JPH10225837A - Correcting head driving device of work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform adjusting work of a correcting head with high accuracy by electromagnetically coupling a tool holder and an electric power supply part with each other, supplying electric power from an external part to a detecting part arranged in this tool holder, on the one hand, and driving the correcting head from an external part after a driving means is joined to a driving force transmitting part. SOLUTION: A slide shaft of a driving means is joined to a driving force transmitting part 34 of a tool holder 18, and adjusting work of a correcting head 22 is performed under the rotary action of this slide shaft. In that case, an adjusting condition of the correcting head 22 is directly detected by a sensor 68 of a detecting part 36 receiving supply of electric power from an external part by electromagnetic coupling. Detecting information of the sensor 68 is sent to a controller by radiocommunication, and a DC mode of a driving means is controlled on driving through this controller. Therefore, correcting work of the correcting head 22 is reliably performed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correction head driving device for a working machine for externally adjusting a correction head of a tool holder mounted on a spindle.

2. Description of the Related Art Usually, in a machining center or the like, an operation of automatically changing various tools by an automatic tool changing mechanism (ATC) is performed. In this type of work, a tool holder having a so-called ATC shank is used, and a configuration in which the tool holder is automatically attached to and detached from a spindle is generally adopted. By the way, there is a demand for detecting the state of a tool attached to the tool holder, for example, the processing state of a cutting tool, and automatically adjusting the position of the cutting tool by a correction mechanism or the like. For this reason,
For example, a push / pull rod is extended from a spindle, connected by a shank portion, and the rod is pressed / pulled, so that a cutting tool mounting cartridge provided in a tool holder is driven through a wedge type or taper type driving means. A structure for moving the spindle in the radial direction is known. In the above structure, specifically, the amount of movement of the rod on the side of the shank connecting portion that is considerably separated from the cartridge is attached to the cartridge on the foremost side of the tool holder via a wedge-type or taper-type driving means. It is converted to a bite displacement.

However, while the correction drive is transmitted from the stepping motor for driving the rod to the cutting tool of the cartridge, various contact parts, sliding parts, minute deformation parts and the like are present. I have. For this reason, it has been pointed out that even if the stepping motor is controlled with high accuracy, it is extremely difficult to accurately control the micron unit in the bite.
The present invention solves this kind of problem, and can directly and accurately detect the adjustment state of a correction head provided on a tool holder, and can perform high-precision correction work with a simple configuration. It is an object of the present invention to provide a correction head driving device for a working machine.

According to the present invention, a tool holder and a power supply unit are electromagnetically coupled to each other, and power is supplied from an external source to a detection unit provided in the tool holder. On the other hand, the driving unit is coupled to the driving force transmitting unit, and the correction head is driven from the outside. Therefore, the adjustment state of the correction head is directly detected via the detection unit, and the driving unit is controlled based on the detection result, so that the adjustment operation of the correction head is performed with high accuracy and efficiency. In addition, a controller that performs wireless communication with the tool holder is provided, and the driving unit is controlled by the controller based on wireless information from the detection unit. This allows
Control of the correction head is more reliably and accurately performed. Furthermore, the drive means includes a rotary coupling portion which engages with the driving force transmission portion and is rotatable under the action of the rotary drive source, and a power supply portion is provided integrally with the rotary coupling portion. For this reason, the driving means and the power supply unit are integrated, so that the configuration is simplified at a stroke and the control is easily performed.

