KR101639782B1 - Apparatus for dressing grinding wheels - Google Patents

Abstract

The present invention relates to a dressing apparatus for a grinding wheel, and more specifically, to a dressing apparatus for a grinding wheel which uses a single apparatus capable of driving in directions of three axes to machine a grinding wheel used for processing a surface of an object to be processed into various shapes. According to the present invention, the dressing apparatus for a grinding wheel comprises: a fixing unit fixed and installed on a grinder; a main body connected and installed on the fixing unit; a first drive unit connected and installed on the main body to move the main body in a direction perpendicular to a drive shaft of a grinding wheel; a slide member movably slid and mounted on one side of the main body; a second drive unit connected and installed on the slide member to move the slide member in a direction in parallel with the drive shaft of the grinding wheel; a dresser unit connected and installed on the slide member and provided with a dresser for machining the grinding wheel; and a third drive unit connected and installed on the dresser unit to rotate the dresser unit to adjust a contact angle between an outer surface of the grinding wheel and the dresser.

Description

[0001] Apparatus for dressing grinding wheels [0002]

The present invention relates to a dressing apparatus for an abrasive wheel, and more particularly, to a dressing apparatus for an abrasive wheel which is capable of precisely machining a polishing wheel used for surface machining of a workpiece in various shapes using one device capable of driving in three axial directions To a dressing apparatus for an abrasive wheel.

Generally, a grinding machine refers to a machine that rapidly grinds a grinding wheel made of a grindstone or the like to cut or gently grind the surface of a workpiece. The grinding tool is concave, convex, inclined at a predetermined angle depending on the surface shape of the workpiece And a grinding wheel having various types of grinding surfaces.

As described above, when the workpiece is processed by using the abrasive wheel that has been processed into various shapes according to the application, the abrasive wheel is worn and the shape of the periphery of the abrasive wheel is deformed. It is the dressing device which is used for rework of such a grinding wheel.

The dressing apparatus is generally used by being fixedly attached to a bed of a polishing machine. The dressing apparatus includes a diamond tip mounted on a guide block of a predetermined shape to move the diamond tip forward and backward while rotating the polishing wheel, In one embodiment, a polishing wheel dressing apparatus is disclosed in Korean Patent Laid-Open No. 10-2002-0023199.

The main technical feature of the prior art is that a rotary arm is mounted on an end portion of a slide bar which is slid in a direction parallel to the diameter direction of the grinding wheel, and a bite is slidably mounted on the rotary arm, So that various types of polishing wheels can be machined by one dressing device so as to be able to move in various forms.

However, according to the prior art, the operator is configured to manually adjust the slide bar, the rotary arm, and the bite according to the shape of the grinding surface of the grinding wheel. Such an adjustment operation may not be completed at one time, Therefore, in the case of a relatively complicated shape of the polishing surface, it is impossible to perform the machining itself or it is difficult to precisely process the machined surface.

That is, since the rotating radius of the rotating stone is large, the conventional art has a disadvantage that the shape of the polishing surface of the abrasive wheel can not be processed such that a curved line and a curved line intersect with each other or a curved surface having a large radius R .

Therefore, it is convenient to provide a dressing wheel having a machining surface of the same shape as the shape of the polishing surface of the polishing wheel in order to dress the polishing wheel having the polishing surface with various angles and curvatures. In this case, There is a problem in that preparation is very expensive depending on the shape of each grinding wheel.

In addition, the conventional dressing devices are capable of driving in a linear direction or only in a curved direction with a large radius of rotation, which can cause machining errors due to uneven shape of the diamond tip.

1. Korean Patent Publication No. 10-2002-0023199 (published on Mar. 28, 2002) 2. Korean Registered Patent No. 10-1374270 (issued on March 25, 2014)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method and apparatus for driving three axes, that is, linear driving in two axes and rotational driving The present invention provides a dressing apparatus for an abrasive wheel capable of processing a polishing wheel used for surface machining of a workpiece in various shapes using an apparatus.

It is another object of the present invention to provide a dressing apparatus for an abrasive wheel capable of precisely and accurately machining an abrasive wheel having a complicated shape of a polishing surface by electronically controlling driving in three axial directions.

