JP2016034196A - Tape winding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tape winding apparatus capable of improving working efficiency of tape winding work around an electric wire and being miniaturized.SOLUTION: A tape winding apparatus 100 includes: a wound body 101 formed by lap-winding a self-fusing tape 101T having insulation properties for coating an electric wire; a case 102 for rotatably supporting the wound body so that the self-fusing tape is drawn out from the wound body with tensile force; an arm 108 having a tip portion for holding a tip of the self-fusing tape extended and drawn out from the case in a direction for drawing out the self-fusing tape; and sliding plates 106A, 106B which are respectively arranged on positions adjacent to the tip portion, and when the tip portion is opposed to the electric wire, slide along an external peripheral surface of the electric wire so that the arm and the case are rotated around an axis in a longitudinal direction of the electric wire and the self-fusing tape is drawn out and stuck to the electric wire.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tape winding apparatus.

  When the insulation coating of an overhead wire is deteriorated or damaged, repair work may be performed by winding an insulation tape around the installed overhead wire. This operation is generally performed by gripping and winding a roll of insulating tape with an insulating operation rod. However, when the winding body and the operation rod do not have a positioning jig or the like for the electric wire, it is difficult to wind the winding body while stabilizing the posture of the winding body, and the work load becomes large for the operator.

  In particular, a self-bonding tape is used for the insulation tape for overhead wires, and in order to wind the tape so that it can be applied, it is necessary to wind the tape while pulling it with a certain level of force. More difficult to do. The self-bonding tape is a tape that is made of butyl rubber and exhibits an adhesive force at an overlapping portion of the tapes by being wound while being pulled.

  From such a background, it is possible to wind a self-bonding tape around an overhead electric wire by attaching a device having a hollow rotating body that rotates the periphery of the electric wire to the tip of the operation rod and rotating the hollow rotating body with a gear mechanism. A tape winding device or the like has been proposed (see, for example, Patent Document 1).

JP-A-8-275324

  However, since the tape winding device shown in Patent Document 1 requires a gear mechanism and has a structure integrated with the operation rod, the tape winding device itself is increased in size, and the electric wire is installed by vertical drawing. In the case of being installed (vertically) or in a narrow place, there is a problem that it is difficult to perform the tape winding operation using the tape winding device.

  Accordingly, an object of the present invention is to provide a tape winding device that can improve the working efficiency of the tape winding operation of the self-bonding tape to the electric wire and can be miniaturized.

  The main present invention for solving the above-mentioned problems is that a self-fusing tape having an insulating property for covering an electric wire is overlapped and wound, and the self-fusing tape has tension from the winding. A case that rotatably supports the winding body so as to be pulled out, and a tip that extends from the case toward a direction in which the self-bonding tape is pulled out and holds the leading end of the self-bonding tape that is pulled out. An arm having a distal end portion, and disposed at a position adjacent to the distal end portion, and when the distal end portion faces the electric wire, the arm and the case rotate about a longitudinal axis of the electric wire, A tape winding apparatus comprising: a sliding plate that slides along an outer peripheral surface of the electric wire so that the self-bonding tape is attached to the electric wire while being pulled out.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  According to the tape winding apparatus of the present invention, it is possible to improve the work efficiency of the tape winding work of the self-bonding tape to the electric wire and to reduce the size.

It is a figure which shows the structure of the tape winding apparatus in embodiment of this invention. It is a figure which shows the structure of the operating rod in embodiment of this invention. It is a figure (perspective view) which shows the tape winding operation | work in embodiment of this invention. It is a figure (sectional view) which shows the tape winding operation | work in embodiment of this invention. It is an image figure explaining the force which acts on the sliding plate in embodiment of this invention.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== About the structure of the tape winding device ===
The tape winding apparatus according to the present embodiment is used for tape winding work of a self-bonding tape to an electric wire, and improves the work efficiency. The self-bonding tape is a tape made of butyl rubber as described above, and has a characteristic of exerting an adhesive force at an overlapping portion of the tape by being wound around an electric wire while being pulled.

