JP2007207590A - Earth terminal receiving jig - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earth terminal receiving jig capable of simply applying countermeasure against current leakage to an electric heater of industrial use at low cost. <P>SOLUTION: On the band-shaped electric heater of industrial use, a nut part 10 having an inner diameter conforming to a fastening screw 8, and a unit of earth terminal receiving jig 9 integrated with the nut part 10, consisted of a bolt part 11 having a diameter in which a mounting hole of the earth terminal 13 can be inserted, are screwed into a top end part of the fastening screw 8 having a temperature lower than that of the electric heater main body. By the above, it is constituted so as to be able to attach the earth terminal 13 to the band-shaped electric heater of industrial use easily. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a grounding terminal receiving jig that can be retrofitted to a nozzle heater or the like provided around a resin molding machine or an extruder.

  Band heaters can be used in a wide range of applications, including cylinder heating for plastic molding machines such as resin molding machines and extrusion machines, and cylinder heating for pipelines, as well as various heating equipment, hot air generators, dryers, pipes and hoppers, etc. It is an electric heating element suitable for close contact heating having a thin cylindrical structure by mica insulation. As a general structure of the band heater 100, as shown in FIG. 6, a structure in which the heating wire 102 is insulated by a mica plate 101 having high heat resistance and is further packaged by a metal case 103 is general. In this structure, a fastening fitting 105 provided on the metal case 103 is used in order to bring the band heater into close contact with the object to be heated. The fastening fitting 105 is composed of two parts, each having a hole through which a screw is inserted. One of the holes has a straight structure having a slightly larger diameter than the bolt portion of the tightening screw 106, and the other hole is a nut into which the bolt portion of the tightening screw head 106a of the tightening screw 106 is screwed. It has a structure. When the fastening screw 106 is continuously inserted from the fastening member 105 on the straight structure side, the fastening member 105 comes into contact with and is locked with the fastening member 105 having a nut structure. Here, for example, using a screwdriver or the like that matches the shape of the screw head 106 a of the tightening screw 106, the tightening screw 106 is screwed into a nut portion formed inside the tightening fitting 105 by rotating in the clockwise direction. The band heater 100 is lightweight, has high shape adaptability, has a smooth contact surface, can ensure good contact, and has high thermal conductivity and high heating effects, so it can be widely used in industrial fields other than resin molding machines and extruders. It has been broken.

  On the other hand, when looking at safety, the band heater alone used in conventional resin molding machines and extruders did not need to be connected to the ground, but it was not that safety problems were not recognized. . However, in recent years, a molding resin having a high melting temperature has been used, and the operating temperature of the heater tends to be high. The band heater has a problem that when the operating temperature is high, the metal plate is stretched greatly, a gap is formed between the heated object, the heater and the heated object are not in close contact, and a local heat portion is likely to occur. In order to reduce the effects of local heat, regular tightening became an important task. If local heat is generated, disconnection due to overheating is likely to occur at the local heat location, and there is a risk that at the time of disconnection, a failure such as a decrease in insulation or breakdown of the insulating material may lead to leakage.

  On the other hand, in overseas markets such as Europe, there is a movement to require the grounding of the band heater alone. For example, IEC 61558, which is being developed since 1997, defines safety standards related to transformers, and is also trying to standardize measurement methods for ground terminals and leakage.

  When the grounding terminal is installed on the band heater body, the effective area of the heat generating part is reduced, and when trying to secure the wattage of the entire device, the watt density of the heater part becomes high and temperature spots are generated. Also cause disconnection. In addition, the shape of the ground terminal is different from the shape of the power supply terminal of the heater, and troubles will occur unless the worker can easily recognize the shape.

  In addition, when the ground terminal is provided on the mounting band, it is difficult to design the band surface without unevenness, and in terms of cost, it is necessary to accept the unevenness. Tightening becomes difficult. In addition, since the ground terminal is formed on the heater surface, there is a risk that the temperature may be partially increased and local heat is easily generated, and the ground wire may be damaged.

