JPH04769B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention is an automatic assembly device, and in particular, a system that selects a shim thickness closest to the required tightening amount from among a plurality of shims having different thicknesses according to the required tightening amount of the part to be attached to the object to be attached. The present invention relates to an automatic assembly device that selects a shim of a certain thickness, interposes the selected shim between the assembly component and the object to be attached, and threads the assembly component. <Prior art> As shown in FIG. 1, a valve seat member 2 is screwed into the open end of a bottomed hole 1a formed in a housing 1,
Between this valve seat member 2 and the bottom surface of the bottomed hole 1a, there is a valve body 3 that contacts a valve seat 2b formed in the valve seat member 2 to open and close the communication passage, and a valve body 3 that opens and closes a communication passage. In a flow control valve with a built-in relief valve configured with a seat member 4 and a spring 5 that press toward the side, the relief pressure changes due to dimensional variations in the valve seat member 2 and variations in the elastic force of the spring 5. do. For this reason, the valve seat member 2
It is necessary to interpose a copper shim 6 between the valve seat member 2 and the housing 1 to adjust the position of the valve seat member 2 so that the relief pressure is constant. Conventionally, in the installation process of this type of valve assembly, in order to keep the relief pressure (operating pressure) of the valve assembly constant, a shim of a predetermined thickness is assembled to each valve assembly for each lot and this is used as a relief. Tests were performed using a test stand for pressure confirmation, and if the specified relief pressure was not obtained, the worker would reassemble the shim. As a result, selecting and assembling shims took a lot of time, resulting in extremely low work efficiency. In order to automatically select the shim, as shown in Fig. 2a and b, the valve body 3 is moved back until the spring 5 generates a repulsive force corresponding to the relief pressure. The top and the opening end surface 1b of the housing 1
While measuring the distance B between the valve seat member 2 and
An engaging ball 7 having the same shape as the valve body 3 is engaged with the valve seat 2b, and the distance H between the flange lower surface 2a, which is the seating surface of the valve seat member 2 against the housing 1, and the top of the engaging ball 7 is determined. The shims may be selected based on the dimensional difference between the distances H and B. However, while the possible values of the dimensional difference between the distances H and B are infinite, it is not possible to prepare so many types of shims in order to avoid complicating and increasing the size of the parts supply device. However, there was a problem in that the relief pressure of the assembled relief valve increased in variation. <Purpose of the Invention> Therefore, the present invention aims to increase the final tightening torque of the assembled parts to increase the crushing margin of the shim when the thickness of the selected shim is thicker than the theoretically required shim thickness. The position of the assembled part after tightening can be brought closer to the required position by the shim, and the position between the assembled part after tightening and the required position can be adjusted without increasing the number of shims. The purpose of this is to reduce the misalignment. <Configuration of the Invention> FIG. 3 is an overall configuration diagram for clearly explaining the present invention. The screw tightening device A that screws the assembly part 2 onto the object to be attached 1 is provided with a torque detector B that detects the tightening torque by the screw tightening device A, and the screw tightening control means C is equipped with a torque detector B that detects the tightening torque by the screw tightening device A. When the torque detected by device B reaches a set value VR, the screw tightening operation of screw tightening device A is stopped. On the other hand, as the set value VR, for example, a first set value VR1 corresponding to normal tightening torque and a second set value VR2 which is a value larger than this first set value VR1 by a predetermined amount are set in advance, and the discrimination Means E
The torque changing means D supplies either the first set value VR1 or the second set value VR2 to the screw tightening control means C in response to a command from the screw tightening control means C. Then, the determining means E compares the theoretical required shim thickness Tt corresponding to the required tightening amount of the assembly part 2 with the actually selected thickness Tr of the shim 6, and determines the theoretical required shim thickness Tt. If the selected shim thickness Tr is the same or thinner, the torque changing means D selects the first set value VR1, and if the selected shim thickness Tr is thicker than the theoretical required shim thickness Tt. The second set value VR2 is selected by the torque changing means D. As a result, when the selected shim thickness Tr is thicker than the theoretically required shim thickness Tt, the screw tightening torque by the screw tightening device A is increased, and the crushing margin after tightening the shim 6 is increased. The position of the seat member 2 after tightening is brought closer to the required tightening position. <Example> Hereinafter, an example of the present invention will be described based on the drawings regarding an example in which a flow control valve having a built-in relief valve is automatically assembled. Figure 4 shows the post-process part of the automatic assembly line, where 10 is a measuring station, 11a to 11
d shows a plurality of shim supply devices, 12 shows a screw tightening device, P1 shows a parts temporary storage stand, and P2 shows a finished product temporary storage stand. As shown in FIG. 2a, a robot (not shown) is placed on the parts temporary storage stand P1 in the pre-process on the housing 1 and the valve seat member 2 in which the spring 5, the seat member 4, and the valve body 3 are assembled. Translated by
The housing 1 and the valve seat part 2 are first transferred by the robot 13 to the measuring station 10 . At this measuring station 10, measurements are taken to determine the required tightening position of the valve seat member 2, and the shim thickness is determined based on this. After this, the robot 13 moves to the measuring station 1.