Another object of the present invention is to provide a dressing apparatus for an abrasive wheel which can eliminate a machining error due to a shape imbalance of a diamond tip by adjusting the contact angle between the dresser and the surface of the abrasive wheel by rotation of the dresser. have.

According to an aspect of the present invention,

A dressing apparatus for an abrasive wheel, comprising: a fixed portion fixedly attached to a polishing machine; a main body connected to the fixed portion; a first driving portion connected to the main body to move the main body in a direction perpendicular to the driving shaft of the polishing wheel; A second driving unit connected to the slide member to move the slide member in a direction parallel to the driving shaft of the grinding wheel, and a second driving unit connected to the slide member, And a third driving part connected to the dresser part and rotating the dresser part so as to adjust the contact angle between the outer surface of the polishing wheel and the dresser, .

The fixing unit includes a fixing bracket fixed to the polishing machine, and a connection member connected between the fixing bracket and the main body.

The main body portion is composed of a vertical portion formed in a direction perpendicular to the driving shaft of the grinding wheel and a horizontal portion formed in a direction parallel to the driving shaft of the grinding wheel, The first guide rail and the second guide rail are provided.

The first driving unit includes a first driving motor connected to the main body, a first driving shaft connected to the motor shaft of the first driving motor and having a first male screw formed on an outer circumferential surface thereof, And a first engaging member having a first through hole formed therein with a first female screw fastened to the first male screw.

The second driving unit includes a second driving motor connected to the main body unit, a second driving shaft connected to the motor shaft of the second driving motor and having a second male screw formed on the outer circumferential surface thereof, And a second engagement member having a second through-hole formed therein with a second screw coupled to the second male screw.

The dresser unit includes a housing coupled to the outside of the slide member, a rotating shaft connected to the third driving unit to be positioned inside the housing, and a dresser holder connected to the rotating shaft and coupled to the dresser at an end thereof .

In this case, a support frame for supporting the rotation shaft so as to be rotatable is provided on the outer circumferential surface of the rotation shaft, and a slide block movable in a horizontal direction to the drive shaft of the grinding wheel is connected between the support frame and the dresser holder.

Further, the dresser holder is connected to the slide block so as to be movable in a direction perpendicular to the driving shaft of the polishing wheel.

The support frame is connected to a first stopper for restricting movement of the slide block and a second stopper for restricting movement of the dresser holder.

The third driving unit may include a third driving motor connected to the housing, a driving gear coupled to the motor shaft of the third driving motor, and a driven gear that is engaged with the driving gear and axially installed on the rotating shaft .

The dresser is provided with a scope for visually confirming the rotational center of the dresser by driving the third driving part.

The apparatus may further include a controller for electronically controlling driving of the dresser by the first to third driving units.

According to the present invention, by using a single device capable of linear driving in the biaxial direction and rotational driving around one axis, it is possible to process the grinding wheel used for the surface machining of the workpiece into various shapes .

In addition, according to the present invention, it is possible to electronically control the driving in the three-axis directions, thereby making it possible to precisely and precisely process a polishing wheel having a complicated-shaped polishing surface. Further, by rotating the dresser, It is possible to adjust the contact angle so as to minimize the machining error due to the shape imbalance of the diamond tip.

1 and 2 are perspective views showing a dressing apparatus for an abrasive wheel according to the present invention.
3 is a front view of the present invention shown in Fig.
Fig. 4 is an exploded perspective view showing the fixing part and the first driving part of the present invention shown in Fig. 1 in detail. Fig.
FIG. 5 is a partial perspective view showing the slide member and the second drive unit in detail according to the present invention shown in FIG. 1; FIG.
FIG. 6 is an exploded perspective view illustrating the draWer part and the third driving part of FIG. 1 in detail. FIG.
FIG. 7 is an exploded perspective view showing another embodiment of the present invention shown in FIG. 6; FIG.

Hereinafter, preferred embodiments of a dressing apparatus for an abrasive wheel according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a front view of the present invention shown in FIG. 2, and FIG. 4 is a cross-sectional view of a dressing apparatus for an abrasive wheel according to the present invention, FIG. 5 is a partial perspective view showing in detail the slide member and the second driving unit according to the present invention shown in FIG. 1, and FIG. 6 is a perspective view showing in detail the drainer unit and the third driving unit And FIG. 7 is an exploded perspective view showing another embodiment of the present invention shown in FIG.