  Since there is a safety problem if the band heater is not grounded as described above, the heat of the band heater propagates when trying to connect the ground terminal to a band heater without an existing ground terminal. In some cases, taking too much time is dangerous. Therefore, for example, in Patent Document 1, a shaft body portion that is inserted into the mounting hole of the ground terminal and an upper end of the shaft body portion that are larger in diameter than the shaft body portion and larger than the diameter of the mounting hole. There is also known a ground terminal receiving jig for supporting a ground terminal having a mounting hole, which is provided with a spherical body portion having a small diameter for preventing the slipping. For example, a method of attaching the ground terminal receiving jig as a ground terminal to a tightening screw of a heater band is conceivable.

Further, in Patent Document 2, a flange is fixed on a fixing segment, and a shoulder having a polygonal offset surface on the fixing segment, a segment with a pattern, and a truncated cone end segment tapered inward are arranged in this order. There is known an electrical connection structure in which a ground terminal segment with a pattern is inserted into a stud having the above structure under a polygonal eyelet and is screwed with a nut having an enlarged portion and a reduced portion from above. Similarly to the above, a method of attaching the electrical connection structure as a ground terminal to a fastening screw of the heater band is also conceivable.
Japanese Patent No. 3237494 Special table 2004-519817

  In the above, Patent Document 1 has a structure in which the ground terminal can be easily attached and detached. However, in the industrial electric heater, it is not necessary to remove the ground terminal once attached, and the ground terminal is fixed to the spherical body portion. Since there is no means, the structure is easy to come off and there is a problem in safety.

  In Patent Document 2, a dovetail having a polygonal opening shape is screwed with a nut having an enlarged portion and a reduced portion. However, in an earth terminal receiving jig for fastening an industrial heater with a metal band, the original fastening is used. Since the screws cannot be used, it is necessary to replace the metal band fastening screws themselves, which is expensive and troublesome.

  As described above, the problems that cannot be solved by Patent Documents 1 and 2 are ground terminals without stopping the operation of the production line in industrial electric heaters used in resin molding machines and extrusion machines that are continuously operated in factories and the like. It is to provide a means for easily mounting.

  In order to enable the ground terminal to be attached without stopping the operation of the production line using the heater, the present invention is configured by tightening the bolt portion inserted through the mounting hole of the ground terminal and the electric heater body. The nut part screwed into the tip of the tightening bolt of the metal band has an integrated structure, and the nut part has a polygonal shape that can be restrained by a pliers or the like, and is inserted through at least the mounting hole of the ground terminal. And the bolt portion of the metal band that fastens the electric heater body are electrically connected in a screwed state.

  In addition, the electric heater was a thin band heater in which the heating wire was insulated with heat-resistant mica, and was tightly attached to the outside of the cylindrical object to be heated covered with a metal plate with a metal band and heated.

  Furthermore, as the electric heater, a sheathed heater was cast in a metal having good thermal conductivity, and the heater and the casting were integrated.

  Further, in the cast heater, the bolt portion that is grounded is screwed to a bolt tip that is passed through a hole penetrating the coupling means of the cast heater body.

  Since the earth terminal receiving jig of the present invention is not a heater body which is a heating element in a resin molding machine or an extruder, a bolt inserted into the mounting hole of the earth terminal having heat dissipation and lower temperature than the heater body And a nut portion that is screwed onto the tip of a fastening bolt of a metal band that fastens an electric heater body such as a band heater. In the state where these are screwed, the bolt portion connected to the ground and the tip of the fastening bolt are electrically connected. Therefore, even when the electric heater is energized, once the fastening bolt is loosened, the metal band The earth terminal receiving jig can be easily attached by bringing the earth terminal receiving jig into contact with the tip of the tightening bolt and further screwing it.

