WO2018221338A1

WO2018221338A1 - Wire feeding device

Info

Publication number: WO2018221338A1
Application number: PCT/JP2018/019787
Authority: WO
Inventors: 佳晃福永; 寿郎宮原; 森田　幸也; 徹志源元
Original assignee: 株式会社ダイヘン
Priority date: 2017-05-31
Filing date: 2018-05-23
Publication date: 2018-12-06
Also published as: JP6874944B2; JP2018202434A

Abstract

A wire feeding device comprising a feeding roll and a pressing roll. A weld wire is sandwiched between the feeding roll and the pressing roll and fed in a prescribed direction. The wire feeding device comprises: a pressing roll holder that supports the pressing roll; a pressing lever that applies pressing force to the pressing roll holder; and a support body that supports the feeding roll, the pressing roll holder, and the pressing lever. The pressing roll holder has a first end part and a second end part that are set apart from each other. The pressing roll holder is capable of rotating about a first axis along which the first end part extends. A force-receiving part that receives the pressing force from the pressing lever is provided to the second end part. The pressing lever is capable of rotating about a second axis. The pressing lever rotates between a pressing position at which the pressing force is applied to the pressing roll holder, and a pressing release position at which rotation of the pressing roll holder about the first axis is permitted.

Description

Wire feeder

The present disclosure relates to a wire feeding device, and more particularly to a feeding device for feeding a welding wire.

Patent Document 1 discloses a feeding device for a welding wire. The conventional wire feeding device disclosed in this document includes a feeding roll and a pressure roll. A welding wire is sandwiched between the feeding roll and the pressure roll, and the feeding roll and the pressure roll rotate in this state. As a result, the welding wire is fed in a desired direction. The pressure roll is supported by the pressure roll holder, and the base end portion of the pressure roll holder is rotatably supported by the feeder main body. A welding wire is hold | maintained between a supply roll and a pressurization roll by the front-end | tip part of a pressurization roll holder being pressed by the pressurization mechanism containing an operation lever.

In the above-described conventional wire feeding device, the operation lever is in a direction orthogonal to the wire feeding direction during use (a state in which the welding wire is sandwiched between the feeding roll and the pressure roll) (Patent Document) 1 in FIG. 2 and FIG. Further, the operation lever (and thus the pressure mechanism) is supported by the feeding apparatus main body so as to be rotatable around an axis parallel to the rotation axis of the feeding roll and the pressure roll. By rotating the operating lever in a predetermined direction (counterclockwise in FIG. 3 of the same document), the pressure roll holder is released from the pressurized state, and maintenance such as replacement of the welding wire and replacement of the pressure roll is possible. Become.

Conventionally, the wire feeder is attached, for example, in the vicinity of a welding torch provided at the arm tip of a welding robot. In this case, when the welding robot operates, it is desirable that the wire feeding device is small in order to avoid interference with objects around it. However, in the wire feeding device of Patent Document 1, the operation lever always extends in a direction perpendicular or substantially perpendicular to the wire feeding direction, and is likely to interfere with surrounding objects. The wire feeding device having such a configuration still has room for improvement in further downsizing.

JP2015-131325A

This disclosure has been proposed under such circumstances. Then, one subject of this indication is providing the wire feeder suitable for size reduction. Note that the subject of the present disclosure is not limited to this. It is possible to derive other problems according to various teaching contents according to the present disclosure.

The wire feeding device provided according to one aspect of the present disclosure includes a feeding roll that rotates around a first direction and a pressure roll that pressurizes the feeding roll. The welding wire is sandwiched between the feeding roll and the pressure roll and fed in a second direction orthogonal to the first direction. Furthermore, the wire feeding device applies a pressure to the pressure roll holder so that the pressure roll holder rotatably supports the pressure roll and the pressure roll pressurizes the feed roll. And a support for supporting the feeding roll, the pressure roll holder, and the pressure lever. The pressure roll holder has a first end and a second end that are spaced apart from each other in the longitudinal direction. The pressure roll holder is rotatable with respect to the support body around a first axis extending from the first end along the first direction. The second end portion is provided with a force receiving portion that receives pressure from the pressure lever. The pressure lever is rotatable with respect to the support body around a second axis along a third direction orthogonal to both the first direction and the second direction. The pressure lever is rotatable between a pressure position that applies pressure to the pressure roll holder and a pressure release position that allows the pressure roll holder to rotate around the first axis. It is.