The present invention relates to an abrasive wheel (10) used for surface machining of a workpiece using a single device capable of driving in three axial directions, that is, linear driving in two axial directions and rotational driving around one axis, (Hereinafter, referred to as "dressing apparatus 100") that can be accurately machined to a desired shape, as shown in FIGS. 1 and 2. The main components of the dressing apparatus 100 are a fixed portion 110 A main body 120, a first driving part 130, a slide member 140, a second driving part 150, a drape part 160, and a third driving part 170.

More specifically, the fixing unit 110 serves to fix the dressing apparatus 100 according to the present invention to the polishing machine. The fixing unit 110 includes a fixing bracket 112 and a connecting member 114, do.

That is, the fixing bracket 112 is coupled to a polishing machine (not shown) by fastening means such as a bolt, so that the dressing apparatus 100 can be fixed to the polishing machine. And is fixed on the horizontal portion 124 of the body portion 120 to be described later.

The connecting member 114 is connected between the fixing bracket 112 and the main body 120 so that the fixing bracket 112 can be fixed to the main body 120, A guide groove 114a is formed at a lower portion of the member 114 to be coupled to the first guide rail 122a of the main body 120, which will be described later.

The main body 120 serves as a main body to which the first to third driving units 130, 150 and 170 for driving the dresser 168 for machining the polishing wheel 10 are connected. Respectively.

More specifically, the main body 120 includes a vertical part 122 extending in a direction perpendicular to the driving shaft 20 to which the polishing wheel 10 is coupled (hereinafter, referred to as an 'x-axis direction'), And a horizontal part 124 extending in a horizontal direction (hereinafter, referred to as' y-axis direction ') with respect to the driving shaft 20. The vertical part 122 is formed in a shape of' The first driving unit 130 is connected to move the fixing unit 110 and the dresser 168 in the direction perpendicular to the driving shaft 20 of the polishing wheel 10, that is, in the x axis direction, The horizontal part 124 is provided with a slide member 140 and a slide member 140 for moving the dresser 168 in a direction horizontal to the drive shaft 20 of the grinding wheel 10, The second driving unit 150 is connected to the second driving unit.

That is, the vertical part 122 of the main body part 120 is provided with the first guide rail 122a so that the main body part 120 is guided by the first guide rail 122a by driving the first driving part 130, And the second guide rail 124a is provided on the horizontal portion 124 to move the slide member 140 and the dre The western portion 160 can move in the y-axis direction along the second guide rail 124a.

The first driving part 130 is connected to the vertical part 122 of the main body part 120 to connect the main body part 120 and the dresser 168 for machining the polishing wheel 10 connected to the body part 120, And includes a first drive motor 132, a first drive shaft 134, and a first engagement member 136, as shown in FIG.

More specifically, the first driving motor 132 is connected to the vertical portion 122 of the main body 120 to generate a driving force for rotating the main body 120, that is, The first driving shaft 134 is connected to the motor shaft of the first driving motor 132 and transmits the rotational force generated from the first driving motor 132.

The first driving shaft 134 is installed in the longitudinal direction of the vertical portion 122, that is, the x-axis direction. The first driving shaft 134 has a first male screw 134a formed on the outer circumferential surface thereof, And the body portion 120 can be moved by the engagement with the member 136. [ As the second driving shaft 154 of the first driving shaft 134 and the second driving unit 150 to be described later, a normal ball screw may be used.

The first engaging member 136 is connected between the connecting member 114 of the fixing unit 110 and the first driving shaft 134 and is driven by the first driving motor 132, A first through hole 136a through which the first driving shaft 134 is inserted is formed in the inner side of the first engaging member 136, that is, the center portion thereof, The first through-hole 136a is formed with a first female thread to be engaged with the first male thread 134a.

That is, when the first driving shaft 134 rotates by the driving of the first driving motor 132, the first engaging member 136 coupled to the first driving shaft 134 is coupled to the fixing unit 110 The first drive shaft 134 moves along the x-axis direction and the first drive shaft 134 moves to the main body part 120 and the main body part 120, The connected dresser 168 is moved in the x-axis direction.