  In addition, since the temperature of the grounding terminal receiving jig is inevitably lower than that of the electric heater main body, deterioration due to heat of the insulating tube used for the grounding terminal is relatively difficult to proceed. In comparison with the above, the insulation tube and the connection cable have a longer life, and a reduction in maintenance cost can be expected.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. In the following description, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

  FIG. 1 shows a band heater body 1 to which a ground terminal receiving jig 9 according to the present invention is attached. The heater unit 2 including a heating wire wound on a heated object such as a resin molding machine or an extruder is fastened with a metal band 3 to efficiently conduct heat generated by the heater to the heated object. Yes. In order to make an electrical connection from each heater unit 2, an electrode terminal 5 is provided, and the other end is interconnected by a connection terminal 6 to form a series connection configuration.

  As described above, the metal band 3 is wound from above the heater unit 2 that is in close contact with the exterior of an object to be heated such as a pipe, and is further opened in the fastening fitting (straight hole) 7a and the fastening fitting (spiral tap hole) 7b. The metal band 3 can be tightened so that the heater unit 2 can be brought into uniform contact with the object to be heated with an appropriate contact pressure while the tightening screw 8 is inserted into the through hole and screwed into the tap of the tightening fitting (spiral tap hole) 7b. ing.

  By screwing the tightening screw head 8 a of the screw 8 and the nut portion 10 of the ground terminal receiving jig 9, the metal band 3 having the same potential as the heater unit 2 can be electrically connected to the ground terminal 13.

  Although the temperature of the ground wire 13a connected to the ground terminal 13 does not rise as high as that of the heater unit 2, there is a possibility that the temperature is 400 to 500 ° C at the maximum, so that the heat resistant temperature is 400 ° C from the viewpoint of ensuring the safety of the operator. It is desirable to use a cable having the above protective coating.

  2A and 2B are views of the ground terminal receiving jig 9 with the ground terminal fixing nut 12 and the ground terminal 13 removed, wherein FIG. 2A is a front view and FIG. 2B is a plan view. The nut portion 10 and the bolt portion 11 are structurally configured, and the inner diameter of the nut portion 10 is larger than the outer diameter of the bolt portion 11. At least the base bottom portion of the nut portion 10 and the bolt portion 11 are electrically connected. If it is the structure which has continuity conduction, the base end bottom part of the nut part 10 and the bolt part 11 do not need to be an integral structure.

  As a function of the nut portion 10, it is necessary to hold the nut portion 10 with pliers or pliers so that the nut portion 10 b is not idle when the screw thread portion 8 b inserted while rotating into the inner diameter portion 14 of the nut is screwed. Therefore, as long as this object can be achieved, the outer shape is not limited to a rectangular column, and may be a polygon that is symmetric with respect to the axis of the fastening screw at the time of screwing, or may not be symmetric with respect to the axis. .

  FIG. 3 is a view showing the earth terminal receiving jig 9 to which the earth terminal fixing nut 12 and the earth terminal 13 are attached. When assembling, first, the washer 13c is inserted into the shaft of the bolt part 11, and the perforated terminal 13b is inserted thereon, and then the ground terminal fixing nut 12 is screwed together to connect the washer 13c and the perforated terminal 13b. Fix it.

  In the above, the washer 13c and the perforated terminal 13b are fixed by the ground terminal fixing nut 12. However, as long as the ground terminal 13 and the bolt part 11 are electrically connected, the ground terminal rotates. It may be free.

  Since the bolt part 11 has a heat dissipation function structurally, the tip of the bolt is maintained at a temperature lower than the operating temperature of the band heater body 1, but may still be heated up to 400 to 500 ° C. Therefore, as a safety measure for the worker, it is desirable to use a wire covered with glass fiber, silica wire or the like as the ground wire 13a of the ground terminal 13.

  In the above description, the bolt part 11 and the nut part 10 must be at least electrically connected to each other. However, since the bolt part 11 and the nut part 10 are not necessarily integrally molded products, for example, the bolt 11 is screwed onto a part of the nut part 10. It is also conceivable to form another nut hole that can be formed and to have a physical and electrical connection by screwing one end of the bolt portion 11 into the nut hole.