FIG. 1 shows a working machine 12 incorporating a correction head driving device 10 according to a first embodiment of the present invention.
FIG. The working machine 12 includes a machine tool 14, a tool holder 18 that is detachable from a spindle 16 of the machine tool 14, a power supply unit 20 for supplying power to the tool holder 18,
And a controller 26 for driving the correction head 22 provided from the outside from the outside, and a controller 26 capable of wireless communication with the tool holder 18. The correction head driving device 10 according to the present embodiment basically includes a tool holder 1
8 and a power supply unit 2
0 and driving means 24. The spindle 16 is connected to a rotation drive source (not shown) and rotatably supported by the movable base 28, and moves in the direction of arrow A (horizontal direction), the direction of arrow B (vertical direction), and the direction of arrow D (axial direction). It is free. As shown in FIG.
Is a shank part 3 fitted to the spindle 16 at one end.
0, and a bite (tool) 32 is attached to the other end.
The tool holder 18 includes a correction head 22 capable of adjusting the position of the cutting tool 32 in the radial direction (the direction of arrow C) of the spindle 16 and a driving force transmission unit for adjusting the correction head 22 by an external driving force. 34, and a detector 36 for detecting the adjustment state of the correction head 22. The driving force transmission unit 34 includes a drive worm gear 38 rotatably mounted in the tool holder 18. The drive worm gear 38 intersects the axis of the tool holder 18 and is eccentric by a predetermined distance from the center of the tool holder 18. I have. As shown in FIG. 3, a hexagonal hole 40 and a guide hole 42 are formed coaxially in the center of the drive worm gear 38. As shown in FIGS. 2 and 3, the drive worm gear 38 meshes with the worm wheel 44, and the worm wheel 44 extends in the axial direction of the tool holder 18 (direction of arrow D) and is rotatably supported. Is done. Through hole 4 of worm wheel 44
The shaft portion 52 of the conical tapered drive shaft 50 engages with the shaft 6 via a pin 48 and an elongated hole 49 so as to be able to advance and retreat in the axial direction (see FIG. 2). A spring 54 is provided on the shaft portion 52 of the tapered drive shaft 50, and a plurality of rollers 56 have a slight inclination on the outer peripheral surface of the tapered drive shaft 50 and can roll freely through a cage 58. In addition, a power unit 60 is provided outside the roller 56. Power unit 6
In the case of No. 0, a tapered surface 62 corresponding to the outer peripheral surface of the tapered drive shaft 50 is formed on the inner peripheral side, while the outer peripheral surface is set to the same dimension (straight outer periphery) in the axial direction. The power unit 60 is provided with a pair of slits (not shown) from both ends, which are close to each other. When the taper drive shaft 50 is rotated, the taper drive shaft 50 and the roller 56 rotate and rotate. By moving to, it is possible to enlarge or reduce within a predetermined range. A head housing 64 is provided on the outer periphery of the power unit 60. The head housing 64 has a substantially cylindrical shape, and has an S-shaped slit 66 on its outer peripheral surface.
Is formed. When the power unit 60 expands in diameter as described above, the head housing 64 is pushed outward in the diameter and is displaced in the direction of arrow C1 via the S-shaped slit 66. The detecting unit 36 is provided by the arrow C of the head housing 64.
A displacement detection sensor 68 for detecting a corrected displacement in the direction is provided. As shown in FIG. 4, the sensor 68 has a winding coil 72 disposed in a magnetic shield 70, and the measurement core 7 extends along a guide portion 74 on which the winding coil 72 is provided.
6 is free to advance and retreat. The measuring core 76 includes the contact portion 7
8, and the guide portion 74 includes a fixing member 79.
Is screwed to one of the expansion and contraction halves of the power unit 60. The sensor pressing portion 81 is
The contact portion 78 and the sensor pressing portion 81 move in the direction of arrow C integrally with the head housing 64 while always maintaining the pressed state, and are fixed to the other expanding and contracting half of the power unit 60 by screwing. . Contact part 7
8, one end of a bellows capsule 80 is fixed, and the bellows capsule 80 covers the winding coil 72 and the magnetic shield 70. Wound coil 7 of sensor 68
2 is connected to the oscillation modulator 82. The high frequency in the MHZ band is sent from the oscillation modulator 82 to the transmitter 84,
An antenna 86 connected to the transmitter 84 is provided on the outer periphery of the tool holder 18 with a protective body 8 made of a synthetic fiber, a resin material, or the like.
8 and 90 to be mounted (see FIG. 2). The controller 26 includes a receiver 96 that receives an FM wave transmitted as an electromagnetic wave from an antenna 86 of a transmitter 84 from an antenna 94, and the receiver 96 converts the FM wave into a demodulator 98.