Other features and advantages of the present disclosure will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is the schematic which shows the welding robot with which the wire feeding apparatus which concerns on this indication was integrated. It is a front view which shows an example of the said wire feeder. It is a perspective view of the said wire feeder. It is a front view which shows the said wire feeder in a pressurization cancellation | release state (state in which a pressurization lever exists in a pressurization cancellation | release position). It is a perspective view which shows the said wire feeder in a pressure release state. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 2. It is the figure which expanded a part of structure shown in FIG. FIG. 3 is a sectional view taken along line VIII-VIII in FIG. 2. FIG. 4 is a cross-sectional view taken along line IX-IX in FIG. 3.

Hereinafter, preferred embodiments will be specifically described with reference to the drawings.

FIG. 1 shows an example of a welding robot B1 incorporating a wire feeding device A1. The welding robot B1 shown in the figure includes at least one movable arm 7. That is, the welding robot B 1 may include a plurality of arms 7 or a single arm 7. Each arm 7 has at least one joint so that a desired posture can be taken, and is configured to have a plurality of joints according to circumstances. A welding torch 8 is provided at the tip of the arm 7. For example, the wire feeder A1 is disposed between the distal end of the arm 7 and the proximal end of the welding torch 8, but the present disclosure is not limited thereto. A welding wire (hereinafter simply referred to as a “wire”) W is supplied to the welding torch 8 via, for example, a power cable 9. Further, the wire W is fed through the welding torch 8 by the wire feeding device A1, and then fed out from the opening of the tip of the welding torch 8.

A power supply tip is provided inside the tip of the welding torch 8. The welding power is supplied to the wire W from the power supply device via the power cable 9 and the power feed tip. The welding torch 8 is supplied with a shielding gas. The shield gas is supplied from, for example, a gas cylinder, flows through the welding torch 8, and is ejected to the outside from the opening of the tip of the torch.

The wire feeding device A1 is housed inside the housing case 51 (see FIG. 1). As shown in FIGS. 2 to 9, the wire feeding device A1 includes, for example, a feeding roll 11, a pressure roll 12, a pressure roll holder 20, a pressure lever 30, a pressure mechanism 40, a support 50, and a motor. 60. The support body 50 is fixed to the housing case 51. The storage case 51 is provided with an opening / closing door 511. For example, during maintenance, the door 511 can be opened to access the pressure roll 12 and the like. 2 and 4 are views seen from the front side of the opening / closing door 511, and the opening when the opening / closing door 511 is opened is indicated by a virtual line (two-dot chain line). As will be described later, for example, three axes (first to third axes) are determined for the wire feeder A1.

The supply roll 11 cooperates with the pressure roll 12 to send out the wire W in a predetermined direction. The feed roll 11 is fixed to, for example, the output shaft 61 of the motor 60 (see FIG. 9). The output shaft 61 extends along the first direction X (see FIGS. 3 and 5). During operation, the output shaft 61 rotates around the first direction X. As the output shaft 61 rotates, the feed roll 11 also rotates around the first direction X.

As shown in FIG. 5, an endless annular groove 112 is formed on the outer peripheral surface 111 of the feed roll 11. The groove 112 is recessed from the outer peripheral surface 111 of the feed roll 11, and the cross-sectional shape thereof is, for example, a shape that extends outward in the radial direction of the output shaft 61 of the motor 60. The groove 112 is configured to be suitable for guiding the wire W.

The pressure roll 12 is disposed on the opposite side of the feed roll 11 with the wire W interposed therebetween. The pressure roll 12 is supported by the pressure roll holder 20 so as to be rotatable around the third axis O3. The third axis O3 is parallel to the first direction X. The pressure roll 12 rotates around the first direction X.

