JP7526679B2 - Damper - Google Patents

Description

The present invention relates to a damper that is attached between a power tool, such as an electric screwdriver, and an automated machine, such as an industrial robot, in order to mount the power tool on the automated machine.

Industrial robots that perform assembly work on production lines are equipped with electric screwdrivers to automatically tighten screws. During this process, there is a possibility that the position of the electric screwdriver mounted on the robot arm during screw tightening may deviate from the optimum position for screw tightening due to positioning errors in the robot arm, errors in the shape of the screw or screw hole, and discrepancies in the timing at which the screw engages with the screw hole. In particular, there may be a large deviation in the position of the screw tightening direction due to discrepancies in the timing at which the screw engages. This may result in the screw not being pressed against the screw hole with the appropriate force during screw tightening, which may result in poor screw tightening.

To solve the above problem, for example, in Patent Document 1, a spring-based buffer mechanism is provided between the electric screwdriver and the robot arm to absorb positional deviations in the screw tightening direction and to ensure that the force pressing the screw against the screw hole is within a certain range.

Patent No. 6550679

The optimal screw pressing force during tightening varies depending on the size of the screw to be tightened and the material of the workpiece. For this reason, it may be necessary to change the spring pressure of the spring in the buffer mechanism (damper). In the above-mentioned conventional technology, the electric screwdriver is also provided with a buffer mechanism that allows the spring pressure to be adjusted, but if the electric screwdriver is not provided with such a mechanism, the pressing force must be adjusted on the robot arm side. Since the buffer mechanism attached to the robot arm in the above-mentioned conventional technology does not have a mechanism for adjusting the spring pressure, the spring must be changed in order to change the spring pressure. However, such spring replacement work is troublesome, and it is also difficult to make fine adjustments to the spring pressure.

The present invention aims to provide a damper that can be installed between a power tool and an automatic machine and that allows for easy adjustment of spring pressure.

That is, the present invention provides:
A damper for mounting a power tool on an automated machine, comprising:
a first attachment member adapted to be attached to one of the power tool and the automated machine;
a second attachment member attached to the other of the power tool and the automatic machine, and displaceable from an initial position to an operating limit position relative to the first attachment member in a predetermined operating direction;
a shock absorbing mechanism portion disposed between the first mounting member and the second mounting member;
Equipped with
The buffer mechanism portion is
a holding portion fixedly disposed relative to the first mounting member;
a spring pressure adjusting member having a shaft portion formed with a male screw portion and arranged so as to be rotatable around a longitudinal axis of the shaft portion relative to the holding portion but not displaceable in the direction of the longitudinal axis;
a spring base having a female screw portion screwed into the male screw portion of the spring pressure adjusting member, the spring base being disposed so as to limit rotation relative to the holding portion, and being displaced in the direction of the longitudinal axis relative to the holding portion when the spring pressure adjusting member rotates;
a buffer spring that is set between the spring base and the second mounting member and is compressed when the second mounting member is displaced from the initial position toward the operating limit position to urge the second mounting member toward the initial position;
The present invention provides a damper having a

In this damper, the position of the spring base in the longitudinal axis direction can be changed by rotating the spring pressure adjustment member. This makes it possible to adjust the spring pressure generated by the buffer spring by changing the compression amount of the buffer spring set between the spring base and the second mounting member. In addition, although a force in the rotation direction may act on the spring base when the buffer spring expands or contracts, the spring base is arranged in a state in which its rotation is restricted relative to the holding part, so that the spring base does not rotate unintentionally and the spring pressure does not change. Furthermore, since the spring pressure adjustment member engages with the buffer spring via the spring base whose rotation is restricted, the force in the rotation direction from the buffer spring is not substantially transmitted. This makes it possible to prevent the spring base from being unintentionally displaced in the longitudinal axis direction due to the spring pressure adjustment member rotating relative to the holding part.

