JP4905520B2 - Up and down universal joint for cable rack - Google Patents

Description

  The present invention relates to a cable rack vertical joint that secures electrical connection between the cable racks, and does not use a ground bond wire, and it does not require management of the tightening torque value with a dedicated tool, etc. Related to fittings.

  Many of the metal cable racks used for wiring take into account the weather resistance, rust resistance, salt resistance, moisture resistance, chemical resistance, etc. Special surface treatments such as epoxy resin-based coating with excellent rust resistance are applied. However, since these special surface treatment films are not conductive, various proposals have been made to electrically connect the cable racks. For example, Patent Document 1 discloses a structure in which cable racks are connected to each other with a ground bond line. There is also a proposal to use a means for forcibly separating the coating of the cable rack by providing protrusions (Patent Document 2) and serrated irregularities (Patent Document 3) on the bearing surfaces of bolts and nuts. is there.

  In Patent Document 1, since the work of connecting the earth bond wire is added to the cable rack connection work, it takes a lot of labor as the connection work, and in Patent Document 2 and Patent Document 3, it is peeled into protrusions and serrated irregularities. When the coated films are overlapped, there are problems such as difficulty in further peeling and insufficient electrical connection. The present applicant has developed Patent Document 4 in order to solve such a problem, and is currently employed in many cable rack connecting works as a method of ensuring electrical connection.

  In Patent Document 4, in order to ensure electrical connection, a conductive joint bolt is provided with a square root portion that is forcedly inserted into a bolt insertion hole of a cable rack to widen the bolt insertion hole. A screw-shaped fracture protrusion is formed on the conductive nut to be screwed around to press the surface treatment film to be pressed around, and the cable racks are electrically connected to each other by the fastening means of these joint bolts and nuts. The present invention relates to a method for connecting cable racks.

  However, the joining method according to Patent Document 4 has not been approved so far for the upper and lower universal joints. For this reason, when the electrical connection is made using the vertically movable joint, it is necessary to connect the earth bond wire R to each other as shown in FIG.

Japanese Utility Model Publication No. 55-43700 Japanese Utility Model Publication No. 54-48399 Japanese Utility Model Publication No. 56-51414 Japanese Patent Publication No. 4-4808

  The cable rack splicing method disclosed in Patent Document 4 uses a square root bolt and a fixing nut with a serrate when a cable rack main girder member and a straight splicing member, or when the main girder is overlapped with each other. It is intended to connect, but recently, for the purpose of electrically connecting the overlapped joint pieces at the upper and lower universal joints, instead of the conventional connecting shaft that connects the joint pieces, the cable rack main beam member and the straight line Tighten to the specified torque using square root bolts and fixing nuts with serrations used to connect the fittings, and use square root bolts and fixing nuts with serrations as with straight fittings. Depending on the conditions, such as connecting the cable rack main beam member and the joint piece and tightening them with the specified torque value, and then applying a tightening confirmation seal near the tightening part after tightening confirmation Splicing method according to Patent Document 4 also in the vertical universal joint is authorized (Ministry of Land, Infrastructure and Transport Minister's Secretariat administration Buildings Department unit Supervision 2007 edition electrical installation work management guidelines). In this splicing method, it is extremely important to manage the tightening torque value with a dedicated tool in order to obtain a sufficient electrical connection. That is, in order to break the coating film between the upper and lower universal joints and to ensure electrical connection, it is necessary to tighten with a dedicated tool such as a torque wrench until the specified torque value is reached. If the tightening torque is insufficient, the electrical connection may be insufficient.

  Therefore, it is obliged to affix a tightening confirmation seal in the vicinity of the tightening portion as proof that the torque has been tightened to the specified torque value. However, since the operation for connecting the upper and lower universal joints is often performed at a high place, the confirmation seal alone is disadvantageous in that it is not reliable. For example, when a seal is applied in a state where the tightening torque is insufficient, it is very difficult to check at a high place even if the tightening torque is to be checked later. In some cases, it is difficult to confirm the seal at a high place.

  Moreover, the connection state using joint bolts and nuts that ensure electrical connection is almost the same as the connection state of general bolts and nuts. It is also difficult to determine whether the nut is a joint bolt or nut that can be electrically connected after coupling.