The outer peripheral surface 121 of the pressure roll 12 faces the outer peripheral surface 111 of the feed roll 11. As shown in FIG. 5, an endless annular groove 122 is formed on the outer peripheral surface 121 of the pressure roll 12. The cross-sectional shape of the groove 122 is, for example, a shape that spreads outward in the radial direction of the third axis O3. With the wire W sandwiched between the groove 122 of the pressure roll 12 and the groove 112 of the feed roll 11, the pressure roll 12 and the feed roll 11 rotate. Thereby, the wire W is sent in a predetermined direction. Unlike this embodiment, the wire guide groove may be formed only on the outer peripheral surface of either the pressure roll 12 or the feed roll 11. For example, the wire W may be sandwiched between the outer peripheral surface 121 and the groove 112 of the feeding roll 11 without forming a groove on the outer peripheral surface 121 of the pressure roll 12. Further, it is possible to adopt a configuration in which no groove for wire guide is provided in any roll.

The rotation direction of the pressure roll 12 is opposite to the rotation direction of the feed roll 11. When the pressure roll 12 and the feed roll 11 rotate with the wire W sandwiched therebetween, a frictional force acts on the wire W from the pressure roll 12 and the feed roll 11, and the wire W is fed. The feeding direction (second direction Y) of the wire W is, for example, perpendicular to the first direction X. In FIG. 2, the wire W is fed rightward.

As shown in FIG. 9, a pair of wire guides 52 are provided along the feeding direction of the wire W (see also FIGS. 3, 4 and 8). Each wire guide 52 guides the wire W supplied via the power cable 9. A hole for inserting the wire W is formed in the wire guide 52. The wire W is appropriately guided to the outside of the wire feeding device A1 by the pair of wire guides 52. Thereafter, the wire W passes through the inside of the welding torch 8 and is sent out from the tip of the welding torch 8.

The pressure roll holder 20 is supported so as to be rotatable with respect to the support 50 (see FIGS. 4 and 5). The pressure roll holder 20 rotates around the first axis O1. The first axis O 1 is located on the proximal end side of the pressure roll holder 20 and extends in parallel with the first direction X. Thereby, the pressure roll holder 20 can be rotated around the first direction X. A force receiving portion 21 is provided on the distal end side of the pressure roll holder 20. The force receiving portion 21 is a portion that receives pressure from the pressure lever 30.

As shown in FIG. 9, the pressure roll holder 20 is provided with a rotating shaft portion 22 that rotatably supports the pressure roll 12. Thereby, the pressure roll 12 can rotate around the third axis O3. In the pressure roll holder 20, the third axis O 3 (and thus the rotating shaft part 22) is disposed between the first axis O 1 and the force receiving part 21. In the example shown in the figure, the distance between the third axis O3 and the first axis O1 is set to be smaller than the distance between the third axis O3 and the force receiving portion 21.

The pressure lever 30 is rotatably supported by the housing 41 of the pressure mechanism 40. The pressure lever 30 can rotate around the second axis O2. As will be described below, it is possible to apply pressure from the pressure roll 12 toward the feed roll 11 by rotating the pressure lever 30 in a predetermined direction. The second axis O2 is located on the opposite side of the first axis O1 with respect to the feed roll 11 in the second direction Y. The second axis O2 is parallel to the third direction Z. The third direction Z is orthogonal to both the first direction X and the second direction Y.

The pressure lever 30 is rotatable between a pressure position (see FIGS. 2 and 3) and a pressure release position (see FIGS. 4 and 5). The pressure position is a position where the pressure lever 30 applies pressure to the pressure roll holder 20. When in the third direction Z, the pressure lever 30 (upper wall 31) overlaps with the pressure roll holder 20 when in the pressure position. In this state, rotation of the pressure roll holder 20 around the first axis O 1 (particularly clockwise rotation in FIG. 9) is limited by the pressure lever 30. On the other hand, when the pressure lever 30 is in the pressure release position (FIG. 5), the pressure roll holder 20 and the pressure lever 30 do not interfere with each other, and the pressure roll holder 20 is around the first axis O1. It can be rotated. In other words, when the pressure lever 30 is in the pressure release position, the pressure lever 30 (particularly the upper wall 31) does not overlap the pressure roll holder 20 in the third direction Z view. When the pressure lever 30 is in the pressure release position, the pressure lever 30 at least partially overlaps the pressure mechanism 40 in the first direction X, but does not overlap the pressure roll holder 20. The maximum angle at which the pressure lever 30 can rotate around the second axis O2 is, for example, 90 °, but the present disclosure is not limited to this.