Also,
the buffer mechanism further includes a pressure spring that is set between the spring base and the holding portion and has a stronger biasing force than the buffer spring;
The spring pressure adjusting member has an engaging portion that engages with the holding portion from the opposite side of the pressure spring in the direction of the longitudinal axis,
The spring pressure adjusting member can maintain a state in which the engaging portion is pressed against the holding portion by the biasing force of the pressure spring, preventing the spring pressure adjusting member from being displaced in the direction of the longitudinal axis.

When the engaging portion of the spring pressure adjustment member is pressed against the retaining portion, frictional force is generated between the engaging portion and the retaining portion, making it possible to prevent the spring pressure adjustment member from rotating with a weak force. This makes it possible to more reliably prevent the spring pressure adjustment member from rotating unintentionally when it is subjected to vibration during operation or when the spring pressure adjustment member is accidentally touched.

moreover,
the retaining portion has an end wall portion and a cylindrical wall portion extending cylindrically from the end wall portion in the operating direction to define an internal space, the end wall portion is provided with a through hole through which the shaft portion of the spring pressure adjusting member passes, and the engaging portion of the spring pressure adjusting member is engaged with an outer surface of the end wall portion,
The shaft portion of the spring pressure adjusting member may extend in the operating direction through the internal space, and the pressure spring and the buffer spring may be at least partially housed within the internal space.

moreover,
An opening is provided in the cylindrical wall portion, and the spring base has a central portion in which the female thread portion is formed and a rotation inhibiting portion extending from the central portion into the opening, and the rotation inhibiting portion engages with the inner surface of the opening, thereby limiting rotation of the spring base relative to the holding portion.

Furthermore, the device may be provided with a cylindrical guide portion that is fixed to the second mounting member and slidably receives a portion of the cylindrical wall portion to guide the cylindrical wall portion along the operating direction.

Furthermore, a linear guide may be provided between the first mounting member and the second mounting member to guide the first mounting member and the second mounting member so that they are displaced along the operating direction.

In this case, it is possible to provide only one buffer mechanism and one linear guide.

The second mounting member can be displaced from the initial position to the operating limit position by being displaced toward the first mounting member, and the linear guide can prevent the second mounting member from being displaced beyond the initial position in a direction away from the first mounting member.

Alternatively, the second mounting member can be displaced from the initial position to the operating limit position by being displaced away from the first mounting member, and the linear guide can be configured to prevent the second mounting member from being displaced beyond the operating limit position in a direction away from the first mounting member.

Below, an embodiment of the damper according to the present invention will be described with reference to the attached drawings.

1 is a perspective view showing a state in which a damper according to an embodiment of the present invention is attached between an electric screwdriver and a robot arm. FIG. 1 is a perspective view of a damper according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view of the damper of FIG. 2 in an initial position. FIG. 3 is a cross-sectional view of the damper of FIG. 2 at an operating limit position. 11 is a cross-sectional view showing a state in which the spring pressure of the buffer spring is increased by adjusting the spring pressure using a spring pressure adjusting member. FIG. FIG. 11 is a cross-sectional view of a damper according to a second embodiment of the present invention in an initial position. FIG. 7 is a cross-sectional view of the damper of FIG. 6 at its operating limit position.

As shown in FIG. 1, the damper 10 according to the first embodiment of the present invention is used to mount an electric screwdriver (power tool) 1 on a robot arm (automatic machine) 2, and is attached between the electric screwdriver 1 and the robot arm 2.

As shown in FIG. 2, the damper 10 includes a first upper mounting member 12 attached to the robot arm 2, a second lower mounting member 14 attached to the electric screwdriver 1, and a buffer mechanism 16 and a linear guide 18 disposed between the first mounting member 12 and the second mounting member 14. The electric screwdriver 1 is attached to the second mounting member 14 with its tip passing through a tool mounting hole 20 in the second mounting member 14 and its main body passing through a recess 22 in the first mounting member 12. As described later, the second mounting member 14 is guided by the linear guide 18 and can be displaced relative to the first mounting member 12 in the guide direction (operation direction) A of the linear guide 18, and the buffer mechanism 16 operates in response to the displacement, providing a buffer effect.

