JP4747833B2 - Sheet metal member coupling structure and automatic transaction apparatus - Google Patents

Description

  The present invention relates to a coupling structure for coupling a sheet metal member coated with an insulating coating to another member, and an automatic transaction apparatus including the coupling structure.

  2. Description of the Related Art Conventionally, electronic equipment such as an information processing apparatus such as a personal computer and an automatic transaction apparatus has a structure in which various components and units are assembled to a metal structure. In order to incorporate components and units into a metal structure, metal sheets are overlapped and joined with screws or rivets, or joined by welding. In this case, as a means for grounding the metal structure for countermeasures against static electricity and EMI (electro magnetic interference), it is important to ensure electrical conduction between the stacked metal sheets.

  Conventional sheet metal parts use zinc-treated steel sheets with a hexavalent chromium film that has a rust-preventing effect. However, hexavalent chromium causes environmental degradation, so the review of its use on a global scale is ongoing. It has been. Therefore, at present, sheet metal parts (chromium-free steel sheets) provided with an organic coating for rust prevention that does not use hexavalent chromium have come to be used.

  Although this organic coating is a thin coating of about several μm, it has higher insulation than conventional anti-corrosion coatings, so when sheet metal parts are joined together, the organic coatings of both sheet metal parts are in contact with each other, Causes poor electrical continuity. Therefore, it has been a problem with EMI countermeasures and static electricity countermeasures.

Therefore, (1) a method of ensuring electrical continuity using a cut surface of a sheet metal part not coated with an organic coating, and (2) a pressure at the time of screwing with a joint part of the sheet metal part as a special knurled structure. There have been considered a method of obtaining conduction by digging into the organic coating, or (3) a method of removing the organic coating by rubbing the joint portion of the sheet metal parts. For example, Japanese Patent Application Laid-Open No. 2003-283154 discloses a method of obtaining conduction by causing the joint portion of the sheet metal parts to have a special knurled structure and bite into the organic film with a pressure applied at the time of screwing.
JP 2003-283154 A

  However, in the method of ensuring electrical continuity using the cut surface of the sheet metal part of (1) above and the method of biting into the organic film with the pressure at the time of screwing as a knurled structure of the coupling part of (2) above, The conduction state changes depending on how the cut surface is touched and how the knurled organic coating bites. Further, in the filed method (3), there is a problem that the rust preventive film is removed more than necessary and the metal surface is rusted.

  Then, an object of this invention is to provide the coupling | bonding structure of the sheet metal component which has a rust prevention effect and can ensure the favorable electrical continuity in a coupling | bond part.

In order to solve the above problems, the present invention provides a sheet metal member coupling structure in which a sheet metal member coated with an insulating coating is coupled to another sheet metal member, and a recess is formed by punching on the coupling surface of the sheet metal member, By forming the concave portion, the metal is pushed out to the periphery, and the insulating coating is peeled off from the top of the convex portion formed in a mountain shape around the periphery to expose the metal portion, and the other sheet metal member is insulated. The concave portion is formed by punching on the bonding surface with the sheet metal member, the metal is pushed out by forming the concave portion, and the top portion of the convex portion formed in a mountain shape around the peripheral portion is The insulating coating is peeled off to expose the metal portion, and the top of the convex portion is joined so as to contact the top of the convex portion of the sheet metal member .

According to the present invention, the insulating film is peeled off from the top of the convex portion formed in a mountain shape by extruding metal around the concave portion of the sheet metal member, and this top portion is exposed to the other metal plate member . Since the insulating coating is peeled off and the metal portion is coupled so as to come into contact with the top of the protruding portion, it is possible to easily ensure electrical continuity between the sheet metal member and the other sheet metal member. In addition, since the insulating coating is not peeled off at portions other than the top of the convex portion, it is possible to maintain a good antirust effect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. FIG. 1 is a cross-sectional view showing a joining structure of sheet metal members according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view showing a portion A of FIG.

  1 and 2, the sheet metal member 1 and the sheet metal member 2 are members that are coupled to each other. The surface of the sheet metal member 1 is coated with an organic coating 3, and the surface of the sheet metal member 2 is also coated with the organic coating 3. The sheet metal member 1 and the sheet metal member 2 are coupled by screws 6 with the coupling surface 4 and the coupling surface 5 facing each other. As shown in FIG. 2, a plurality of recesses 7 are formed on the coupling surface 4 of the sheet metal member 1, and a plurality of recesses 8 are also formed on the coupling surface 5 of the sheet metal member 2 on the opposite side.

  In FIG. 2, the recesses 7 and 8 are formed by punching by NCT (NC control turret punch press) processing, and the recess 7 and the recess 8 are provided at positions facing each other. When the recesses 7 and 8 are formed, the metal is pushed out to the periphery by punching out by pressing, and the mountain-shaped protrusions 9 and 10 are formed around the periphery. At the top portions 9a and 10a of the convex portions 9 and 10, the organic coating 3 is peeled off and the metal portions are exposed. This state is shown in FIG. FIG. 3 is a photograph showing the periphery of the recess.