After transferring the housing 1 from the shim 0 to the screw tightening device 12, one of the shims supplied by the shim supply devices 11a to 11d is selected and placed on the upper surface of the housing 1 being transferred into the screw tightening device 12. Place,
Further, the valve seat member 2 is taken out from the measuring station 10 and transferred into the screw tightening device 12 to position the valve seat member 2 at the upper end of the inner hole of the housing 1. After that, the valve seat member 2 is positioned at the upper end of the inner hole of the housing 1 by the operation of the screw tightening device 12. Part 2
After tightening, the assembled housing 1 is transferred to the finished product temporary storage stand P2. Next, the configuration of the measuring station 10 will be explained based on FIGS. 5 to 7. A jig 21 for mounting the housing 1 and the valve seat member 2 is attached to the base 20. A measuring rod 31 is disposed at a position facing the housing 1 placed on the jig 21 above.
A pressing member 41 is disposed above the valve seat member 2 placed on the valve seat member 1 . The measuring rod 31 is assembled with its upper end integrally connected to a measuring member 32 provided inside the measuring head 30 so as to be movable in the vertical direction. The measuring head 30 is integrally fixed to the front surface of the sliding body 24. Sliding body 24
is attached to the entire surface of a column 25 erected on one side of the base 20 so as to be slidable in the vertical direction, and can be moved up and down by a cylinder 26 attached to the upper part of the column 25. At the top inside the measuring head 30, there is a feed screw 3.
A movable member 34 is connected to a pulse motor 36 through a motor 5, and is moved up and down by the rotation of the pulse motor 36. A master spring 33 is connected between the movable member 34 and the measuring member 32.
is installed. Further, a displacement detector X for detecting the amount of deflection of the master spring 33 is provided between the movable member 34 and the measuring member 32, and a displacement detector A position detector Y is provided to detect the position of the measuring member 32 relative to the position of the measuring member 32. On the other hand, the pressing member 41 is connected to the measuring head 30 mentioned above.
It is formed at the lower end of a rod 42 which is attached to one side of the sliding body 24 so as to be movable in the vertical direction, and is urged downward by a spring 43.