As shown in FIG. 3, the buffer mechanism 16 includes a cylindrical retaining portion 24 fixed to the first mounting member 12 and a spring pressure adjusting member 26 held by the retaining portion 24. The retaining portion 24 is made of an upper end wall portion 28 and a cylindrical wall portion 32 extending cylindrically downward from the end wall portion 28 in the operating direction A to define an internal space 30, and is fixed to the first mounting member 12 by pressing the cylindrical wall portion 32 into a mounting hole 34 formed in the first mounting member 12. The end wall portion 28 is provided with a through hole 36. The spring pressure adjusting member 26 is a bolt consisting of a head portion 38 and a shaft portion 40 extending downward from the head portion 38 through the through hole 36, and a male thread portion 42 is formed on the outer circumferential surface of the shaft portion 40. The spring pressure adjusting member 26 is arranged so that the direction of the longitudinal axis L of the shaft portion 40 is the same as the operating direction A, and is rotatable around the longitudinal axis L with respect to the retaining portion 24. The buffer mechanism 16 further includes a spring base 44 screwed to the male threaded portion 42 of the shaft portion 40 of the spring pressure adjusting member 26. The spring base 44 has a central portion 48 having a female threaded portion 46 screwed to the male threaded portion 42, and a rotation inhibiting portion 50 extending outward from the central portion 48 toward opposite sides. An opening 52 is formed in the cylindrical wall portion 32 of the holding portion 24, and the rotation inhibiting portion 50 of the spring base 44 extends into the opening 52. The rotation inhibiting portion 50 is adapted to engage with the inner peripheral surface of the opening 52 in the rotation direction, thereby restricting the rotation of the spring base 44 relative to the holding portion 24. The buffer mechanism 16 further includes a buffer spring 54 set between the spring base 44 and the second mounting member 14, and a pressure spring 56 set between the spring base 44 and the end wall portion 28 of the holding portion 24. The pressure spring 56 has a stronger biasing force than the buffer spring 54. A part of the buffer spring 54 and the pressure spring 56 are each arranged around the shaft portion 40 of the spring pressure adjustment member 26 and housed in the internal space 30. The biasing force of the pressure spring 56 causes the engagement portion 58 on the underside of the head portion 38 to be pressed against the outer surface 60 of the holding portion 24, so that the spring pressure adjustment member 26 is not displaced in the direction of the longitudinal axis L relative to the holding portion 24.

The linear guide 18 has a cylindrical member 62 fixed to the first mounting member 12, a guide shaft 64 fixed to the second mounting member 14, and a sliding mechanism 66 arranged between the cylindrical member 62 and the guide shaft 64. The cylindrical member 62 is fixed by being pressed into a mounting hole 68 formed in the first mounting member 12. The guide shaft 64 is fixed to the second mounting member 14 by a mounting nut 72 screwed onto a threaded portion 70 at its lower end. The linear guide 18 in this embodiment is a ball guide in which a number of balls (not shown) are arranged in the sliding mechanism 66, but other forms of linear guides may also be used. This linear guide 18 allows the first mounting member 12 and the second mounting member 14 to linearly displace in the operating direction A while maintaining a parallel state with each other. A displacement limiting nut 74 attached to the upper end of the guide shaft 64 prevents the cylindrical member 62 and the sliding mechanism 66 from displacing any further upward from the position shown in FIG. 3.

The damper 10 further has two cylindrical guides 80, 82 that are press-fitted and fixed into the fixing recesses 76, 78 of the second mounting member 14, respectively. One of the cylindrical guides 80 slidably receives the lower end portion of the cylindrical wall 32 of the holding portion 24 to guide the cylindrical wall 32 along the operating direction A, and prevents the first mounting member 12 from rotating around the linear guide 18.