To supply. The counting section 100 is connected to the demodulator 98, the frequency counted by the counting section 100 is converted and displayed on the correction amount display 102, and the calculation section 104 calculates the correction displacement of the correction head 22. The controller 26 is provided with a correction instructing unit 106, from which (+) (forward rotation) and (−)
The instruction of (reverse rotation) is input to the arithmetic unit 104. The calculation unit 104 is connected to a DC motor 152 (described later) constituting the driving unit 24 via the input / output device 108.
As shown in FIG. 3, an electromagnetic coupling portion 110 is provided on the outer peripheral portion of the tool holder 18 coaxially with the drive worm gear 38 constituting the driving force transmitting portion 34. Electromagnetic coupling 1
Reference numeral 10 denotes a winding coil 112 for electromagnetic coupling. The winding coil 112 is applied to a first ferromagnetic body 114 such as ferrite directly embedded in the tool holder 18.
The winding coil 112 is connected to a stabilized power supply 117 via a detection rectifier 115 (see FIG. 4). Tool holder 1
The electromagnetic coupling portion 8 of 8 is made of a good electrical conductor such as iron, aluminum, copper or silver. As shown in FIG. 1, the driving unit 24 includes a cylinder (for example, an air cylinder) 116 which is an actuator mounted at a corner of the machine tool 14. As shown in FIG.
6, a spindle portion 118 is rotatably disposed via a bearing 120. A cylinder member 122 of the spindle portion 118 is provided with a sleeve member 126 having a piston portion 124 at one end so as to be able to move up and down. You. The cylinder 116 has first and second ports 128a and 128b communicating with the upper and lower edges of the cylinder chamber 122, and the sleeve member 126 has therein the cylinder chamber 130.
The upper side of the cylinder chamber 130 communicates with the first port 128a via a passage 132. In the cylinder chamber 130, a slide shaft 136 provided with a piston portion 137 at an upper portion is slidably disposed. The lower side of the piston portion 137 communicates with the second port 128b via a passage 134. Although not shown, the slide shaft 136 is supported by a return spring disposed in the cylinder chamber 122 and is constantly urged upward. As shown in FIG. 6, the inner diameter of the sleeve member 126 and the outer diameter of the piston portion 137 have an oval or polygon shape, and similarly, the inner diameter of the spindle portion 118 and the outer diameter of the piston portion 124 have an oval or polygon shape. It has a shape. At the lower end of the slide shaft 136, a hexagon wrench part 138 and a guide part 139 constituting the driving means 24 are provided. Above the hexagon wrench part 138, a coupling head part 140 constituting the power supply part 20 is provided.
Are provided integrally. As shown in FIG. 7, the coupling head portion 140 is provided on the first ferromagnetic material 114 of the tool holder 18.
With the winding coil 142 forming an electromagnetic coupling
Is provided. The winding coil 142 is longer in the axial direction of the coupling head 140 than the winding coil 112, and is connected to a high-frequency oscillator (not shown). The coupling head section 140 is made of a good electrical conductor such as iron, aluminum, copper, or silver, similarly to the electromagnetic coupling section 110. As shown in FIG.
A first gear 146 is fixed to the upper end of the first gear 18.
The second gear 148 meshing with the gear 146 is
Is attached to the DC motor 152 through the shaft. The DC motor 152 is supported by the cylinder 116 via a mounting portion 154 in a vertically downward direction. The operation of the working machine 12 incorporating the correction head driving device 10 according to the first embodiment configured as described above will be described below. The tool holder 18 is mounted on the spindle 16,
Arrow A, arrow B while rotating under the action of the machine tool 14
The workpiece is selectively moved in the direction and the arrow D direction, and a predetermined processing (for example, hole processing) is performed on a work (not shown). And
The diameter of the machined hole is measured, and when the machined hole diameter is not within the tolerance, the cutting tool 32 is corrected. That is, the spindle 16 is transferred to the predetermined standby position and the tool holder 18 is in the ready state until a series of machining is completed and the process shifts to machining of the next work (not shown). Then
As shown in FIG. 5, when air is supplied to the first port 128a of the cylinder 116 that constitutes the power supply unit 20, the sleeve member 126 moves downward (in the direction of the arrow B1) and the passage of the sleeve member 126 The slide shaft 136 is moved downward by the air pressure introduced into the cylinder chamber 130 via the 132 (see FIG. 3). For this reason, as shown in FIG. 7, the hexagon wrench 138 provided at the tip of the slide shaft 136 is
4 is inserted into the hexagonal hole 40 of the drive worm gear 38, or is disposed at a position immediately before the insertion. that time,