The slide member 140 is configured to slide along one side of the main body 120, that is, on the outer side of the horizontal portion 124 and to move along the longitudinal direction of the horizontal portion 124, that is, along the y-axis direction The dresser 168 connected to the slide member 140 can move in the y-axis direction.

At this time, the slide member 140 is formed with a guide groove 142 to be coupled to the second guide rail 124a provided at the horizontal portion 124, so that the slide member 140 140 can move in the y-axis direction along the second guide rail 124a.

The second driving unit 150 is connected to the slide member 140 to move the slide member 140 in the y-axis direction. As shown in FIG. 5, A first driving shaft 152, a second driving shaft 154, and a second engaging member 156.

That is, the second driving motor 152 is connected to the horizontal portion 124 of the main body 120 to generate a driving force, that is, a rotational force for moving the slide member 140, The second driving shaft 154 is connected to the motor shaft of the second driving motor 152 to transmit the rotational force generated from the second driving motor 152, And is connected between the member 140 and the second drive shaft 154 so that the slide member 140 can be moved by the driving of the second drive motor 152.

A second male screw 154a is formed on the outer circumferential surface of the second driving shaft 154 and a second through hole 156 is formed in the inner side of the second engaging member 156, And the second through hole 154a is formed in the second through hole 156a. The detailed operation of the first and second through holes 156a and 154b is determined by the operating relationship of the first driver 130 The detailed description thereof will be omitted.

Next, the dresser unit 160 is connected to the slide member 140 to move the driving force of the main body 120 and the slide member 140 by the driving of the first and second driving units 130 and 150, The rotating shaft 164, the dresser holder 166, and the dresser 168, as shown in Fig. 6, .

More specifically, the housing 162 serves to fix the dreading portion 160 to the slide member 140, and is fixed to the outer side of the slide member 140 by fastening means such as a bolt or the like. Respectively.

The rotating shaft 164 is connected to the dresser holder 166 by the third driving part 170 so as to be positioned inside the housing 162. The rotating shaft 164 is rotated by the driving of the third driving part 170 And serves to rotate the dresser 168 coupled to the dresser holder 166 by rotating the dresser holder 166.

That is, in general, if the shape of the diamond tip used as the dresser 168 is not a precise spherical or " 형상 " shape, the unbalanced shape of the diamond tip causes the machining of the abrasive wheel 10 to have an accurate shape The machining error due to the shape of the diamond tip can be minimized by adjusting the contact angle between the dresser 168 and the polishing wheel 10 by rotating the rotary shaft 164 according to the shape of the diamond tip.

More specifically, when the shape of the diamond tip is asymmetrical, the contact angle between the dresser 168 and the polishing wheel 10 is adjusted by the rotation of the rotating shaft 164, thereby adjusting the center of curvature formed by the diamond tip, It is possible to minimize the machining error of the polishing wheel 10 due to the asymmetrical shape of the diamond tip by making the virtual line connecting the contact portion of the wheel 10 perpendicular to the outer surface of the polishing wheel 10. [

Next, the dresser holder 166 serves to fix the dresser 168 for machining the polishing wheel 10, and is connected to the rotating shaft 164.

The dresser holder 166 is connected between the rotating shaft 164 and the dresser 168 to fix the dresser 168 and to rotate the dresser 168 and the grinding wheel 10 And the contact angle between the contact surface and the contact surface is controlled.

Next, the dresser 168 functions to process the outer surface of the grinding wheel 10. The position of the dresser 168 and the contact angle with the grinding wheel 10 are adjusted by driving the first to third driving parts 130, . ≪ / RTI >

A support frame 165 may be coupled to the outer peripheral surface of the lower end of the rotary shaft 164 so that the support frame 165 is coupled to the outer side of the housing 162 to rotate the rotary shaft 164 in the housing 162, respectively.

In this case, bearings for smooth rotation of the rotary shaft 164 may be inserted between the support frame 165 and the rotary shaft 164.

6, a slide block 167 is connected between the support frame 165 and the dresser holder 166. The slide block 167 is manually connected to the dresser holder 166 by manual operation, And to move the dresser 168 coupled thereto in the y-axis direction.