  In addition, because the up and down universal joint is used when connecting the cable rack in a bent state up and down, a reinforcement girder for supporting the cable at the bent part of the cable rack should be added to the vertical joint. There is also. In this case, the stiffener girders are connected to the joint bolts penetrating the vertically movable joint, so that the stiffener girders hinder electrical connection by the joint bolts. For this reason, when a reinforcement beam is added to the vertically movable joint, it is necessary to separately connect a ground bond line even if a joint bolt or the like that enables electrical connection is used.

  Therefore, the present invention was created to solve the above-mentioned problems, and in the connection work between the upper and lower universal joints, it becomes unnecessary to manage the tightening torque value with a dedicated tool, and the connection work is easy and uniform even at high places. It is possible to check whether or not it is electrically connected even after it is connected, and it is possible to check whether it is electrically connected. The purpose is to provide metal fittings.

In order to achieve the above-mentioned object, the first means in the present invention includes a pair of connecting pieces 10 attached to the connecting ends of the cable rack P, a joint piece 20 extended from each of the connecting pieces 10, and a cable. The coupling piece 20 is inserted into a through-hole 21 that is opened to each other when the rack P is connected, and the coupling piece 20 is coupled to the coupling piece 20 so that the vertical bending angle can be adjusted. In the up-and-down universal joint having a non-conductive surface treatment film on the surface thereof,
A fixing hole 22 through which the tapping screw 40 or the metric screw 50 is inserted from one joint piece 20 side is opened in one joint piece 20 of the superposed joint pieces 20, and one joint piece 20 is formed in the other joint piece 20. An adjustment hole 23 or an adjustment recess 24 having a long hole curved in a substantially circular arc shape for fixing the end of the tapping screw 40 or the metric screw 50 inserted through the upper part is formed, and the vertical bending angle adjustment between the superposed joint pieces 20 is adjusted. The position is fixed with the tapping screw 40 or the metric screw 50 and the joint pieces 20 are electrically connected to each other via the tapping screw 40 or the metric screw 50, and the fixing hole 22 is centered on the through hole 21 of the joint piece 20. both substantially the plural number on a concentric yen, adjusting hole 23 together are formed in a substantially arc shape on a substantially concentric circles at the center of the through-hole 21, the joint pieces 20, It features a fixed hole 22 and adjustment holes 23 or adjustment recess 24 lies in the provision to allow insertion of the tapping screw 40 or metric thread 50 from either polymerized joint pieces 20 of the other.

The diameter of the fixing hole 22 and the width of the adjustment hole 23 in the second means are formed to be smaller and narrower than the screw diameter of the tapping screw 40.

The width of the adjusting hole 23 of the third means is formed narrower than the screw diameter of the tapping screw 40, the diameter of the fixing hole 22 is formed larger than the screw diameter of the tapping screw 40, and A protrusion 41 is provided on the lower surface of the head 42 of the tapping screw 40 so as to be recessed from the outer surface around the fixing hole 22.

The fourth means is a position where the fixing hole 22 and the adjustment hole 23 do not interfere with the reinforcing beam Q when the reinforcing beam G attached to the connecting portion of the cable rack P is connected to the connecting shaft 30. In order to polymerize.

According to a fifth means, in the vertically movable joint, the fixing hole 22 has a smaller diameter than the tapping screw 40 and has a substantially oval shape formed so that the tapping screw 40 is bitten. An adjustment concave portion 24 having a substantially circular arc shape that presses the tip of the tapping screw 40 inserted from the piece 20 is provided, and the vertical bending angle adjustment position between the overlapped joint pieces 20 is fixed by the tapping screw 40, and the tapping screw 40 The joint piece 20 is provided so as to be electrically connected to each other through the joint.

The sixth means is that in the vertically movable joint, the fixing hole 22 is tapped so as to screw the metric screw 50, and the tip of the metric screw 50 inserted into the other joint piece 20 from the one joint piece 20 is used. An adjustment recess 24 having a substantially circular arc shape to be pressed is provided, and the vertical bending angle adjustment position of the overlapped joint pieces 20 is fixed with a metric screw 50, and the joint pieces 20 are electrically connected to each other via the metric screw 50. It is in providing to connect.

The fixing hole 22 in the seventh means is formed by tapping an insertion hole opened in the joint piece 20 by burring.

The eighth means is that in the above-mentioned universal joint, the fixing hole 22 has a substantially oval shape which is smaller than the screw diameter of the tapping screw 40 and is formed to bite the thread of the tapping screw 40, and the other joint. The part 20 is formed with a long hole-like adjustment hole 23 that is curved in a substantially circular arc shape through which the end of the tapping screw 40 inserted from one joint piece 20 is inserted, and the fixing hole 22 or the adjustment hole 23 is formed. The plate thickness is made thin.