When the robot arm 2 is operated so that the electric screwdriver 1 is pressed against the workpiece to screw the screw into the workpiece, the second mounting member 14 can be displaced from the initial position in FIG. 3 to the operating limit position in FIG. 4 so as to approach the first mounting member 12. When the second mounting member 14 is displaced toward the operating limit position, the buffer spring 54 is further compressed to urge the second mounting member 14 toward the initial position. On the other hand, the pressing spring 56, which has a stronger urging force, is not compressed regardless of the position of the second mounting member 14. Therefore, the spring base 44 and the spring pressure adjustment member 26 are not displaced relative to the holding portion 24 in the direction of the longitudinal axis L, and the state in which the engagement portion 58 of the spring pressure adjustment member 26 is pressed against the end wall portion 28 of the holding portion 24 is maintained. At the operating limit position in FIG. 4, the two cylindrical guides 80, 82 are in contact with the lower surface 84 of the first mounting member 12, preventing the first mounting member 12 and the second mounting member 14 from moving closer to each other beyond the operating limit position. When the electric screwdriver 1 is removed from the workpiece, the second mounting member 14 returns to the initial position in FIG. 3 due to the biasing force of the buffer spring 54. As described above, the displacement limiting nut 74 of the linear guide 18 limits the displacement of the cylindrical member 62 and the sliding mechanism 66, so the second mounting member 14 does not move further away from the first mounting member 12 beyond the initial position in FIG. 3.

As described above, the spring pressure adjusting member 26 can rotate around the longitudinal axis L relative to the holding portion 24, but is not displaced in the direction of the longitudinal axis L due to the biasing force of the pressure spring 56. When the spring pressure adjusting member 26 is rotated, the spring base 44 screwed to the shaft portion 40 is displaced in the direction of the longitudinal axis L. At this time, the spring base 44 does not rotate relative to the holding portion 24 because its rotation suppressing portion 50 engages with the inner peripheral surface of the opening 52 of the cylindrical wall portion 32. When the spring base 44 is displaced from the upper position in FIG. 3 to the lower position in FIG. 5, the buffer spring 54 is further compressed and its biasing force increases. This increases the spring pressure of the buffer mechanism portion 16. In this way, the spring pressure of the buffer mechanism portion 16 can be easily adjusted simply by rotating the spring pressure adjusting member 26.

The initial position and the operating limit position of the second mounting member 14 are determined by the linear guide 18 and the cylindrical guide portions 80, 82, respectively, as described above, and the range in which the second mounting member 14 can be displaced does not change even if the spring base 44 is moved to adjust the spring pressure of the buffer spring 54. Note that, when the spring base 44 is displaced downward, the pressure spring 56 expands and its biasing force decreases, but within the range in which the spring base 44 can be displaced, the biasing force of the pressure spring 56 is always greater than the biasing force of the buffer spring 54. Therefore, the spring pressure adjustment member 26 is not displaced in the direction of the longitudinal axis L relative to the holding portion 24 by the biasing force of the buffer spring 54, and the state in which the engagement portion 58 is pressed against the end wall portion 28 is always maintained.

Normally, when the coil spring expands and contracts, the end of the coil spring is displaced in the rotational direction, even if only slightly, so that a force in the rotational direction is applied to the member pressing the end of the coil spring. In the damper 10, the spring base 44 pressing the end of the coil-shaped buffer spring 54 is arranged not to rotate with respect to the holding part 24, so it will not rotate even if it receives a force in the rotational direction from the buffer spring 54. The spring pressure adjustment member 26 engages with the buffer spring 54 via the spring base 44 that does not rotate, and does not substantially receive a force in the rotational direction from the buffer spring 54, so it will not rotate due to the action of the buffer spring 54 during operation. Furthermore, the spring pressure adjustment member 26 maintains a state in which the engagement part 58 is pressed against the end wall part 28 by the pressure spring 56, so that a frictional force is always generated between the engagement part 58 and the end wall part 28. The spring pressure adjustment member 26 is also prevented from rotating by this frictional force. This more reliably prevents the spring pressure adjustment member 26 from unintentionally rotating and changing the spring pressure when subjected to vibrations during operation or when the spring pressure adjustment member 26 is accidentally touched.