  An example of the configuration of the tape winding apparatus 100 according to the present embodiment is shown in FIG. In the figure, the P1 axis is the direction in which the self-bonding tape 101T (hereinafter referred to as “tape 101T”) is drawn from the wound body 101 (hereinafter referred to as “tape pulling direction P1”), and the P2 axis is wound. The width direction of the body 101 (hereinafter referred to as “winding axis direction P2”), the P3 axis is an axis indicating a direction orthogonal to the P1 axis and the P2 axis.

  A tape winding apparatus 100 according to this embodiment includes a winding body 101, a case 102, an arm 108, and sliding plates 106A and 106B. Then, the case 102 rotatably supports the winding body 101 so that the tape is pulled out with tension, and the arm 108 extends in a direction in which the tape is pulled out from the case 102, and is attached to the distal end portion 108 </ b> T of the arm 108. The sliding plates 106A and 106B are attached.

  In the tape winding apparatus 100 according to the present embodiment, the friction roller 107 is disposed in the case 102 so that the tape 101T is pulled out with tension.

  The wound body 101 is a tape that is held in an overlapped state.

  The wound body 101 is supported by the case 102, and when the tape 101T is pulled, the tape 101T is sequentially fed out in the tape drawing direction P1. In addition, 101T in FIG. 1 represents the tape pulled out from the wound body 101. FIG.

  The case 102 supports the winding body 101 and accommodates the winding body 101 so that the tape 101T is pulled out from the winding body 101 with tension.

  In addition, the case 102 is formed with a hole 103 and a feeding port 104.

  The hole 103 is a cylindrical hole that penetrates the case 102 in the winding axis direction P <b> 2 to support the wound body 101. Then, the case 102 accommodates the wound body 101 so that the tape is wound around the hole 103.

  The hole 103 is provided through the winding shaft of the winding body 101 so that the winding body 101 is rotatably supported. The case 102 is formed of a material with low frictional resistance on the contact surface with the wound body 101 around the hole 103 so that when the tape 101T is pulled out from the wound body 101, the wound body 101 is removed from the hole 103. The winding body 101 is supported so that it can freely rotate around.

  The hole 103 has a configuration for supporting the winding body 101 and also a configuration for detachably attaching a tip of an operation rod 200 described later to grip the tape winding device 100.

  The delivery port 104 is a hole formed in the case 102 so that the tape 101T is drawn from the wound body 101 in the tape drawing direction P1. That is, when the tape 101T is pulled, the wound body 101 rotates around the hole 103 around the P2 axis, and the tape 101T is pulled out from the delivery port 104.

  The arm 108 is a portion extending from the case 102 in the tape drawing direction P1 in order to attach the sliding plates 106A and 106B. The arm 108 extends from the lower position of the wound body 101 of the case 102 in the tape drawing direction P1, and the tip 108T of the arm 108 in the tape drawing direction P1 is pulled out during the tape winding operation. In order to hold the tip of the tape 101T, it has a shape extending in the P3 direction.

  Further, the distal end portion 108T of the arm 108 has a cutter 105 for cutting the tape.

  The cutter 105 has a plurality of sharpened shapes along the winding axis direction P2 at the distal end portion 108T of the arm 108. The cutter 105 makes it possible to cut the drawn tape 101T by pressing the drawn tape 101T against the sharp-shaped portion.

  The sliding plates 106 </ b> A and 106 </ b> B are members disposed at positions adjacent to the distal end portion 108 </ b> T of the arm 108 in order to stabilize the posture of the tape winding device 100 during the tape winding operation.

  Specifically, the sliding plates 106A and 106B are arranged in a pair with the arm 108 sandwiched in the longitudinal direction of the electric wire in a state where the distal end portion 108T faces the electric wire.

  In addition, the sliding plates 106A and 106B have a shape along the electric wire on the tape drawing direction P1 side, and have a sliding surface facing a half or less surface of the outer peripheral surface of the electric wire. The sliding plates 106A and 106B are attached to the distal end portion 108T using a fixing member (not shown) so that the sliding surface extends in a direction parallel to the winding axis direction P2. That is, when the front end portion 108T is opposed to the electric wire, the sliding plates 106A and 106B come into contact with the electric wire, and the winding axis direction P2 of the tape winding device 100 coincides with the longitudinal direction of the electric wire.