That is, a dovetail-shaped first engaging portion 167a is protruded in the y-axis direction on the upper portion of the slide block 167, and the lower end of the support frame 165 corresponds to the shape of the first engaging portion 167a And the slide block 167 is coupled to the support frame 165 so as to be movable in the y-axis direction.

A second engaging portion 166a of a dovetail shape is protruded from the upper portion of the dresser holder 166 in the x-axis direction and a lower portion of the slide block 167, to which the dresser holder 166 is engaged, And a second engaging groove 167b corresponding to the shape of the part 166a is formed so that the dresser holder 166 and the dresser 168 coupled thereto can be moved in the x axis direction by manual operation.

That is, at the time of processing the polishing wheel 10 having a simple shape like a planar shape, the dresser holder 166 or the slide block 167 can be manually operated without operating the first to third driving portions 130, So that the dresser 168 can be moved in the x-axis direction or the y-axis direction to machine the surface of the polishing wheel 10.

The first stopper 165b and the second stopper 165c may be connected to the support frame 165. The first stopper 165b may be connected to both ends of the support frame 165 in the y- And the second stopper 165c is connected to both ends of the support frame 165 in the x-axis direction so as to limit the movement of the slide block 167 in the x direction of the dresser holder 166. [ Thereby restricting axial movement.

In the present invention, a dresser 168 using a single diamond tip, which is generally known as a point dresser, has been described. However, as shown in FIG. 7, a dresser holder 166 may be removed and a dresser holder 166 'equipped with a roll dresser 168' equipped with a plurality of diamond tips may be connected and used.

In other words, since the wear of the diamond tip is less likely to occur when a plurality of diamond tips are used than one diamond tip, the position of the point dresser 168 and the roll dresser 168 'can be changed by replacing the dresser holder 166, 166' ) Can be selectively used.

At this time, a motor 169 'for rotating the roll dresser 168' is installed in the dresser holder 166 '.

The third driving part 170 is connected to the dresser 160 to rotate the rotating shaft 164 of the dresser 160 so that the contact angle between the outer surface of the polishing wheel 10 and the dresser 168 And includes a third drive motor 172, a drive gear 174, and a driven gear 176.

The third drive motor 172 generates a rotational force for rotating the rotation shaft 164 and the drive gear 174 is connected to the motor shaft 172 of the third drive motor 172. [ And transmits the rotational force of the third drive motor 172 to the driven gear 176. [

The driven gear 176 meshes with the driving gear 174 and is axially supported on the rotating shaft 164 so that the rotating shaft 164 is rotated by the rotational force of the third driving motor 172 transmitted by the driving gear 174. [ So that it can be rotated.

The action and effect of the rotation of the rotating shaft 164, which is generated by the driving of the third driving unit 170, is as described above, and thus a detailed description thereof will be omitted.

1 and 2, the scope 180 may be provided on the dresser unit 160. The scope 180 may be mounted on the dresser unit 160 by driving the third drive unit 170, That is, the center of rotation of the dresser 168 can be visually confirmed.

The scope 180 can visually confirm the center of rotation of the dresser 168 so that the distance between the outer surface of the polishing wheel 10 and the dresser 168 according to the shape of the diamond tip used as the dresser 168 So that it is possible to minimize the machining error.

The dressing apparatus 100 according to the present invention may further include a control unit (not shown) for controlling the driving of the first to third driving units 130, 150 and 170, that is, the first to third driving motors 132 and 152.172 The controller controls the movement of the dresser 168 in the x-axis direction and the y-axis direction by the driving of the first to third driving units 130, 150 and 170 and the rotation angle about the rotation axis 164 electronically, So that the driving of the apparatus 100 can be performed automatically.

That is, when the user inputs the movement distance and the rotation angle in the x-axis direction and the y-axis direction of the dresser 168 using the input means (not shown), the control unit receives the movement distance and the rotation angle and outputs them to the first to third drive motors 132, The grinding wheel 10 having a complicated surface shape can be accurately machined.

Therefore, according to the dressing apparatus 100 for an abrasive wheel according to the present invention, as described above, it is possible to use a single apparatus capable of linear driving in the biaxial direction and rotational driving around one axis The grinding wheel 10 having a complicated shape can be precisely and precisely machined by allowing the grinding wheel 10 to be processed in various shapes and electronically controlling the driving in the three axis directions It is possible to control the contact angle between the dresser 168 and the surface of the polishing wheel 10 by the rotation of the dresser 168 so that the machining error due to the shape imbalance of the diamond tip can be minimized will be.