  Further, regarding the inner diameter portion 14 of the nut and the screw thread 15 of the nut, the inner diameter portion 14 of the nut can ensure electrical connection between the screw thread portion 8b and the bolt portion 11 which are screwed into the nut. For example, the nut portion 11 does not necessarily need to be made of metal. For example, it is conceivable to provide an electrical connection between the inner diameter portion 14 of the nut or a part of the screw thread 15 of the nut and the bolt portion 11.

  Furthermore, as an example of application of the present invention, the earth terminal receiving jig of the present invention can be used in a plate-shaped casting heater as long as the object to be heated is not cylindrical but has a built-in heater. Is valid.

  Fig.4 (a) is a figure which shows the internal structure of the band heater unit in this invention. When assembling, first, the core mica plate 16 is wrapped around the upper mica plate 18 and the lower mica plate 19 from above and below with the charging heat wire 17 wound around the core mica plate 16. (First processing) Thereby, it is possible to provide insulation without greatly degrading the thermal conductivity. In this state, it puts in the outer case steel plate 20 in which the 1st bending part 20a was formed, and also metal-bands it on the upper cover steel plate 21 (2nd process).

  FIG. 4B shows a sectional view of the heater unit 2. After the first processing, both edge portions of the first bent portion 20a of the formed outer case steel plate 20 are bent inward at a substantially right angle so as to face each other, and the upper cover steel plate 21 is suppressed from above by the second bent portion 20b. As a result, the core mica 16 wound with the charging heat wire 17 sandwiched between the upper mica plate 18 and the lower mica plate 19 is fixed inside the outer case steel plate 20 (third process).

  In the above, if there is no problem in heat resistance and electrical insulation in the operating temperature range of the heater unit 2, there is no need to stick to the upper mica plate 18 and the lower mica plate 19, and in the first processing, there is heat resistant insulation. It is also conceivable to wind the core mica plate 16 around which the charging heat wire 17 is wound with a sheet like a wrapping bag.

  In addition to the method of wrapping the upper cover steel plate 21 in the outer case steel plate 20 processed into a U shape in the second processing and the third processing, for example, it corresponds to the specification standard of electric heaters such as conductive engineering plastics. A method of molding with a resin having high heat resistance and high thermal conductivity is also conceivable.

  FIG. 5 shows another embodiment of the present invention, in which a heating element is installed in a metal pipe, and an electric heating unit 23 such as a sheathed heater having a structure in which the heating element and the metal pipe are safely insulated by an insulating powder. It is a cast-in heater that is cast and integrated into an excellent material.

  In the cast heater, the end portions of the heater wires of the electric heating unit 23 cast in the cast heater assembly 22 made of aluminum, cast iron, brass or the like selected based on the application and use temperature are collected by a connector 24. The electric heating unit 23 is connected to an external electric circuit through connector terminals 24a and 24b constituting the connector 24. Compared to band heaters, cast heaters can be cast together with cooling pipes because the heat distribution is uniform, but the entire housing is made of metal, so there is a high risk of electric leakage inside.

  The two electric heating units 23 are coupled to each other by inserting the tightening screw 8 into the bolt insertion holes provided in the two upper and lower coupling portions 25 and attaching a nut to the tip of the bolt. Among the two bolts used in the two sets of coupling portions 25, the nut portion 10 of the ground terminal receiving jig 9 is attached to at least one bolt tip portion. First, a washer 13c and then a perforated terminal 13b are inserted into the bolt part 11 connected to the nut part 10, and a grounding terminal fixing nut part 12 is screwed onto the bolt part 11 so that the grounding terminal 13 and the grounding terminal 13b are cast. The built-in heater assembly 22 is electrically connected.