  Then, the sliding plates 106A and 106B are configured so that the arm 108 and the case 102 are in the longitudinal direction of the electric wire by the rotational force applied by the operator in a state where the distal end portion 108T faces the electric wire during the tape winding operation. The tape 101T slides along the outer peripheral surface of the electric wire so that the tape 101T is attached to the electric wire while being pulled out.

  In addition, the shape along the electric wire of a sliding surface means that the electric wire and a fixed area | region are concave shapes which can carry out a surface contact or a line contact. However, the shape of the sliding surface does not necessarily have to be a concave shape when the moment about the P2 axis acting on the tape winding device 100 can be received.

  The friction roller 107 is provided so that the tape 101T is pulled out from the wound body 102 with tension.

  Specifically, the friction roller 107 is attached to the case 102 via a bearing so as to press the tape 101T drawn from the winding body 101 against the winding body 101 side. Then, the friction roller 107 generates a drag force, for example, by a frictional force against the force to pull out the tape 101T so that the tape 101T is pulled out with tension.

  The case 102, the arm 108, and the sliding plates 106A and 106B are formed of an insulating material, for example, a plastic material such as polyethylene, in order to prevent electric leakage from the electric wire to the worker.

=== About the structure of the operation bar ===
In the present embodiment, the tape winding operation is performed by rotating the tape winding apparatus 100 around the electric wire using the insulating operation rod 200.

  With reference to FIG. 2, an example of a configuration of the operation rod 200 according to the present embodiment will be described.

  The operation rod 200 includes an operation lever 201, a first connecting portion 202, a connecting rod 203, an operating rod 204, a second connecting portion 205, a first gripping portion 206A, and a second gripping portion 206B.

  Specifically, in the operation rod 200, the operation lever 201 and the connection rod 203 are attached to the base side (the handle side) of the operation rod 204 via the first connection portion 202, and the operation rod 204 has an end portion side ( The connecting rod 203, the first gripping portion 206A, and the second gripping portion 206B are attached to the tape winding device 100 via the second connecting portion 205.

  Then, the operating rod 200 operates the second gripping portion 206B by the operation of the operating lever 201 using the link mechanism, and grips the tape winding device 100.

  Here, the 1st connection part 202 connects the operation lever 201 and the connection rod 203 rotatably with respect to the operation rod 204 using a connection pin. When the operation lever 201 is operated, the connecting rod 203 is operated by the link mechanism via the first connecting portion 202.

  Moreover, the 2nd connection part 205 connects the connection rod 203, the 1st holding part 206A, and the 2nd holding part 206B rotatably with respect to the operation rod 204 using a connection pin. When the connecting rod 203 is operated, the second gripping portion 206B is operated by the link mechanism via the second connecting portion 205.

  Accordingly, when the operator operates the operation lever 201 in a direction approaching the operation rod 204 (R1 direction in FIG. 2), the connecting rod 203 follows the operation lever 201 and moves along the operation rod 204 (see FIG. (R2 direction in 2). When the connecting rod 203 moves in the direction along the operation rod 204 (R2 direction in FIG. 2), the second gripping portion 206B follows the connecting rod 203 and approaches the first gripping portion 206A ( (R3 direction in FIG. 2).

  With the above configuration, the operating rod 200 can grip the tape winding device 100 with the first gripping portion 206A and the second gripping portion 206B by the operation of the operation lever 201 by the operator. When the operating rod 200 is mounted on the tape winding apparatus 100, the operator operates the second gripping portion 206B using the operation lever 201, and the first gripping is performed in the hole 103 of the tape winding apparatus 100. This is done by passing the tips of the portion 206A and the second gripping portion 206B.

=== About tape winding work ===
Next, with reference to FIG. 3, FIG. 4, FIG. 5, an example of the operation | work which winds a tape around an electric wire using the tape winding apparatus which concerns on this embodiment is demonstrated.

  FIG. 3 is a perspective view showing the tape winding operation. The Q axis in FIG. 3 represents the longitudinal direction of the electric wire 300. An arrow M in FIG. 3 represents a direction in which the tape winding device 100 is rotated.