  As in claim 1 of the present invention, the fixing hole 22 through which the tapping screw 40 or the metric screw 50 is inserted from one side of the joint piece 20 is opened in one joint piece 20 of the superposed joint pieces 20, and the other Since the adjustment hole 23 having a long hole for fixing the tapping screw 40 or the metric screw 50 inserted from one of the joint pieces 20 is opened in the joint piece 20, the vertical joints of the vertical joints can be moved vertically. The tapping screw 40 or the metric screw 50 fixes the bending angle adjustment position, and the electrical connection between the joint pieces 20 can be reliably performed. As a result, it is not necessary to manage the tightening torque value with a dedicated tool, and the electrical connection can be made uniform with a simple connecting operation even at a high place. In addition, it is possible to surely confirm whether or not it is electrically connected only by confirming the attachment state of the tapping screw 40 or the metric screw 50.

Further , since the fixing hole 22 and the adjustment hole 23 are formed on the concentric circle with the through hole 21 as the center, the tapping screw 40 can be inserted along the vertical bending angle between the overlapped joint pieces 20. The fixing work of the joint piece 20 can be facilitated.

  In addition, by providing the tapping screw 40 so that it can be inserted from either of the joint pieces 20, the angle adjustment work, the fixing work, and the like become easier.

Furthermore, as shown in claim 2, the fixing hole 22 and the adjustment hole 23 are formed to have a diameter smaller than the screw diameter of the tapping screw 40, whereby the fixing by the tapping screw 40 and the electrical connection can be ensured.

Further, as described in claim 3 , fixing by the tapping screw 40 and electrical connection can also be achieved by providing a protrusion 41 that is not easily provided on the outer surface around the fixing hole 22 on the lower surface of the head 42 of the tapping screw 40.

Even when the reinforcement beam Q is connected to the connection portion of the cable rack P as in claim 4 , the fixing hole 22 and the adjustment hole 23 overlap at a position where they do not interfere with the reinforcement beam Q. The joint pieces 20 can be electrically connected by being inserted. As a result, it is not necessary to separately connect a ground bond line even when the reinforcement beam Q is added.

In claim 5 , the fixing hole 22 is formed in a substantially plane shape and has a smaller diameter than the tapping screw 40, and the tapping screw 40 is inserted into the other coupling piece 20 from the one coupling piece 20. Since the adjustment concave portion 24 that presses the tip of the steel plate is provided, the surface treatment film of the adjustment concave portion 24 is scraped off while being bitten into the iron base by tightening the tapping screw 40, so that fixing with the tapping screw 40 and electrical connection are possible. become.

According to the sixth and seventh aspects, since the fixing hole 22 is tapped so as to screw the metric screw 50, the vertical bending angle adjustment position between the overlapped joint pieces 20 can also be fixed by the metric screw 50. It is something that can be done.

According to the eighth aspect , by forming a thin plate at the portion where the fixing hole 22 or the adjustment hole 23 is formed, the tapping screw 40 can be easily tightened even when a hard material such as stainless steel or the plate is thick. can do.

It is a front view of the use condition which shows one Example of this invention. It is a top sectional view of the use condition which shows one Example of this invention. It is a front view which shows one Example of the connection piece and joint piece of this invention. It is a front view which shows one Example of the through-hole and adjustment hole of this invention. It is principal part sectional drawing which shows one Example of the fixing hole and adjustment hole of this invention. It is a perspective view which shows the state which mounted | wore the reinforcement beam in one Example of this invention. The other Example of the coupling piece of this invention is shown, (A) is a front view (B) is sectional drawing. It is principal part sectional drawing which shows one Example of the fixing hole and adjustment recessed part of this invention. It is principal part sectional drawing which shows the other Example of the fixing hole and adjustment recessed part of this invention. It is principal part sectional drawing which shows the other Example of the fixing hole and adjustment recessed part of this invention. It is principal part sectional drawing which shows the other Example of the fixing hole and adjustment recessed part of this invention. It is principal part sectional drawing which shows the other Example of the fixing hole and adjustment hole of this invention. It is a perspective view which shows the splicing method by the conventional vertical joint.