6 and 7 show a damper 110 according to a second embodiment of the present invention. Here, the configurations different from the damper 10 according to the first embodiment are described, and the description of the similar configurations is omitted. In the damper 110 according to the second embodiment, the first mounting member 112 attached to the robot arm 2 is located on the lower side, and the second mounting member 114 attached to the electric screwdriver 1 is located on the upper side. The holding portion 124 of the buffer mechanism portion 116 extends to the first mounting member 112 through the non-annular through hole 186 of the second mounting member 114 and is fixed to the first mounting member 112. Specifically, the holding portion 124 is pressed into or bonded to the cylindrical stop member 180 that is pressed into and fixed in the fixing recess 176 of the first mounting member 112, and is fixed to the first mounting member 112 via the cylindrical stop member 180. The non-annular through hole 186 has a cross section that is C-shaped or has a shape consisting of a plurality of arcs arranged at intervals, and the outer and inner parts of the non-annular through hole 186 of the second mounting member 114 are connected to each other. The cylindrical wall portion 132 of the holding portion 124 is also shaped to correspond to the non-annular through hole 186. The second mounting member 114 is biased in a direction approaching the first mounting member 112 by a buffer spring 154 set between the spring base 144 and the first mounting member 112. The second mounting member 114 biased by the buffer spring 154 abuts against the cylindrical stop member 180 and the cylindrical guide member 182 and is held in the initial position (FIG. 6). When the robot arm 2 is operated to press the electric screwdriver 1 against the workpiece to screw the screw into the workpiece, the second mounting member 114 can be displaced from the initial position in FIG. 6 to the operating limit position in FIG. 7 away from the first mounting member 112. When the second mounting member 114 is displaced toward the operating limit position, the buffer spring 154 is further compressed to bias the second mounting member 114 toward the initial position. On the other hand, the pressing spring 156, which has a stronger biasing force, is not compressed regardless of the position of the second mounting member 114. Therefore, the spring base 144 and the spring pressure adjusting member 126 are not displaced relative to the holding portion 124 in the direction of the longitudinal axis L, and the state in which the engaging portion 158 of the spring pressure adjusting member 126 is pressed against the end wall portion 128 of the holding portion 124 is maintained. At the operating limit position in FIG. 7, the displacement limit nut 174 of the linear guide 118 limits further displacement of the cylindrical member 162 and the sliding mechanism 166, so that the second mounting member 114 does not move beyond the operating limit position and away from the first mounting member 112. In the damper 110, the cylindrical wall portion 132 of the retaining portion 124 is directly engaged with the non-annular through hole 186 of the second mounting member 114, but it is also possible to fix a cylindrical guide portion to the second mounting member 114 and have the cylindrical guide portion slidably receive the cylindrical wall portion 132 and guide it along the operating direction.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, an automatic machine such as a robot arm can be attached to the second mounting member, and a power tool such as an electric screwdriver can be attached to the first mounting member. In addition, the pressing spring is not necessarily required, and for example, the holding part can press the head of the spring pressure adjustment member from above, so that the head is pressed against the holding part by the biasing force of the buffer spring. Two or more buffer mechanism parts may be arranged. In this case, the linear guide can be eliminated, and linear movement in the operating direction can be ensured by multiple buffer mechanism parts. The damper of the present invention can be used in various automatic machines driven by various power sources such as electric motors, hydraulics, and air pressure, in addition to robot arms. It can also be used when attaching other types of power tools such as nut runners and grinders other than electric screwdrivers to automatic machines.

1. Electric screwdriver (power tool)
2. Robot arm (automatic machine)
10 Damper 12 First mounting member 14 Second mounting member 16 Buffer mechanism section 18 Linear guide 20 Tool mounting hole 22 Recess 24 Holding section 26 Spring pressure adjusting member 28 End wall section 30 Internal space 32 Cylindrical wall section 34 Mounting hole 36 Through hole 38 Head section 40 Shaft section 42 Male thread section 44 Spring base 46 Female thread section 48 Central section 50 Rotation suppressing section 52 Opening 54 Buffer spring 56 Pressing spring 58 Engagement section 60 Outer surface 62 Cylindrical member 64 Guide shaft 66 Sliding mechanism section 68 Mounting hole 70 Thread section 72 Mounting nut 74 Displacement limiting nut 76 Fixing recess 78 Fixing recess 80 Cylindrical guide section 82 Cylindrical guide section 84 Lower surface 110 Damper 112 First mounting member 114 Second mounting member 116 Buffer mechanism section 118 Linear guide 124 Holding portion 126 Spring pressure adjusting member 128 End wall portion 132 Cylindrical wall portion 144 Spring seat 154 Buffer spring 156 Pressing spring 158 Engagement portion 162 Cylindrical member 166 Sliding mechanism portion 174 Displacement limiting nut 176 Fixed recess 180 Cylindrical stop member 182 Cylindrical guide member 186 Non-annular through hole A Guide direction, operating direction L Longitudinal axis