  FIG. 4 shows the tape winding operation by a cross section in a direction perpendicular to the Q axis of the electric wire 300. In FIG. 4, the tape winding device 100 indicated by a broken line represents a change in the positional relationship with the electric wire 300 when the tape winding device 100 is rotated. 4, M1, M2, and M3 represent directions in which the tape winding apparatus 100 moves in time series during the tape winding operation. Also, (A), (B), (C), and (D) in FIG. 4 indicate the positions of the tape winding device 100 when the tape winding device 100 moves in time series with M1, M2, and M3. Represent.

  The tape winding operation according to the present embodiment is performed by an operator holding the tape winding device 100 with the operation rod 200 and winding the tape winding device 100 around the electric wire 300.

  Specifically, the tape winding operation is performed as follows.

  First, the worker wears insulating gloves and applies an adhesive at an initial position where the tape of the electric wire 300 is wound.

  Then, the operator brings the end of the tape 101T drawn from the winding body 101 into contact with the position where the adhesive is applied, so that the tip 108T of the tape winding device 100 faces the electric wire 300. The tape winding device 100 is disposed (state (A) in FIG. 4).

  After the end portion of the tape 101T is fixed to the electric wire 300, the operator holds the tape winding device 100 with the operation rod 200, and the tape so that the front end portion 108T of the tape winding device 100 faces the electric wire 300. The tape 101T is wound around the electric wire 300 by rotating the winding device 100 around the axis in the longitudinal direction Q of the electric wire 300 to M1, M2, and M3.

  In addition, when the front-end | tip part 108T is facing the electric wire 300, since the winding axis direction P2 of the tape winding apparatus 100 and the longitudinal direction Q of the electric wire 300 have faced the same direction, it is taped around the electric wire 300 by the said operation | work. 101T can be wound.

  Here, every time the worker makes one turn around the electric wire 300, the operator retakes the tape winding device 100 with the operation rod 200. That is, the operator separates the tape winding device 100 from the first gripping portion 206A and the second gripping portion 206B of the operation rod 200 at the position (D) in FIG. 4, and moves to the position (A) in FIG. The tape winding device 100 is re-gripped from the side. The state in which the hole 103 of the tape winding device 100 is gripped by the first gripping portion 206A and the second gripping portion 206B of the operation rod 200 is a loose fitting state. Therefore, it is not necessary to pick up the tape winding apparatus 100 while the tape winding apparatus 100 is rotated to M1, M2, and M3.

  Then, the operator repeats the work and winds the tape 101T around the electric wire 300 so that there is no uncovered region while shifting the winding position of the tape 101T in the longitudinal direction Q of the electric wire 300. At this time, the operator causes the tapes 101 </ b> T to partially overlap each other at the portion where the electric wire 300 is wound in the longitudinal direction Q.

  Finally, when the winding of the tape 101T around the electric wire 300 is completed, the operator uses the cutter 105 to cut the tape 101T.

  Through the above steps, the tape can be wound around a desired position of the electric wire 300 using the tape winding device 100.

  In this tape winding operation, the tape winding apparatus 100 operates as follows.

  When the rotating force is applied to the tape winding device 100 in the direction in which the worker rotates the periphery of the electric wire 300 (around the axis in the longitudinal direction Q of the electric wire 300), the tape winding device 100 is caused by the drag from the tape 101T wound around the electric wire 300. Then, the tape 101T is sequentially pulled out from the wound body 101.

  At this time, the friction roller 107 generates a drag force F ′ due to a frictional force against the force to pull out the tape 101T so that the tape 101T is pulled out with tension. As a result, the tape 101T is sequentially pulled out in a state having the tension F when it is pulled with a certain force or more. Then, the tape 101T is wound around the electric wire in a state having a tension F, and the wound tape 101T generates tension so that the tape 101T is pulled out from the wound body 101.

  And the tape 101T wound around the electric wire 300 is affixed sequentially in the part where the wound tapes 101T overlap.

  In this tape winding operation, the sliding plates 106A and 106B function to stabilize the posture of the tape winding apparatus 100.

  FIG. 5 is an image diagram for explaining the force acting on the sliding plates 106A and 106B during the tape winding operation. In FIG. 5, for easy understanding, the force acting on the sliding plates 106A and 106B and the tape 101T when the tape winding operation is stopped is shown.