As shown in FIGS. 2 to 5 and FIG. 9, the pressure lever 30 has an upper wall 31 and a vertical wall (side wall) 32. Further, an extension portion 33 and a locking portion (first locking portion) 34 are provided inside the vertical wall 32 (see, for example, FIG. 5). The upper wall 31 has a base end connected to the rotating shaft portion 35 and extends substantially horizontally to the tip. The rotation shaft portion 35 is fitted into an attachment hole 411 formed in the upper portion of the housing 41 and can rotate relative to the housing 41, but cannot move in the axial direction. A protrusion 311 is formed on the lower surface of the base wall on the base end side (see FIGS. 8 and 9). The protruding portion 311 is a portion raised in the third direction Z with respect to the peripheral surface. In the example shown in FIG. 9, the protruding portion 311 protrudes in the direction (direction Z1) from the pressure roll 12 toward the feeding roll 11. As shown in FIG. 8, the protruding portion 311 has, for example, a strip shape extending along the width direction of the upper wall 31. As shown in FIGS. 3 and 5, a recess 312 is formed on the top surface of the top end of the upper wall 31.

As shown in FIG. 2, the vertical wall 32 has, for example, a substantially triangular shape (a right triangle shape in the illustrated example), but the present disclosure is not limited thereto. The vertical wall 32 is connected to one end side in the width direction of the upper wall 31. In the example shown in FIG. 6, the vertical wall 32 is connected to the left edge of the upper wall 31 and extends downward from the upper wall 31. The extending portion 33 protrudes from the vicinity of the lower end of the vertical wall 32 (near the lower vertex of the triangle) in the thickness direction (horizontal direction) of the vertical wall 32.

The locking portion 34 of the pressure lever 30 is provided at the tip (free end) of the extending portion 33. As shown in FIGS. 6 and 7, the locking portion 34 protrudes upward (direction Z 2) from the upper surface of the extending portion 33. A locking portion (second locking portion) 53 protruding downward (direction Z1) is provided at an appropriate position of the support body 50. When the pressure lever 30 is in the pressure position, the locking portion 34 of the pressure lever 30 is locked by the locking portion 53 of the support 50. By the engagement of the two locking

portions

53 and 34, the rotation operation of the pressure lever 30 from the pressure position to the pressure release position is limited. As can be understood from FIGS. 2, 5 and 6, the locking portion 53 of the support body 50 (and thus the locking portion 34 of the pressure lever 30) is based on the feed roll 11 in the second direction Y. It is located on the opposite side to the second axis O2.

As shown in FIG. 7, an inclined surface (first inclined surface) 341 is formed on the locking portion 34. Further, the locking portion 53 is formed with an inclined surface (second inclined surface) 531. The inclined surface 341 of the locking portion 34 is inclined so as to be displaced in the direction Z1 toward the front (right side in FIG. 7) in the direction of rotation from the pressure release position of the pressure lever 30 to the pressure position. . The inclined surface 531 of the locking portion 53 is inclined so as to be displaced in the direction Z1 toward the right side in FIG. As can be easily understood, the two inclined surfaces 341 and 531 temporarily abut each other before the state shown in FIG. 7 is reached. The phantom line in FIG. 7 shows a state where the pressure lever 30 is rotating from the pressure release position toward the pressure position.

The pressurizing mechanism 40 gives an urging force to the pressurizing lever 30 in the direction Z1. As shown in FIGS. 4 and 9, the pressurizing mechanism 40 includes, for example, a housing 41, an urging member 42, an adjusting screw 43, and an adjusting disk 44. The housing 41 is supported by the support 50 and is configured to be movable within a predetermined range in the third direction Z with respect to the support. The housing 41 supports the pressure lever 30 at its upper end. Therefore, as the housing 41 is displaced along the third direction Z, the pressure lever 30 is similarly displaced. The pressure lever 30 can rotate relative to the housing 41 around the second axis O2. The pressure lever 30 may not be able to move relative to the housing 41 in the third direction Z.

As shown in FIG. 9, the urging member 42 is provided inside the housing 41. In the example shown in the figure, the urging member 42 is disposed near the lower end of the housing 41. The upper end of the biasing member 42 is fitted in an annular recess 54 formed in the support body 50, and the lower end is in contact with the adjustment disk 44. The urging member 42 receives a reaction force from the support body 50 and urges the housing 41 in a predetermined direction via the adjustment disk 44. In the example shown in the figure, the biasing member 42 biases the housing 41 downward. The urging member 42 is a member that uses the elasticity of an object, and is, for example, a coil spring (particularly a compression coil spring).