It is prevented from coming off by a nut 42a fastened to the upper end of 2. Below the mounting hole in the jig 21 to which the valve seat member 2 is mounted, a displacement detector Z is mounted, in which an engagement ball 7 having the same diameter as the valve body 3 is mounted on the tip of a feeler Zf. When the valve seat member 2 is inserted into the mounting hole of the tool 21, the engaging ball 7 engages with the valve seat 26 of the valve seat member 2. In the measuring station 10 constructed as described above, the housing 1 and the valve seat member 2 are each set on the jig 21 by the carrier hand 13a of the robot 13, as shown by imaginary lines in FIG. In this state, when the cylinder 26 is activated by a command signal from the measurement control device 60, which will be described later, the sliding body 24 moves downward by the driving force and stops at its lowering end. As a result, the housing 1 is positioned and fixed as shown in FIG. 2a by contact with the lower end surface of the measuring head 30, and the lower end surface of the measuring rod 31 is brought into contact with the top of the valve body 3 in the housing 1. come into contact with Next, the pulse motor 36 located at the upper end of the measurement head 30 is activated in response to a command signal from the measurement control device 60, and the pulse motor 36 is operated until the master spring 33 generates a spring force responsive to a predetermined set pressure (relief pressure). , lowers the movable member 34. In other words, the spring force of the master spring 33 is the product of the relative displacement amount ΔX of the detection member 32 with respect to the movable member 34 detected by the displacement detector X by the spring constant K of the master spring 33. The movable member 34 is lowered until the output value of the detector X becomes a value obtained by dividing the spring force with respect to the set pressure by a constant K. Then, by reading the output value of the position detector Y at that time, the spring 5
This means that the distance B between the open end surface 1b of the housing 1 and the top surface of the valve body 3 with a predetermined mounting load applied thereto is detected. On the other hand, due to the lowering of the sliding body 24, the pressing member 4
1 also descends, and the descending surface of the pressing member 41 touches the valve seat member 2.
The lower surface 2a of the flange of the valve seat member 2 is pressed against the upper surface of the jig 21. As a result, the feeler Zf of the displacement detector Z in the jig 21 is lowered according to the position of the valve seat 2a of the valve seat member 2, and the distance H between the flange lower surface 2a of the valve seat member 2 and the top of the engagement ball 7 is lowered. is measured by displacement detector Z. The subtraction means provided in the measurement control device 60 subtracts the interval 8B from the interval H based on the measurement result, and outputs the value for the difference (t=X-B) as the required shim thickness Tt. Next, the configuration of the screw tightening device 12 will be explained based on FIGS. 8 and 9. A jig 51 fixed to the base 50 has a mounting hole for placing the screw 1, and A nut runner 53 is disposed above the jig 51 and is moved up and down by a cylinder device 52. That is, the base 50
A movable table 56 that is moved up and down by the cylinder device 52 is guided by a support 55 erected on one side.
A nut runner 53 is attached to this movable base 56. The internal structure of this nut runner 53 is the same as that of a known nut runner, so it will not be described in detail, but a socket 58 that engages with an engagement surface formed on the outer peripheral surface of the nut runner 57 is attached to the output shaft 57 so as to be able to move axially. and is pressed upward by a spring (not shown). The nut runner 53 is connected to a movable table 56 at its lower end, and is formed with a flexible portion 53a with a thinner casing above the connecting portion. Twisting occurs in the flexible portion 53a. A semiconductor strain gauge 59 for detecting the amount of twist of the flexible portion 53a is attached to the flexible portion 53a, and the flexible portion 53a and the semiconductor strain gauge 59 constitute a torque detection mechanism 54. The output of the semiconductor strain gauge 59 is supplied to a screw tightening control circuit 61 shown in FIG.
1 is a set value at which the torque detected by the torque detection mechanism 54 is supplied from the central control device 62.
Natsutranna 5 until VR1 or VR2
The drive motor 53b of No. 3 is operated, and the detected torque St
When the value reaches the first set value VR1 or the second set value VR2, the drive motor 53b is stopped and the screw tightening operation is completed. Next, the operation of the central control device 62 shown in FIG. 10 will be explained. This central control device 62 is constituted by a computer, and is connected to the measurement control device 60 and the screw tightening control circuit 61 via an unillustrated interface circuit.
It is connected to a robot control circuit 63 that controls the operation of the robot 13, and controls shim selection and changes in tightening torque according to a program stored in an internal memory. Now, the housing 1 and the valve seat member 2 of the temporary component stand P1 are transferred to the measurement station 10, and the measurement station 10 measures the above-mentioned distances H and B. Based on this, the measurement control device 60 controls the difference between H and B. If the value of is output as the required shim thickness Tt,
The central controller 62 executes the program shown in FIG. When this program is run, the first thing it does is
The robot control circuit 63 is instructed to transfer the housing 1 that has been measured at the measurement station 10 to the jig 51 of the screw tightening device 12 (), and when this operation is completed, the required shim thickness output from the measurement control device 60 is Read Tt data (), and based on this select the shim with the thickness closest to the required shim thickness Tt, and decide whether to use normal tightening torque or heavy tightening torque for the tightening force (a) ~
(d).