Claims (9)

A damper for mounting a power tool on an automated machine, comprising:
a first attachment member adapted to be attached to one of the power tool and the automated machine;
a second attachment member attached to the other of the power tool and the automatic machine, and displaceable from an initial position to an operating limit position relative to the first attachment member in a predetermined operating direction;
a shock absorbing mechanism portion disposed between the first mounting member and the second mounting member;
Equipped with
The buffer mechanism portion is
a holding portion fixedly disposed relative to the first mounting member;
a spring pressure adjusting member having a shaft portion formed with a male screw portion and arranged so as to be rotatable around a longitudinal axis of the shaft portion relative to the holding portion but not displaceable in the direction of the longitudinal axis;
a spring base having a female screw portion screwed into the male screw portion of the spring pressure adjusting member, the spring base being disposed so as to limit rotation relative to the holding portion, and being displaced in the direction of the longitudinal axis relative to the holding portion when the spring pressure adjusting member rotates;
a buffer spring that is set between the spring base and the second mounting member and is compressed when the second mounting member is displaced from the initial position toward the operating limit position to urge the second mounting member toward the initial position;
A damper having the buffer mechanism further includes a pressure spring that is set between the spring base and the holding portion and has a stronger biasing force than the buffer spring;
The spring pressure adjusting member has an engaging portion that engages with the holding portion from the opposite side of the pressure spring in the direction of the longitudinal axis,
2. The damper according to claim 1, wherein the spring pressure adjusting member is prevented from being displaced in the direction of the longitudinal axis by maintaining a state in which the engaging portion is pressed against the holding portion by the biasing force of the pressure spring. the retaining portion has an end wall portion and a cylindrical wall portion extending cylindrically from the end wall portion in the operating direction to define an internal space, the end wall portion is provided with a through hole through which the shaft portion of the spring pressure adjusting member passes, and the engaging portion of the spring pressure adjusting member is engaged with an outer surface of the end wall portion,
3. The damper according to claim 2, wherein the shaft portion of the spring pressure adjusting member extends in the operating direction through the internal space, and the pressure spring and the buffer spring are at least partially contained within the internal space. The damper according to claim 3, wherein an opening is provided in the cylindrical wall portion, the spring base has a central portion in which the female thread portion is formed and a rotation suppressing portion extending from the central portion into the opening, and the rotation suppressing portion engages with the inner peripheral surface of the opening to restrict rotation of the spring base relative to the holding portion. The damper according to claim 3 or 4, further comprising a cylindrical guide portion fixedly disposed relative to the second mounting member and adapted to slidably receive a portion of the cylindrical wall portion and guide the cylindrical wall portion along the operating direction. The damper according to any one of claims 1 to 5, further comprising a linear guide provided between the first mounting member and the second mounting member, which guides the first mounting member and the second mounting member to displace along the operating direction. The damper according to claim 6, which comprises only one of the buffer mechanism and the linear guide. The damper according to claim 6 or 7, wherein the second mounting member is displaced from the initial position to the operating limit position by displacing it toward the first mounting member, and the linear guide prevents the second mounting member from displacing beyond the initial position in a direction away from the first mounting member. The damper according to claim 6 or 7, wherein the second mounting member is displaced from the initial position to the operating limit position by being displaced away from the first mounting member, and the linear guide prevents the second mounting member from being displaced beyond the operating limit position in a direction away from the first mounting member.

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