  According to the present invention, it is not necessary to manage the tightening torque value with a dedicated tool, and the connection work is easy and uniform even at high places, and it is possible to confirm whether or not the connection is made even after connection. It was possible to achieve various effects such as eliminating the need for a separate earth bond line even when additional reinforcement girders were added.

  The vertically movable joint of the present invention is a joint for connecting the cable racks P in a conductive state. That is, a vertical joint with a non-conductive surface treatment film is attached to the connection ends of the metal cable rack P with a non-conductive surface treatment film so that the cable racks P are moved up and down. In particular, it is configured to be connected flexibly, and in particular, it is configured to be electrically connected by a tapping screw 40 while the vertically movable joint itself is fixed to be vertically bent.

  In the vertical joint shown in FIGS. 1 to 6, an embodiment is shown in which a circular fixing hole 22 and an elongated adjustment hole 23 curved in a substantially circular arc shape are combined. That is, the configuration of the vertically movable joint of the present invention includes a connecting piece 10 having a non-conductive surface treatment film on its surface, a joint piece 20, and a connecting shaft 30 for connecting the joint pieces 20 to each other (FIG. 1). reference). The connecting piece 10 is a pair of members attached to the connecting ends of the cable rack P, and the joint piece 20 is extended from the connecting piece 10. The joint piece 20 is a member that is polymerized when the cable rack P is connected, and a through hole 21 is opened between the joint pieces 20 (see FIG. 3). The connecting shaft 30 is inserted through the through hole 21 and connects the joint pieces 20 so that the vertical bending angle can be adjusted. In the illustrated example, a connecting bolt 30A and a nut 30B are used as the connecting shaft 30 ( (See FIG. 1). Thus, by connecting the joint pieces 20 so that the vertical bending angle can be adjusted, the connecting end portions of the cable rack P are connected so that the vertical bending angle can be adjusted.

  A fixing hole 22 is opened in one joint piece 20 between the superposed joint pieces 20 (see FIG. 1). The fixing hole 22 allows the tapping screw 40 to be inserted from the one coupling piece 20 side toward the other coupling piece 20, and the head portion 42 of the tapping screw 40 comes into contact with the one coupling piece 20. The illustrated fixing hole 22 is formed in plural on a concentric circle centering on the through hole 21 of the joint piece 20 (see FIGS. 1 and 3). The shape of the fixing hole 22 can be arbitrarily formed such as a round hole shape or a square hole shape. For example, the fixing hole 22 can be formed in a substantially arc shape on a concentric circle with the through hole 21 as the center ( (Refer to Drawing 4 (I)-(C)).

  An adjustment hole 23 is opened in the other joint piece 20 between the superposed joint pieces 20 (see FIG. 1). The adjustment hole 23 is a long hole through which the tapping screw 40 inserted from one joint piece 20 is inserted, and is formed in a substantially arc shape on a concentric circle with the through hole 21 as the center. The adjustment hole 23 is inserted and fixed with the tapping screw 40, and the width of the adjustment hole 23 is narrower than the screw diameter of the tapping screw 40 in order to electrically connect the joint pieces 20 to each other. . In the illustrated example, together with the adjustment hole 23, the diameter of the fixing hole 22 is smaller than the screw diameter of the tapping screw 40 (see FIG. 5 (a)). Further, the diameter of the fixing hole 22 may be formed larger than the screw diameter of the tapping screw 40 (see (b) in the same figure). In this case, a protrusion 41 that is hard to be formed on the outer surface around the fixing hole 22 is provided on the lower surface of the head 42 of the tapping screw 40, and the non-conductive surface treatment film applied to the surface of the joint piece 20 is removed by the protrusion 41. The pieces 20 are electrically connected to each other.

  In this way, by inserting the tapping screw 40 from the fixing hole 22 of one joint piece 20 and fixing the tapping screw 40 to the adjusting hole 23 of the other joint piece 20, the vertical bending adjustment position between the joint pieces 20 is fixed. In addition, the joint pieces 20 are electrically connected to each other. At this time, the fixing hole 22 and the adjustment hole 23 are provided in both the joint pieces 20 so that the tapping screw 40 can be inserted from either of the superposed joint pieces 20 (FIGS. 1 and 2). 2). Moreover, the connection accuracy of the cable rack P is improved by bending the base end portion of one of the joint pieces 20 and forming the positions so that the positions of the cable racks P to which the connection pieces 10 are fixed are connected to each other on a straight line. (See FIG. 2).