  In addition to being able to install a grounding terminal on the current band heater production line without significant changes to the work procedure, it is possible to use it for industrial electric heaters such as band heaters already on the market and used in production lines. Since it is possible to attach the ground terminal without interrupting the use, it is possible to easily take measures against leakage of the production line, and to attach to the tip of the mounting bolt having a temperature lower than that of the industrial electric heater body. Therefore, the insulation tube that protects the ground wire lasts longer, reducing maintenance costs.

Band heater equipped with earth terminal receiving jig according to the present invention The figure which shows the nut part and volt | bolt part of the earthing terminal receiving jig before an assembly, (a) is a front view, (b) is a top view It is a figure which shows the earth terminal receiving jig after an assembly, (a) is a front view, (b) is a top view It is a band heater unit diagram suitable for the present invention, (a) is a structural diagram, (b) is a sectional view Example of cast-in heater equipped with earth terminal receiving jig according to the present invention Appearance and internal structure of conventional band heater

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Band heater main body, 2 ... Heater unit, 3 ... Metal band, 4 ... Safety insulator, 5 ... Electrode terminal, 6 ... Connection terminal, 7a ... Fastening metal fitting (straight hole), 7b ... Fastening metal fitting (spiral tap hole), DESCRIPTION OF SYMBOLS 8 ... Fastening screw, 8a ... Fastening screw head, 8b ... Screw thread part, 9 ... Ground terminal receiving jig, 10 ... Nut part, 11 ... Bolt part, 12 ... Ground terminal fixing nut, 13 ... Ground terminal, 13a ... Ground wire, 13b ... perforated terminal, 13c ... washer, 14 ... inner diameter of nut, 15 ... nut thread, 16 ... core mica plate, 17 ... charged hot wire, 18 ... upper mica plate, 19 ... lower mica plate, DESCRIPTION OF SYMBOLS 20 ... Outer case steel plate, 20a ... 1st bending part, 20b ... 2nd bending part, 21 ... Upper lid steel plate, 22 ... Casting heater assembly, 23 ... Electric heating unit, 24 ... Connector, 24a, 24 DESCRIPTION OF SYMBOLS ... Connector terminal, 25 ... Connection part, 100 ... Band heater, 101 ... Mica board, 102 ... Heating wire, 103 ... Metal case, 104 ... Metal band, 105 ... Fastening metal fitting, 106 ... Fastening screw, 106a ... Fastening screw head, 106b... Tightening screw tip.

Claims (4)

A ground terminal receiving jig for supporting a ground terminal having a mounting hole, wherein a bolt portion inserted through the mounting hole of the ground terminal and a tightening bolt end of a metal band for tightening a case containing an electric heater are screwed. The nut part to be fitted has an integrated structure, and the nut part has a polygonal shape whose outer periphery can be restrained by a pliers, etc., and at least the bolt part inserted through the mounting hole of the ground terminal and the electric heater body A grounding terminal receiving jig characterized in that it is electrically connected in a state where a fastening bolt tip of a metal band being fastened is screwed. 2. The earthing terminal receiving jig according to claim 1, wherein the case containing the electric heater is insulated with a metal band on the outside of a cylindrical object to be heated which is insulated with a heat resistant mica and covered with a metal plate. An earth terminal receiving jig characterized by being a thin band heater that heats in close contact. 2. The earth terminal receiving jig according to claim 1, wherein the case containing the electric heater is a cast heater in which a sheathed heater is cast in a metal having good thermal conductivity, and the heater and the casting are integrated. A grounding terminal receiving jig. A grounding terminal receiving jig for supporting a grounding terminal having a mounting hole, which constitutes a part of a casting heater body in which a bolt portion inserted into the mounting hole of the grounding terminal and an electric heater and a casting are integrated. The nut portion screwed into the tip of the coupling bolt inserted through the coupling means has an integrated structure, and the nut portion is formed in a polygon whose outer periphery can be restrained by a pliers or the like, and the nut portion and the bolt portion are A ground terminal receiving jig, wherein a bolt portion inserted through the mounting hole of the ground terminal and a casting of the cast-in heater body are electrically connected in a screwed state.