The adjustment screw 43 is provided at the lower end of the housing 41 and is supported by the housing 41. The adjustment screw 43 can rotate relative to the housing 41 around the axis of the screw, but does not move in the axial direction. The adjustment disc 44 is a member having a screw hole, and the screw portion of the adjustment screw 43 is screwed into the screw hole. The adjustment disk 44 is built in the lower end of the housing 41 and cannot rotate relative to the housing 41. When the adjustment screw 43 is rotated in one direction (for example, clockwise when viewed in the direction Z2), the adjustment disk 44 comes close to the annular recess 54 of the support body 50, and when the adjustment disk 44 is rotated in the opposite direction, the adjustment disk 44 is supported by the support body. Separated from the 50 annular recesses 54. Thus, the biasing force of the biasing member 42 can be adjusted by changing the length of the biasing member 42 (the dimension along the direction Z).

Next, the operation of the above-described embodiment will be described.

The pressure lever 30 is rotatable around the second axis O2 along the third direction Z. Specifically, the pressure lever 30 has a pressure position (pressure is applied to the pressure roll holder 20) and a pressure release position (rotation around the first axis O1 of the pressure roll holder 20 is allowed. It is possible to rotate between. As shown in FIG. 3, in the pressure position, the pressure lever 30 is configured to extend along the feeding direction of the wire W as a whole. That is, the pressure lever 30 is not configured to unduly project in a direction orthogonal to the feeding direction of the wire W. This contributes to the miniaturization of the wire feeder A1.

On the other hand, when the pressure lever 30 is in the pressure release position, when the wire feeder A1 is viewed from the front side (FIG. 4), the pressure lever 30 (particularly the vertical wall 32) is the opening portion of the housing case 51 ( A posture orthogonal to the virtual line in FIG. 4, that is, a posture in which the area of the region overlapping the opening is minimized. The rotation axis (second axis O2) of the pressure lever 30 is the same as the rotation axis (first axis O1) of the pressure roll holder 20 with respect to the feed roll 11 in the second direction Y. Is on the opposite side. According to such a configuration, the pressure lever 30 does not overlap the pressure roll holder 20, the feed roll 11, or the pressure roll 12 when in the pressure release position. Therefore, during maintenance such as replacement of the wire W and the pressure roll 12, the pressure lever 30 does not hinder the work, and the maintenance work can be performed efficiently.

The pressurizing mechanism 40 (housing 41) can rotatably support the pressurizing lever 30 and can adjust the pressure applied to the pressurizing lever 30 in the direction Z1. Here, the adjustment of the applied pressure by the pressurizing mechanism 40 can be performed independently of the rotation of the pressurizing lever 30 (that is, without affecting the rotating function). Therefore, the adjustment of the applied pressure by the pressurizing mechanism 40 can be accurately set to a desired value.

The pressure roll holder 20 is rotatable about the first axis O1 on one end side in the longitudinal direction, and has a force receiving portion 21 that receives pressure from the pressure lever 30 on the other end side in the longitudinal direction. The pressure roll 12 is positioned near the first axis O1 between the first axis O1 of the pressure roll holder 20 and the force receiving portion 21, and rotates around the third axis O3 along the first direction X. Supported as possible. According to such a configuration, the pressure applied to the force receiving portion 21 from the pressure lever 30 can be amplified and acted from the pressure roll 12 toward the feed roll 11.

The pressure lever 30 (upper wall 31) has a protrusion 311 (see FIGS. 8 and 9). The protruding portion 311 has a shape protruding in the direction Z1 from its peripheral portion, and comes into contact with the force receiving portion 21 when the pressure lever 30 takes the pressure position. According to such a configuration, the pressure point from the pressure lever 30 (projecting portion 311) to the pressure roll holder 20 (power receiving portion 21) does not change according to the adjustment value of the applied pressure, for example, It becomes a fixed position. Thereby, it is possible to accurately set the pressure applied from the pressure roll 12 toward the feed roll 11 so as to be a desired value, and it is possible to realize more accurate wire feeding.