Although the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit of the invention.

The present invention relates to a dressing apparatus for an abrasive wheel, and more particularly, to a dressing apparatus for an abrasive wheel which is capable of precisely machining a polishing wheel used for surface machining of a workpiece in various shapes using one device capable of driving in three axial directions To a dressing apparatus for an abrasive wheel.

100: dressing device 110:
112: fixing bracket 114: connecting member
114a, 142: guide groove 120:
122: vertical part 122a: first guide rail
124: horizontal portion 124a: second guide rail
130: first driving part 132: first driving motor
134: first driving shaft 134a: first male screw
136: first engagement member 136a: first through hole
140: slide member 150: second drive part
152: second drive motor 154: second drive shaft
154a: second male screw 156: second coupling member
156a: second through hole 160:
162: Housing 164:
165: support frame 165a: first engagement groove
165b: first stopper 165c: second stopper
166, 166 ': a dresser holder 166a:
167: Slide block 167a:
167b: second engaging groove 168: (point) dresser
168 ': Roll Dresser 169: Motor
170: third driving unit 172: third driving motor
174: driving gear 176: driven gear
180: Scope

Claims (12)

A dressing apparatus for an abrasive wheel,
A stationary bracket fixed to the abrasive machine, and a connecting member connected between the stationary bracket and the main body and having a guide groove at a lower portion thereof;
A vertical part having a first guide rail formed in a direction perpendicular to a drive shaft of the grinding wheel and coupled to the guide groove, and a horizontal part formed in a direction parallel to a driving shaft of the grinding wheel and having a second guide rail, A body portion connected to the fixing portion;
A first driving unit connected to the main body to move the main body in a direction perpendicular to the driving axis of the polishing wheel;
A slide member having a guide groove coupled to the second guide rail and slidably coupled to the horizontal portion of the main body;
A second driving unit connected to the slide member to move the slide member in a direction parallel to the driving shaft of the polishing wheel;
A dresser portion connected to the slide member and including a dresser for working a polishing wheel;
A third driving unit connected to the dresser to rotate the dresser unit so as to adjust the contact angle of the dresser with the outer surface of the polishing wheel;
And a scope provided in the dresser to visually confirm the center of rotation of the dresser by driving the third driving unit,
The dresser includes a housing coupled to an outer side of the slide member, a rotation shaft connected to the third drive unit so as to be positioned inside the housing, a support frame installed on an outer circumferential surface of the rotation shaft to support the rotation shaft rotatably, A dresser holder connected to the rotary shaft and coupled to the dresser at an end thereof, and a slide block connected between the support frame and the dresser holder,
A first engaging portion of a dovetail shape is protruded from the upper portion of the slide block. A first engaging groove corresponding to the shape of the first engaging portion is formed at a lower portion of the supporting frame. And is configured to be movable,
And a second engaging groove corresponding to the shape of the second engaging portion is formed at a lower portion of the slide block to which the dresser holder is coupled so that the dresser holder is abraded to the slide block And is connected to be movable in a direction perpendicular to the drive shaft of the wheel,
Wherein a first stopper for restricting movement of the slide block and a second stopper for restricting movement of the dresser holder are connected to the support frame.
delete delete The method according to claim 1,
A first driving shaft connected to the motor shaft of the first driving motor and having a first male screw on an outer circumferential surface thereof; a first driving shaft connected to the fixing portion, And a first engaging member having a first through hole with a first female thread fastened to the male screw.
The method according to claim 1,
A second drive shaft connected to the motor shaft of the second drive motor and having a second male screw formed on an outer circumferential surface thereof, a second drive shaft connected to the slide member, And a second engaging member having a second through-hole formed therein with a second screw engaged with the male screw.
delete delete delete delete The method according to claim 1,
The third driving unit may include a third driving motor connected to the housing, a driving gear coupled to the motor shaft of the third driving motor, and a driven gear that meshes with the driving gear and is installed in the rotary shaft. A dressing device for an abrasive wheel.
delete The method according to claim 1,
Further comprising a control unit for electronically controlling driving of the dresser by the first to third driving units.

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