In Figure 5, the tension F is caused in the tape 101T wound on the wire 300, F 'is the drag caused in the tape 101T by friction roller 107, N _v is the surface of the wire 300 acting sliding plate 106A, the 106B , N _p represents the drag in the direction along the surface of the electric wire 300 acting on the sliding plates 106A and 106B.

  Since the tape 101T is wound around the electric wire 300 so as to have the tension F, even when the tape winding operation is stopped, the tape 101T wound around the electric wire 300 has a tension F. On the other hand, the friction roller 107 generates a drag F ′ as a frictional resistance against the tension F with respect to the tape 101T. That is, when the tape winding operation is stopped, the force acting on the tape 101T is in a state where the tension F and the drag force F 'are balanced.

  On the other hand, the posture stability of the tape winding device 100 can be understood by considering the moment acting on the tape winding device 100. As for the moment acting on the tape winding device 100, the end position where the tape 101T and the electric wire 300 are in contact is considered as the reference position of the moment (indicated as T in FIG. 5).

  At this time, the tape winding apparatus 100 is subjected to a moment to rotate around the P2 axis with respect to the moment reference position T by the tension F from the tape 101T wound around the electric wire 300.

Therefore, with the tape winding device 100, when working tape wrap, by abutting the sliding plate 106A, and 106B to wire 300, sliding plate 106A, the 106B, vertical to the surface of the wire 300 drag N _v , and reacted with drag N _p in the direction along the surface of the wire 300 holds such moments acting on the tape wrap apparatus 100 is in a state of being balanced. That is, the tape winding apparatus 100 stabilizes the posture by rotating the case 102 and the arm 106 about the longitudinal axis Q of the electric wire 300 while the sliding plates 106A and 106B are in contact with the electric wire 300. I am trying.

  Further, the sliding plates 106 </ b> A and 106 </ b> B are disposed as a pair along the longitudinal direction Q of the electric wire 300. Therefore, even when a moment around the P3 axis acts on the tape winding apparatus 100 during the tape winding operation, the posture can be stabilized.

  In this way, the moment acting on the tape winding device 100 is held in a balanced state by the sliding plates 106A and 106B. For this reason, even when the operator retakes the tape winding device 100 with the operation rod 200, the position of the tape winding device 100 is held without moving, and the tape winding operation to the electric wire 300 is easily performed. be able to.

  As mentioned above, according to the tape winding apparatus which concerns on this embodiment, since the attitude | position with respect to an electric wire can be stabilized at the time of tape winding operation | work of a self-fusing tape, work efficiency can be improved. Moreover, according to the tape winding apparatus according to the present embodiment, the tape winding apparatus can be downsized because it can be configured separately from the operation rod without using a gear mechanism.

<Other embodiments>
In the above-described embodiment, the sliding plates 106A and 106B are shown as being attached to the arm 108 so that the direction in which the sliding surface extends is parallel to the winding axis direction P2. However, the sliding plates 106A and 106B may be attached to the arm 108 so that the direction in which the sliding surface extends is inclined from the winding axis direction P2 toward the tape drawing direction P1. In this case, the tape winding apparatus 100 can be configured to slide along the outer peripheral surface of the electric wire 300 while shifting the winding position of the tape 101T in the longitudinal direction Q of the electric wire 300.

  In the above-described embodiment, the aspect in which the friction roller 107 is used so that the tape 101T is pulled out with tension is shown. However, other configurations may be used as long as a drag force is generated in the direction opposite to the force acting in the tape drawing direction P1 of the tape 101T when the tape 101T is pulled out from the wound body 101. For example, a material that generates a predetermined frictional force may be disposed between the wound body 101 and the hole 103 of the case 102 that supports the wound body 101.

  Moreover, in the said embodiment, the aspect which performs a tape winding operation | work using the operation stick 200 was shown. However, it is not always necessary to use the operation rod 200 for the tape winding work, and an operator may wear insulating gloves and rotate the tape winding apparatus 100 by hand.

  Moreover, in the said embodiment, the aspect which apply | coats an adhesive agent in the initial position which winds the tape of the electric wire 300 was shown. However, the fixing method of the initial position is arbitrary, and a method of fixing the end portion of the tape 101T drawn from the wound body 101 to the electric wire 300 using a fixing member may be used.