The second ferromagnetic body 144 of the coupling head unit 140 is configured to be longer than the first ferromagnetic body 114 of the tool holder 18, and the second ferromagnetic body 144 and the first ferromagnetic body It is possible to reliably position the body 114 and each other. Therefore, if high-frequency oscillation is performed from the power supply unit 20 side, there is an advantage that the first and second coils 112 and 142 are electromagnetically coupled and power is efficiently supplied to the first coil 112 side. In addition, by using high frequency, desired electric energy can be reliably transmitted in a small space. When power is supplied to the tool holder 18 side by the electromagnetic coupling, the sensor 68 is driven as shown in FIG. In the sensor 68, the guide portion 74 is fixed to one of the expansion and contraction halves of the power unit 60, and the sensor pressing portion 81 is fixed to the other expansion and contraction half of the power unit 60, so that the contact portion 78 and the sensor pressing portion 81 are always The pressed state is maintained. When the head housing 64 has been corrected and moved in the direction of arrow C, the measuring core 76 is at the corrected position along the guide portion 74 via the contact portion 78 and the sensor pressing portion 81, and the total conductance of the winding coil 72. Can obtain a high frequency (MHZ) corresponding to the position. This high frequency is wirelessly received by the receiver 96 from the antenna 94 of the controller 26 via the antenna 86 from the transmitter 84 and counted after demodulation, and the displacement of the sensor 68 is detected.
That is, the amount of the correction displacement of the correction head 22 is measured. Here, since the sensor 68 uses high-frequency oscillation, the rate of change increases even with a small number of turns. Therefore, high accuracy can be easily achieved, and the size of the sensor 68 itself can be effectively reduced. In the controller 26, the correction instruction section 10
6 is compared with the correction state of the correction head 22 by the wireless communication from the sensor 68 by the arithmetic unit 104,
In order to rotate the C motor 152 forward or reverse, the operation unit 1
From (04), (+) (forward) and (−) (reverse) instructions are input to the input / output device 108. This input / output device 108
Turns the DC motor 152 forward or reverse. The rotation of the DC motor 152 is, as shown in FIG.
The transmission is transmitted to the second gear 148 at a considerably reduced speed, and the spindle unit 118 rotates integrally with the first gear 146 meshing with the second gear 148. This spindle unit 11
8 and the inner diameter of the sleeve member 126 and the outer diameter of the piston portions 124 and 137 that slidably engage with them have an oval or polygonal shape, and the piston portion 124, the sleeve member 126, and the slide shaft 136 rotates integrally. Accordingly, the hexagon wrench 138 provided at the tip of the slide shaft 136 is
The drive worm gear 38 is inserted into the hexagonal hole 40 of the drive worm gear 38, and the drive worm gear 38 is rotated. The rotation of the drive worm gear 38 is transmitted to the tapered drive shaft 50 via the worm wheel 44 under the action of the pin 48 and the elongated hole 49, and the plurality of rollers 56 slidably contacting the outer peripheral surface of the tapered drive shaft 50 rotate. I do. Thereby, the taper drive shaft 50 and the plurality of rollers 56 roll in the front-rear direction (arrow D direction), and the power unit 60 expands and contracts within a predetermined range (arrow C direction).
Is done. When the power unit 60 expands and contracts in the direction of arrow C, the sensor 68 is driven as described above, and the displacement of the power unit 60, that is, the displacement of the correction head 22, is wirelessly communicated to the controller 26. After the correction of the correction head 22 is completed, air is supplied to the second port 128b of the cylinder 116 constituting the power supply unit 20. This air is introduced to the lower side of the piston part 124 to raise the sleeve member 126 and to cause the passage 13
4 and is introduced into the lower side of the cylinder chamber 130 to raise the slide shaft 136. For this reason, the power supply unit 2
0 and the driving means 24 are separated from the tool holder 18 and arranged at a predetermined standby position. In this case, in the first embodiment, the coupling head 140 of the power supply unit 20 moves close to the electromagnetic coupling unit 110 of the tool holder 18, and the first coil 112 of the electromagnetic coupling unit 110 and the coupling head The second coil 142 of the unit 140 forms electromagnetic coupling. On the other hand, a slide shaft 136 constituting the drive means 24 is coupled to the drive force transmitting portion 34 of the tool holder 18, and the adjustment operation of the correction head 22 is performed under the rotation of the slide shaft 136. At this time, the adjustment state of the correction head 22 is determined by the sensor 68 constituting the detection unit 36 which is supplied with power from the outside by the electromagnetic coupling.