  The vertical joint of the present invention is used when the cable rack P is connected in a state of being bent up and down. For this reason, a reinforcement beam Q for supporting the cable at the connecting portion of the cable rack P may be added. In this case, the stiffener girders Q are installed inside the overlapped joint pieces 20 and attached to the connecting shafts 30 that pass through the through holes 21 of the joint pieces 20 (see FIG. 6). At this time, the fixing hole 22 and the adjustment hole 23 are formed in the joint piece 20 so as to be superposed at a position where they do not interfere with the reinforcement beam Q.

  For the electrical connection between the connecting piece 10 attached to the cable rack P and the cable rack P, a conventional square root bolt 1 and a fixing nut 2 with a serrate 3 are used. That is, the square root bolts 1 are inserted from the inside of the cable rack P and passed through the connection holes 11 of the connection pieces 10 disposed on the outside of the cable rack P to tighten the fixing nut 2 (see FIGS. 3 and 6). Then, the surface treatment film on the cable rack P side is broken by the square root portion of the square root bolt 1 (see FIG. 2). On the other hand, since the serrated 3 of the fixing nut 2 pushes the surface treatment film of the connecting piece 10 around and peels off, the cable rack P and the connecting piece 10 are electrically connected.

FIG. 6 shows a state where aluminum type cable racks P are connected. Further, as shown in the conventional example of FIG. 13, when the cable rack P is a steel type, the shape of the connecting piece 10 in the joint of the present invention is also changed to the same shape as the connecting piece 100 of the conventional joint. However, even in this case, the joint piece 20 is not the conventional joint piece 200, but instead of FIGS.
As shown in FIG. 6, the joint piece 20 of the present invention having the fixing hole 22 and the adjustment hole 23 is obtained.

  7 and 8 show an embodiment in which a substantially oval shaped fixing hole 22 and an adjustment recess 24 are combined. That is, the fixing hole 22 of the vertically movable joint is formed in a flat oval shape formed by a long hole having a diameter slightly smaller than the diameter of the tapping screw 40 (see FIG. 7 (A)).

  On the other hand, the adjustment concave portion 24 of the vertically movable joint is formed by providing a flat substantially arc-shaped adjustment concave portion 24 that presses the tip of a tapping screw 40 inserted through one joint piece 20. The adjustment recess 24 has an opening that is curved in a substantially circular arc shape similar to the shape of the adjustment hole 23 (see FIG. 7A). For example, the joint piece 20 is punched out to form a recess. (See (b) in the figure).

  When the tapping screw 40 is tightened on such a vertical joint (see FIG. 8 (a)), the tip of the tapping screw 40 is adjusted to the adjustment recess while the thread of the tapping screw 40 bites into the iron base of the opening portion of the fixing hole 22. The surface inside the 24 recesses is scraped to obtain an electrical connection (see (b) in the figure).

  The vertical joint shown in FIGS. 9 to 11 shows an embodiment in which a round hole-shaped fixing hole 22 that has been tapped and the adjustment recess 24 are combined. In this embodiment, a normal metric screw 50 can be used.

  That is, the fixing hole 22 shown in FIG. 9 is obtained by opening the joint piece 20 in a round hole shape and processing the tap 22A in this opening portion. Further, the fixing hole 22 shown in FIG. 10 is obtained by applying a burring process to the joint piece 20 so as to protrude in the direction opposite to the adjustment recess 24, and providing a tap 22A on the inner peripheral surface. Furthermore, the fixing hole 22 shown in FIG. 11 is a burring projecting in the direction of the adjustment recess 24, and a tap 22A is applied to the inner peripheral surface. According to such a fixing hole 22, a normal metric screw 50 can be used.

  The upper and lower universal joint shown in FIG. 12 shows an embodiment in which a fixed hole 22 and an adjustment hole 23 having a substantially plane shape are combined. In this embodiment, a tapping screw 40 is used. That is, the diameter of the fixing hole 22 and the width of the adjustment hole 23 are formed to be slightly smaller and narrower than the screw diameter of the tapping screw 40, and the thickness of the portion where the fixing hole 22 or the adjustment hole 23 is formed is thin. Formed.

  FIG. 12A shows that the tapping screw 40 is screwed into a thin plate around the fixing hole 22. Further, as shown in FIG. 5B, the plate thickness around the adjustment hole 23 can be made thin. Such a vertically movable joint can facilitate the screwing operation of the tapping screw 40 even when the tapping screw 40 is difficult to enter, such as when the material is hard such as stainless steel or the plate is thick.