As shown in FIG. 8, in the force receiving portion 21, at least a part of the entry side end (right end in the figure) of the pressure lever 30 is inclined. According to such a configuration, when the pressure lever 30 rotates around the second axis O2 toward the pressure position, the pressure lever 30 (projecting portion 311) contacts the inclined surface of the force receiving portion 21. It is possible to smoothly rotate to the final position while touching.

As shown in FIG. 6, the support body 50 has a locking portion 53 protruding in the direction Z1. The pressure lever 30 has a locking portion 34 protruding in the direction Z2. When the pressure lever 30 is in the pressure position, the locking portion 34 is locked by the locking portion 53. According to such a structure, it can restrict | limit so that the pressurization lever 30 in a pressurization position does not raise | generate the rotation operation | movement which goes to a pressurization cancellation | release position. Therefore, the pressure roll holder 20 is appropriately pressurized.

7, an inclined surface 341 is formed on the locking portion 34 of the pressure lever 30, and an inclined surface 531 is formed on the locking portion 53 of the support 50. According to such a configuration, when the pressure lever 30 rotates toward the pressure position, the locking portion 34 is urged toward the direction Z1 by the contact between the inclined surface 341 and the inclined surface 531. . As a result, the pressure lever 30 is elastically displaced in the direction Z1, the locking portion 34 gets over the locking portion 53, the pressure lever 30 is disposed at the pressure position, and a locked state is established. Thus, the pressure lever 30 can be brought into the locked state only by rotating the pressure lever 30 toward the pressure position.

The locking portion 53 of the support 50 is located on the opposite side of the second axis O2 with respect to the feed roll 11 in the second direction Y (see, for example, FIG. 5). In other words, the locking part 53 and the locking part 34 are located at positions relatively distant from the second axis O2. Further, as shown in FIG. 5, a recess 312 is formed at the tip of the pressure lever 30 (upper wall 31), and the recess 312 is from the second axis O 2 to the same extent as the locking portion 34. In a remote location. According to this configuration, when the locking portion 53 is locked to the locking portion 53, the pressing lever 30 can be rotated with a relatively small force by picking and operating the concave portion 312.

As mentioned above, although embodiment of this indication was described, the said embodiment is only an illustration and this indication is not limited to the said embodiment. It will be apparent to those skilled in the art that the specific configuration of each part according to the present disclosure can be modified in various ways.

Claims

A feed roll that rotates about a first direction;
A pressure roll that pressurizes the feeding roll, sandwiching the wire with the feeding roll, and feeding the wire in a second direction orthogonal to the first direction;
A pressure roll holder that rotatably supports the pressure roll;
A pressure lever that applies pressure to the pressure roll holder so that the pressure roll pressurizes the feed roll; and
A support for supporting the feed roll, the pressure roll holder, and the pressure lever;
The pressure roll holder has a first end and a second end spaced apart from each other in the longitudinal direction, and the pressure roll holder extends in the first end along the first direction. Around the one axis, it is rotatable with respect to the support, and the second end has a force receiving portion that receives pressure from the pressure lever,
The pressure lever is rotatable with respect to the support body around a second axis along a third direction orthogonal to both the first direction and the second direction,
The pressure lever is rotatable between a pressure position that applies pressure to the pressure roll holder and a pressure release position that allows the pressure roll holder to rotate around the first axis. A wire feeding device.
The wire feeding device according to claim 1, wherein the second axis is located on the opposite side of the first axis with respect to the feeding roll in the second direction.
In the configuration further including a pressure mechanism that rotatably supports the pressure lever, the pressure mechanism applies pressure to the pressure lever in a direction from the pressure roll toward the feeding roll. The wire feeding device according to claim 1, wherein the wire feeding device is configured to perform the following.
The pressure lever has a first locking portion protruding in the third direction, the support has a second locking portion protruding in the third direction, and the pressure lever is in the pressure position. The wire feeding device according to any one of claims 1 to 3, wherein the first locking portion and the second locking portion are engaged with each other.
The said 1st latching | locking part is formed with the 1st inclined surface, The said 2nd latching | locking part is formed with the 2nd inclined surface which can contact | abut to the said 1st inclined surface. Wire feeding device.
The wire feeding device according to any one of claims 1 to 5, wherein the pressure lever includes a protrusion that protrudes in the third direction and that contacts the force receiving portion at the pressure position. apparatus.