Detected directly. And the detection information of the sensor 68 is
The data is sent to the controller 26 by wireless communication, and the driving of the DC motor 152 constituting the driving unit 24 is controlled via the controller 26. Accordingly, an effect is obtained that the correction operation of the correction head 22 is performed with high accuracy and certainty. Further, the cylinder 11 constituting the driving means 24
No. 6 only requires ON / OFF control of the supply of air to the first and second ports 128a and 128b, and the stroke control of the slide shaft 136 is simplified. For this reason, the control of the driving means 24 is simplified all at once, and the speed of the entire operation is easily achieved. Further, there is no need to store a battery in the tool holder 18, and the tool holder 18 itself can be reduced in size at once, and desired power can be easily and reliably supplied from the power supply unit 20 to the tool holder 18 side. It becomes possible to supply.
If there is a possibility that cutting chips or the like may adhere to the hexagonal hole 40 of the drive worm gear 38, a hole for air blow is formed through the slide shaft 136, and the slide is formed through the hole. The slide shaft 136 can be moved toward the hexagonal hole 40 while performing air blowing from the tip of the shaft 136. FIG.
FIG. 9 is a partial longitudinal sectional view of a driving unit 180 included in a correction head driving device according to a second embodiment of the present invention. Note that the same components as those of the driving unit 24 constituting the correction head driving device 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Driving means 18
0 is the rotating cylinder 18 disposed in the cylinder 116
2, and a hole 183 for air is formed on the side of the rotary cylinder 182. In the upper part of the rotary cylinder 182,
A drive sleeve 184 is rotatably supported. The first gear 146 is fixed to the upper portion of the drive sleeve 184, while the inner slide sleeve 1 is connected to the lower portion of the drive sleeve 184 via the drive steel ball 186.
An upper portion of the support member 88 is integrally rotatably supported. An outer peripheral portion of the inner slide sleeve 188 is formed with a ball fitting slide groove 190 extending in the axial direction, and a lower portion of the inner slide sleeve 188 is provided with a locking member 1.
The slide shaft 194 is engaged via the 92. In the driving means 180 configured as described above, the first port 12
8a, the inner slide sleeve 188 is lowered integrally with the slide shaft 194 (arrow B1).
Direction). When the DC motor 152 rotates, the drive sleeve 184 is driven via the first gear 146.
Is rotated, and the inner slide sleeve 18 is further moved under the action of the drive steel ball 186 and the slide groove 190.
8 and the slide shaft 194 rotate integrally. On the other hand, when air is supplied to the second port 128b, the slide shaft 194 is urged upward (in the direction of arrow B2),
The slide shaft 194 and the inner slide sleeve 1
88 is integrally raised and arranged at a predetermined standby position.
When changing the stroke in the direction of arrow B, the inner slide sleeve 188 and / or slide shaft 194 may be configured in a plurality of stages. FIG. 9 is an overall explanatory diagram of a work machine 202 incorporating a correction head driving device 200 according to the third embodiment of the present invention. Note that the same components as those of the correction head driving device 10 and the working machine 12 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The work machine 202 includes a power supply unit 204 for supplying power to the tool holder 18 and a driving unit 206 for driving the correction head 22.
In order not to interfere with the work by the tool holder 18,
It is integrally fixed to the corner of the machine tool 14. As shown in FIG. 10, the driving unit 206 includes a spindle unit 208 provided in the cylinder 116, and a first gear 146 is fixed on the spindle unit 208. A locking pin 210 is fixed to the lower side of the spindle 208, and the locking pin 210 fits into a guide 214 formed on the side of the slide shaft 212. The slide shaft 212 is supported by a spring 216 and urged downward. In the correction head driving device 200 configured as described above, the tool holder 18 is not used until a series of processing is completed and the processing shifts to processing of the next work (not shown).
Moves to the power supply unit 204 side integrally with the spindle 16 and forms electromagnetic coupling with the power supply unit 204. Thus, in the third embodiment, except that the tool holder 18 moves to the fixed power supply unit 204 side, the correction work of the correction head 22 is performed with high accuracy and certainty. Similar effects can be obtained. The tool can be adjusted by manual operation instead of the driving means 24, 180 and 206. Further, various modifications can be made as necessary, for example, the correction head driving devices 10 and 200 can be incorporated in an automatic tool change mechanism (ATC).