=== Conclusion ===
As described above, in the above-described embodiment, the wound body 101 in which the insulating self-bonding tape for covering the electric wire 300 is overlapped and wound, and the self-bonding tape is pulled out of the wound body 101 with tension. A case 102 that rotatably supports the winding body 101 and a tip portion that extends from the case 102 in a direction in which the self-bonding tape is pulled out and holds the tip of the self-bonding tape that is pulled out. When the distal end 108T is disposed adjacent to the arm 108 having the 108T and the distal end portion 108T, the arm 108 and the case 102 rotate about the longitudinal axis of the electrical wire 300, and the self Tape winding provided with sliding plates 106A and 106B that slide along the outer peripheral surface of the electric wire 300 so that the fusion tape is attached to the electric wire 300 while being pulled out. It is intended to disclose a device 100.

  As a result, for example, even when a tape-wrapping operation of a self-bonding tape is performed on an electric wire using an insulating operating rod, the posture of the wire can be stabilized and the tape winding operation can be made more efficient. A winding device can be realized. In addition, this makes it possible to reduce the size of the tape winding device.

  Here, the sliding plates 106 </ b> A and 106 </ b> B may have a sliding surface that has a shape along the electric wire 300 and opposes a half or less of the outer peripheral surfaces of the electric wire 300.

  Thereby, the stability of the posture with respect to the moment around the P2 axis to the tape winding device during the tape winding operation can be improved.

  Here, the sliding plates 106 </ b> A and 106 </ b> B may be arranged in a pair with the arm 108 sandwiched along the longitudinal direction of the electric wire 300 in a state where the tip end portion 108 </ b> T faces the electric wire 300.

  Thereby, the stability of the posture with respect to the moment around the P3 axis to the tape winding device during the tape winding operation can be improved.

  Here, the front end portion 108T may have a cutter 105 for cutting the self-bonding tape.

  Thus, when the tape winding operation is completed by the tape winding apparatus, the drawn tape can be easily cut.

  Here, the case 102 may have a hole 103 into which the tip of the insulating operation rod 200 is detachably attached.

  Thus, when the tape winding operation is performed using the insulating operation rod, the tape winding device can be easily held by the operation rod.

  Here, the hole 103 may be provided through the winding shaft of the winding body 101 so that the winding body 101 is rotatably supported.

  Thereby, the tape winding device can be further downsized.

  Here, the case 102, the arm 108, and the sliding plates 106A and 106B may be formed of an insulating material.

  Thereby, the electric leakage from an electric wire to an operator can be prevented.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 100 Tape winding apparatus 101 Winding body 101T Tape 102 Case 103 Hole 104 Delivery port 105 Cutter 106A, 106B Sliding plate 107 Friction roller 108 Arm 200 Operation rod 300 Electric wire

Claims (7)

A wound body in which a self-fusing tape having insulating properties for covering an electric wire is overlapped and wound;
A case for rotatably supporting the winding body so that the self-bonding tape is pulled out from the winding body with tension;
An arm extending from the case in a direction in which the self-bonding tape is pulled out and having a tip portion for holding the tip of the self-bonding tape being pulled out;
The arm and the case rotate around the longitudinal axis of the electric wire and the self-bonding tape is pulled out when it is arranged adjacent to the front end and the front end faces the electric wire. While being attached to the electric wire, a sliding plate that slides along the outer peripheral surface of the electric wire,
A tape winding device comprising: The tape winding device according to claim 1, wherein the sliding plate has a sliding surface that has a shape along the electric wire and faces a surface that is less than a half of the outer peripheral surface of the electric wire. 3. The slide plate according to claim 1, wherein a pair of the slide plates is arranged with the arm sandwiched along a longitudinal direction of the electric wire in a state where the tip portion faces the electric wire. Tape winding device. The tape winding device according to any one of claims 1 to 3, wherein a cutter for cutting the self-bonding tape is provided at the tip portion. The tape winding device according to any one of claims 1 to 4, wherein the case has a hole portion in which a tip of an insulating operation rod is detachably mounted. The tape winding device according to claim 5, wherein the hole portion is provided through a winding shaft of the winding body so that the winding body is rotatably supported. The tape winding apparatus according to any one of claims 1 to 6, wherein the case, the arm, and the sliding plate are formed of an insulating material.

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