[Table] Table 1 shows the shim thickness to be selected corresponding to the required shim thickness Tt, the required shim thickness range for tightening with normal tightening torque, and the range of required shim thickness for tightening with a stronger tightening torque. This indicates the range of required shim thickness to be performed, and the range of required shim thickness Tt is determined by steps (a) to (h), and the dimension in which the selected shim thickness Tr is thicker than the required shim thickness Tt is determined. If it belongs to the range 0.25 to 0.3, …0.55 to 0.6 (
In steps a) and (d), set the strong tightening flag STF, and if the required shim thickness Tt is not within the above dimension range, reset the strong tightening flag STF in steps (a) to (d). Once this process is completed, the required shim thickness Tt
A command signal is given to the robot control circuit 63 to select the shim 6 corresponding to the range to which it belongs (a)
~(d). As a result, the robot 13 takes out the selected shim 6 from the corresponding one of the shim supply devices 11a to 11d and places it on the housing 1 carried by the jig 51 of the screw tightening device 12. When this operation is completed, the central controller 62 gives different operation commands to the robot control circuit 63 to bring the valve seat member 2 in the measuring station 10 to the upper part of the housing 1 in the screw tightening device 12, and to The lower end is engaged with the opening end of the inner hole of the housing 1 (), and after this, the central control device 62 determines whether the strong tightening flag STF is set (), and determines whether the strong tightening flag STF is set. If not, the first setting value VRI corresponding to the normal tightening torque is sent to the screw tightening control circuit 61, a start command is given to the regular tightening control circuit 61 (a), and the strong tightening flag STF is set. If so, a second set value VR2, which is larger than the first set value VR1 by a certain amount, is output to the screw tightening control circuit 61 to send out a start command (b). As a result, the screw tightening control circuit 61 operates the cylinder 52 to lower the nut runner 53 to connect the socket 58 to the valve seat member 2, and then energizes the drive motor 53b to tighten the valve seat member 2. . Then, the tightening torque by the nut runner 53 is set to the first set value VR1 or the second set value VR.
2, the drive motor 53b is deenergized, the nut runner 53 is raised, and the screw tightening is completed. Note that additional tightening may be performed by a certain amount after the tightening torque reaches the first set value VR1 and the second set value VR2. In this case, if the selected shim thickness Tr is thicker than the required shim thickness Tt, the central controller 62 will issue a second set value VR2 that is larger than the first set value VR1 corresponding to the normal tightening torque. is supplied, the crushing margin of the shim 6 after tightening the valve seat member 2 becomes large, and the normal tightening performed when the selected shim thickness Tr is the same or slightly thinner than the required shim thickness Tt. The thickness of the shim after tightening can be made thinner than in the case where the shim is tightened. Therefore, if the selected shim thickness Tr is thicker than the required shim thickness Tt, the shim thickness will be brought closer to the required shim thickness Tt, and the It becomes possible to bring the position closer to the requested position. This results in
The fluctuation width of the relief pressure of the assembled relief valve can be reduced. In addition, in the above embodiment, the required shim thickness Tt
The tightening torque was changed to two levels, normal tightening torque and strong tightening torque, depending on the dimensional range of the shim, but as shown in Figure 12, the required shim thickness
If the selected shim thickness Tr is thicker than Tt, the second set value VR2 is calculated using equation (1) based on the difference between the required shim thickness Tt and the selected shim thickness Tr.