In the correction head driving device for a working machine according to the present invention, the tool holder and the power supply unit are electromagnetically coupled to each other, and power is externally supplied to the detection unit provided on the tool holder. The driving unit is coupled to the driving force transmission unit, and the correction head is driven from the outside. Therefore, the adjustment state of the correction head is directly detected via the detection unit, and the driving unit is controlled based on the detection result, so that the adjustment operation of the correction head is performed with high accuracy and efficiency.

[Brief description of the drawings]

FIG. 1 is an overall perspective explanatory view of a working machine incorporating a correction head driving device according to a first embodiment of the present invention.

FIG. 2 is a partial vertical cross-sectional view of a tool holder included in the working machine according to the first embodiment.

FIG. 3 is an explanatory longitudinal sectional view of a driving force transmitting portion and an electromagnetic coupling portion of the tool holder.

FIG. 4 is a circuit configuration diagram of the tool holder and the controller.

FIG. 5 is a partially longitudinal explanatory view of a driving unit and an electromagnetic coupling unit that constitute the correction head driving device.

FIG. 6 is a sectional view taken along line VV in FIG.

FIG. 7 is an explanatory diagram of an operation of the driving force transmission unit and the electromagnetic coupling unit.

FIG. 8 is a partial longitudinal sectional view illustrating a driving unit and an electromagnetic coupling unit that constitute a correction head driving device according to a second embodiment of the present invention.

FIG. 9 is an overall explanatory diagram of a working machine incorporating a correction head driving device according to a third embodiment of the present invention.

FIG. 10 is a partial vertical cross-sectional view of a driving unit and an electromagnetic coupling unit that constitute the correction head driving device according to the third embodiment.

[Explanation of symbols]

10, 200... Correction head driving device 12, 202.
Work machine 14 ... Machine tool 16 ... Spindle 18 ... Tool holder 20,204 ...
Power supply unit 22: correction heads 24, 180,
206 driving means 26 controller 34 driving force transmitting section 36 detecting section 50 taper drive shaft 60 power unit 64 head housing 72, 112, 142 winding coil 110 electromagnetic coupling section 114, 144 ferromagnetic material 116: cylinder 126: sleeve member 136, 194, 212: slide shaft 140: coupling head 152: DC motor 188: inner slide sleeve

Claims (5)

[Claims] A correction head provided on a tool holder rotatable integrally with a spindle and capable of adjusting a position of a tool in a radial direction of the spindle; and adjusting the correction head by an external driving force. A driving force transmission unit; a detection unit for detecting an adjustment state of the correction head; a power supply unit configured to electromagnetically couple with the tool holder to supply power to the detection unit; And a drive unit detachably attached to the transmission unit and externally adjusting the correction head via the drive force transmission unit. 2. The correction head driving device according to claim 1, further comprising a controller capable of controlling said driving unit based on information from said detection unit by performing wireless communication with said tool holder. Head drive device for work machines that do. 3. The correction head driving device according to claim 1, wherein the tool holder includes a first ferromagnetic material on which a winding is applied, and the power supply unit includes a first ferromagnetic material and a first ferromagnetic material. And a coupling head provided with a second ferromagnetic body provided with a winding constituting electromagnetic coupling. 4. A correction head driving device according to claim 1, wherein said driving means comprises: a rotary coupling portion which engages with said driving force transmitting portion and is rotatable under the action of a rotary drive source; An actuator capable of moving back and forth with respect to the tool holder, wherein the power supply unit is provided integrally with the rotary coupling unit. 5. The correction head driving device according to claim 1, wherein said driving means engages with said driving force transmitting portion under a moving action of said tool holder and is rotatable via a rotary driving source. A correction head driving device for a working machine, comprising: a coupling unit; wherein the power supply unit is provided integrally with the rotary coupling unit.