  The present invention is applicable to all forms of cable racks P. Further, the present invention is not limited to the illustrated example, and the shape and structure of the fitting, the shape of the fixing hole 22 and the adjusting hole 23, the shape of the adjusting recess 24, the substitute for the tapping screw 40 and the metric screw 50, etc. As long as the gist of the invention is not changed, it can be freely changed.

P Cable rack P1 Connection hole Q Reinforcement girder R Ground bond wire 1 Square root bolt 2 Fixing nut 3 Serite 10 Connection piece 11 Connection hole 20 Joint piece 21 Through hole 22 Fixing hole 22A Tap 23 Adjustment hole 24 Adjustment recess 30 Connection shaft 40 Tapping screw 41 Protrusion 42 Head 50 Metric screw 100 Connecting piece 200 Joint piece

Claims (8)

A pair of connecting pieces attached to the connecting ends of the cable rack, joint pieces extended from the connecting pieces, and through-holes opened between the joint pieces superposed at the time of connecting the cable rack In a vertically movable joint comprising a connecting shaft that connects the joint pieces to each other so that the vertical bending angle can be adjusted, and a non-conductive surface treatment film is applied to the surfaces of the connecting pieces and the joint pieces.
A fixing hole through which a tapping screw or metric screw is inserted from one joint piece side is opened in one joint piece of the superposed joint pieces, and a tapping screw or metric screw inserted from one joint piece into the other joint piece. A long hole-like adjustment hole or adjustment concave portion curved in a substantially circular arc shape for fixing the end portion is formed, and the vertical bending angle adjustment position between the overlapped joint pieces is fixed with a tapping screw or a metric screw, and the tapping screw or Provided to connect the joint pieces electrically via metric screws,
A plurality of fixing holes are formed on a substantially concentric circle centered on the through-hole of the joint piece, and the adjustment holes are formed in a substantially arc shape on a substantially concentric circle centered on the through-hole ,
A vertical joint for cable racks, characterized in that both joint pieces are provided with a fixing hole and an adjustment hole or adjustment recess so that a tapping screw or a metric screw can be inserted from either of the superposed joint pieces. Hardware.   2. The vertically movable joint for a cable rack according to claim 1, wherein a diameter of the fixing hole and a width of the adjusting hole are formed to be smaller and narrower than a screw diameter of the tapping screw.   The width of the adjustment hole is narrower than the screw diameter of the tapping screw, the diameter of the fixing hole is larger than the screw diameter of the tapping screw, and the outer surface around the fixing hole is not easily inserted. The vertically movable joint for a cable rack according to claim 1, wherein a protrusion is provided on a lower surface of the head of the tapping screw. 2. The device according to claim 1, wherein the fixing hole and the adjustment hole are overlapped at a position where they do not interfere with the reinforcing bar when the reinforcing bar is attached to the connecting portion of the cable rack. 3. A vertically movable joint for a cable rack according to any one of 3 above.   In the upper and lower universal joint, the fixing hole has a smaller diameter than the tapping screw and is formed in a substantially oval shape so that the tapping screw can be bite in. An adjustment recess having a substantially arcuate flat shape is provided, and the vertical bending angle adjustment position of the overlapped joint pieces is fixed with a tapping screw, and the fitting pieces are electrically connected to each other via the tapping screw. The vertically movable joint for a cable rack according to claim 1.   In the vertical joint, the fixing hole is tapped so that a metric screw is screwed in, and a flat, substantially arc-shaped adjustment concave portion that presses the tip of the metric screw inserted from one joint piece into the other joint piece is recessed. 2. The cable rack according to claim 1, wherein the vertical bending angle adjustment position of the overlapped joint pieces is fixed with a metric screw, and the joint pieces are electrically connected to each other via the metric screw. Vertical joint. 7. The vertically movable joint for a cable rack according to claim 6 , wherein the fixing hole is formed by tapping an insertion hole opened by burring in the joint piece.   In the vertically movable joint, the fixing hole is smaller than the screw diameter of the tapping screw and has a substantially oval shape formed so as to bite the thread of the tapping screw, and is inserted into the other joint piece from one joint piece. 2. The cable rack according to claim 1, wherein a long hole-like adjustment hole curved in a substantially arcuate plane shape through which an end of the tapping screw is inserted is formed, and a thickness of a portion where the fixing hole or the adjustment hole is formed is reduced. Vertical joint.

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