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3 are electrically connected to each other in the assembly body (the structure in which the base 1 and the terminal block 3 are assembled to the case 2). An automatic screw tightening device for performing screw tightening for the purpose will be described in detail below with reference to FIGS.

  As shown in FIGS. 1 and 2, the automatic screw tightening device is placed on a rectangular plate base 21 fixedly arranged and support means attached to the base 21 so as to be movable in the X and Y directions. An assembly 12 (see FIG. 3 and FIG. 4) of a watt hour meter that is an object to be tightened is provided between a rectangular flat plate-like movable base 22 and a base 21 and the movable base 22; A restoring means for returning the movable base 22 to the initial position with respect to the base 21 and a screw hole 10 of the assembly body 12 provided to be movable in the Z direction with respect to the movable base 22 and positioned on the movable base 22 And an electric driver 23 for performing a screw tightening operation.

  Here, the screw hole 10 of the object to be tightened is a state where the terminal side end of the conductive plate 6 of the base 1 and the base side end of the conductive plate 9 of the terminal block 3 are overlapped as described above. It means the screw hole 10 of the conductive plate 9 of the terminal block 3 into which the screw 11 is inserted and screwed into the hole 8 of the base 1 and the hole 7 of the conductive plate 6.

  The aforementioned support means is a ball roller 24 that supports the movable base 22 in a point contact state. The ball roller 24 enables the movable base 22 to move in the X and Y directions by rolling of the ball, and is installed at a total of five locations at the four corners and the center of the base 21. In this embodiment, five ball rollers 24 are installed, but the position and number thereof are arbitrary, and can be appropriately set according to the weight of the assembly body 12 set on the movable base 22 and the weight balance thereof. Good. The support means may be a structure other than the ball roller 24 as long as it can support the movable base 22 so as to be movable in the X and Y directions with respect to the base 21.

  The aforementioned restoring means is a coil spring 25 stretched between the base 21 and the movable base 22 in each of the X direction and the Y direction. The coil springs 25 return the movable base 22 to the initial position by elastic restoring force, and are installed at a total of eight locations, two on each side of the base 21 and the movable base 22. In this embodiment, eight coil springs 25 are installed, but the position and number thereof are arbitrary, and may be set as appropriate according to the weight of the assembly body 12 set on the movable base 22. For example, when the weight of the assembly body 12 is increased, the number of the coil springs 25 is increased, and when the weight of the assembly body 12 is decreased, the number of the coil springs 25 is decreased. The restoring means may be a structure other than the coil spring 25 as long as the movable base 22 can be returned to the initial position with respect to the base 21.

  A positioning block 26 for positioning and fixing the case 2 of the assembly body 12 is provided on the movable table 22 described above. The positioning block 26 is installed on each side of the movable base 22 so as to contact the four sides of the case 2. The positioning block 26 can be adjusted in position with respect to the movable base 22 by a screwing structure or the like so as to correspond to the shape and size of the case 2.

  The electric driver 23 performs a screw tightening operation on the base 1 and the terminal block 3 of the assembly body 12 positioned on the movable base 22 and is movable at a tightening position (fixed position in the XY direction). It is provided so as to be movable in the Z direction with respect to the base 22. A screw feeder (not shown) is installed in the vicinity of the screw tightening device, and the electric driver 23 picks up and holds the screw 11 from the screw feeder by moving in the XY direction. . The electric driver 23 can hold the screw 11 by, for example, an air adsorption method, a magnetic adsorption method, or a pressure feeding method.

  Next, in the assembly process of the watt-hour meter, a screw tightening operation for electrically connecting the conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3 by the automatic screw tightening device having the above-described structure. The procedure is detailed below.

  First, as shown in FIGS. 3 and 4, the assembly body 12 in which the base 1 and the terminal block 3 are assembled to the case 2 is set on the movable base 22. That is, each of the base 1 and the terminal block 3 is fixed to the case 2 by screwing or the like, and the terminal block side end of the conductive plate 6 of the base 1 and the base side end of the conductive plate 9 of the terminal block 3 are connected. The assembly body 12 in an overlapped state is positioned by the positioning block 26 of the movable base 22.

  As described above, the electric driver 23 that picks up and holds the screw 11 from the screw feeder (not shown) with respect to the assembly body 12 positioned on the movable base 22 in this manner is disposed above the movable base 22. Place in the tightening position. In this tightening position, the screw 11 is attached to the hole 8 of the base 1 and the conductive plate 6 in a state in which the terminal block side end of the conductive plate 6 of the base 1 and the base side end of the conductive plate 9 of the terminal block 3 are overlapped. It is located above the screw hole 10 of the conductive plate 9 of the terminal block 3 inserted through the hole 7 and screwed. From this state, the electric driver 23 is lowered in the Z direction, and the screw 11 held by the electric driver 23 is inserted into the hole 8 of the base 1 and the hole 7 of the conductive plate 6, and the screw of the conductive plate 9 of the terminal block 3. A tightening operation for screwing into the hole 10 is started.