b)' This calculated second set value VR2 may be supplied to the screw tightening control circuit 61. VR2=VR1+K(Tr-Tt)...(1) However, K is a constant determined by experiment. In addition, as the thickness of the shim increases, the amount of decrease in thickness relative to the increase in tightening torque increases slightly, so as shown in equation (2), the thicker the selected shim, the more The second set value VR2 may be calculated using a formula including a correction term that reduces the amount of increase in torque. VR2=VR1+K(Tr-Tt)-L·Tr (2) However, L is a constant determined experimentally. Further, the screw tightening control device 61 is configured to tighten a predetermined amount after the tightening torque exceeds a set value, and when the thickness Tr of the selected shim is thicker than the required shim Tt, this tightening amount The predetermined amount for determining the amount may be increased. In this case, the central controller 62 determines whether the selected shim thickness Tr is thicker than the required shim thickness Tr,
If the screw is thick, it operates by giving a command signal to the screw tightening control device 61 to increase the predetermined amount. Note that the present invention can be applied not only to the assembly of a relief valve device, but also to the assembly of other parts as long as a shim is used to adjust the position of the assembled part with respect to the object to be fastened. I can do it. <Effects of the Invention> As described above, in the present invention, when the selected shim thickness is thicker than the theoretically required shim thickness, the final tightening torque of the assembled parts is increased to prevent shim collapse. By increasing the width, the position of the assembled parts after tightening can be brought closer to the required position, so the position of the assembled parts after tightening can be adjusted without increasing the types of shims. can be brought closer to the required position. Therefore, by using the present invention for assembling a relief valve, etc., it is possible to assemble the relief valve without complicating the device.
This has the advantage that variations in valve characteristics can be reduced and more reliable assembly can be performed.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a flow control valve with a built-in relief valve, FIGS. 2a and 2b are measurement state diagrams for explaining the principle of determining the required thickness of the shim 6 in FIG. The figure is an overall configuration diagram to clarify the present invention, Figures 4 to 12 show embodiments of the present invention, Figure 4 is a schematic plan view of an assembly line, and Figure 5 is the same as Figure 4. FIG. 6 is a vertical cross-sectional view showing the configuration of the measurement station 10 in FIG.
7 is a cross-sectional view taken along the line - in FIG. 5, FIG. 8 is a side view showing the configuration of the screw tightening device 12 in FIG. 4, and FIG. 10 is a block diagram showing the control circuit, FIG. 11 is a flowchart showing the operation of the central control device 62 in FIG. 10, and FIG. It is a flowchart showing a modification. 1...Housing, 2...Valve seat member, 10...
Measuring station, 11a-11b...Shim supply device, 12...Screw tightening device, 13...Robot, 53...Nut runner, 54...Torque detection mechanism, 59...Semiconductor strain gauge, 60...Measurement control device, 61...Screw tightening control circuit, 62...Central control device.

Claims (1)

[Scope of Claims] 1. Selecting a shim with a thickness closest to the shim thickness corresponding to the required tightening amount from a plurality of shims having different thicknesses according to the required tightening amount of the assembled part to the object to be attached, In an automatic assembly device in which the selected shim is interposed between the assembly component and the object to be attached and the assembly component is threaded, the selected shim is selected in comparison with the required shim thickness corresponding to the required tightening amount. a determining means for determining whether the thickness of the selected shim is thick or not; and in response to the determining means, if the thickness of the selected shim is thicker than the required shim thickness, the tightening torque by the screw tightening device is increased. An automatic assembly device characterized by comprising a tightening torque increasing means for increasing the tightening torque. 2. The tightening torque increasing means includes tightening torque detecting means for detecting the tightening torque of a screw tightening device that tightens the assembled parts, and tightening the screw of the screw tightening device when a detected value by the torque detecting means exceeds a set value. The shim is characterized by comprising a control means for stopping the operation, and a set value changing means for increasing the set value when the thickness of the selected shim is thicker than the required shim thickness in response to the determining means. An automatic assembly device according to claim 1. 3. The tightening torque increasing means includes tightening torque detecting means for detecting the tightening torque of a screw tightening device that tightens the assembled parts, and tightening by a predetermined amount after the detected value by this torque detecting means exceeds a set value. a control means for stopping the screw tightening operation of the screw tightening device when the screw tightening operation is performed, and a control means corresponding to the discrimination means,
2. The automatic assembly apparatus according to claim 1, further comprising tightening amount changing means for increasing the predetermined amount when the thickness of the selected shim is thicker than the required shim thickness.