  At the start of tightening of the screw 11 by the electric driver 23, the movable base 22 on which the assembly body 12 is positioned moves the ball roller 24 relative to the base 21, as shown in FIGS. 5 (A) and 6 (A). Therefore, even if there are positioning errors of the assembly body 12 with respect to the base 21, positioning errors of the electric driver 23 with respect to the assembly body 12, and assembly tolerances of the assembly body 12, these errors are reduced. By absorbing the screw hole 10 of the assembly body 12 with respect to the screw 11 of the electric driver 23, the position of the screw hole 10 with respect to the screw 11 can be matched with the screw 11.

  As described above, by adopting the ball roller 24 that supports the movable table 22 in the point contact state as the support means for supporting the movable table 22 in the point contact state, the movable table 22 with respect to the base 21 with a simple structure. Can be placed so as to be movable in the X and Y directions, and the position of the screw hole 10 of the assembly body 12 can be adjusted smoothly with respect to the screw 11 of the electric driver 23.

  By such simple means, the screw 11 of the electric screwdriver 23 is screwed into the screw hole 10 of the assembly body 12 with an optimal posture as shown in FIGS. 5 (B) and 6 (B). Since a good tightening state can be secured by sitting on the conductive plate 6, it is possible to suppress the occurrence of screw galling or screw floating failure.

  After completing the tightening operation of the screw 11, the electric driver 23 is lifted in the Z direction to be detached from the screw 11. When the electric driver 23 is detached from the screw 11 in this manner, the movable base 22 is automatically moved with respect to the base 21 by the elastic restoring force of the coil spring 25 stretched between the base 21 and the movable base 22. Thus, the initial position can be restored. Thus, the movable base 22 is automatically returned to the initial position by the coil spring 25, so that the next assembly body 12 can be quickly shifted to a standby state.

  In this automatic screw tightening device, as shown in FIGS. 7 and 8, stopper means for restricting the movement range of the movable table 22 relative to the base 21 is provided between the base 21 and the movable table 22. This stopper means has a structure in which a through hole 27 is formed at an arbitrary position of the base 21, a bolt 28 is inserted into the through hole 27 from the lower surface side of the base 21, and is screwed to the lower surface side of the movable base 22. It is said. In this structure, the region in which the bolt 28 screwed to the movable base 22 can move in the XY direction is the inner diameter D of the through hole 27 formed in the base 21. When the movable base 22 moves in the XY direction, the bolt 28 that moves in the XY direction as the movable base 22 moves contacts the inner diameter of the through hole 27 of the base 21, so that the movable range of the movable base 22 is reduced. Can be regulated.

  Thus, by providing the bolt 27 as a stopper means for restricting the moving range of the movable base 22 with respect to the base 21 between the base 21 and the movable base 22, the movable base 22 is excessive with respect to the base 21. Therefore, the movable base 22 can be quickly returned to the initial position, and work efficiency can be improved.

  The head 29 of the bolt 28 has an outer diameter d larger than the inner diameter D of the through hole 27 of the base 21. In this way, when the electric driver 23 is lifted in the Z direction after completion of the tightening operation of the screw 11, the screw 11 is caught by the electric driver 23 and the movable base 22 is lifted. Even if it is going to be lifted, the head 29 of the bolt 28 is locked to the peripheral edge of the through hole 27 of the base 21, so that the movable base 22 can be prevented from being lifted.

  In the above embodiment, the screw tightening in the case where the conductive plate 6 of the base 1 and the conductive plate 9 of the terminal block 3 are electrically connected has been described. However, the present invention is not limited to this, and the terminal It can also be applied to screw tightening of the block 3 alone.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

DESCRIPTION OF SYMBOLS 1 Base 2 Case 3 Terminal block 6 Conductive plate 9 Conductive plate 12 Tightening object (Assembly body of watt-hour meter)
21 base 22 movable base 23 electric driver 24 support means (ball roller)
25 Restoring means (coil spring)
28 Stopper means (bolts)

Claims (2)

A fixed base, a movable base mounted on a support means attached to the base so as to be movable in the X and Y directions, and an object to be tightened is detachably positioned; and the base and the movable base A restoring means for returning the movable table to an initial position with respect to the base; and a screw of an object to be clamped provided to be movable in the Z direction with respect to the movable table and positioned on the movable table An electric driver that performs a screw tightening operation on the hole, the support means is a ball roller that supports the movable base in a point contact state, and the restoring means includes the base and the movable base. Coil springs stretched in each of the X direction and the Y direction, and the object to be tightened is attached to one conductive plate led out from a terminal block attached to the case of the watt hour meter and the case. Screwing apparatus characterized by being composed of two members made of other conductive plate and derived from the base was. The screw tightening device according to claim 1 , wherein stopper means for restricting a moving range of the movable base relative to the base is provided between the base and the movable base.

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