  In FIG. 3, the black part on the right side indicates the inside of the concave parts 7 and 8, and the arcuate whitish part on the left side indicates the top parts 9 a and 10 a of the convex parts 9 and 10. A black part indicates that the organic coating 3 remains, and a whitish color indicates that the organic coating 3 is peeled off. The organic coating 3 is peeled off almost over the top portions 9a and 10a of the convex portions 9 and 10.

  When the sheet metal member 1 and the sheet metal member 2 are coupled, the top 9 a of the projection 9 of the sheet metal member 1 and the top 10 a of the projection 10 of the sheet metal member 2 are overlapped and coupled by the screw 6. In FIG. 2, the top portion 9a and the top portion 10a are not in contact with each other, but are separated for the sake of explanation, and in actuality, they are in contact with each other. The electrical connection between the sheet metal member 1 and the sheet metal member 2 is ensured by the contact between the top 9a and the top 10a. The organic coating 3 is not peeled off inside the concave portions 7 and 8 and around the convex portions 9 and 10, and therefore, the antirust effect can be maintained in these portions.

  By changing the diameter and depth of the recesses 7 and 8, the size of the protrusions 9 and 10 can be changed. By changing the size of the convex portions 9 and 10, the areas of the top portions 9a and 10a can be changed. By increasing the areas of the top portions 9a and 10a, the electrical continuity between the sheet metal member 1 and the sheet metal member 2 can be improved. According to the experiments by the present inventors, sufficient conductivity is ensured if the diameter of the recesses 7 and 8 is about 0.8 mm and the depth of the recesses 7 and 8 is about 0.2 mm. It was confirmed that

  When the surface of one sheet metal member (for example, the sheet metal member 2) to be joined is a member having good electrical conductivity, the concave portion 7 is formed only in the other sheet metal member 1 without forming the concave portion in the sheet metal member. The electrical connection between the two sheet metal members is formed by connecting the two sheet metal members by bringing the top portion 9a of the convex portion 9 around the concave portion 7 into contact with the surface of the sheet metal member having a good electrical conductivity. Can be secured.

  FIG. 1 shows a plurality of recesses 7 and 8 for both sheet metal members 1 and 2, but the electrical conductivity between the sheet metal members 1 and 2 increases as the distance between the recesses 7 and 8 increases. There is no doubt that will improve. However, punching out too many recesses 7 and 8 leads to an increase in processing time. On the other hand, if the number of recesses 7 and 8 is too small, sufficient electrical continuity cannot be ensured.

  Therefore, a jig (punch set) for forming a certain number of recesses was prepared and used to form recesses. FIG. 4 shows an example of a punch set. In FIG. 4, a punch set 11 in FIG. 4A has a screw hole 12 in the center and six punches 13 arranged around the screw hole 12, and is used for a sheet metal member to be coupled with screws. The intervals between adjacent punches 13 are equal.

  The punch set 14 of (b) is a structure in which six punches 13 are regularly arranged in two horizontal rows, and is used when the sheet metal members are overlapped at a portion having no member. The intervals between adjacent punches 13 in each row are equal. The punch set 15 of (c) is a structure in which six punches 13 are arranged in a horizontal row, and is used when the sheet metal members are overlapped with each other in the same manner as in (b) and is relatively elongated. Used for sheet metal parts. Also in this case, the intervals between adjacent punches 13 are equal.

  Regarding the relationship between the number of recesses formed by the punch 13 and the resistance value, the resistance value decreases as the number increases. The relationship between the number of recesses and the resistance value is shown in FIG. In FIG. 5, reference numeral 20 indicates a conduction resistance value when sheet metal members having good electrical conductivity are coupled to each other. Reference numeral 21 indicates that the resistance value when conducting through the recesses exponentially approaches the conduction resistance value 20 between the sheet metal members having good electrical conductivity as the number of recesses increases. ing.

  Here, when the number of the recesses is 6, the resistance value is substantially equal to the resistance value between the sheet metal members having good conductivity. Therefore, the number of punches 13 forming the recesses is required to be 6 or more. . Therefore, the punch sets 11, 14, and 15 shown in FIG. By disposing six or more punches 13 at regular intervals, the conductivity of the entire sheet metal member can be improved. The resistance values shown in FIG. 5 are values when the recess diameter is set to about 0.8 mm and the depth is set to about 0.2 mm.

  Next, the interval between the recesses 7 and 8 will be described. The interval between the recesses 7 and 8 varies depending on the frequency of noise whose resistance is to be improved. For example, when considering EMI suppression, in Japan, it is currently necessary to handle up to 1 GHz. This is because it is necessary not to cause resonance below the frequency that causes a problem on the sheet metal member. Therefore, the interval between the recesses needs to be 1/4 or less of the wavelength of the target frequency.

  Therefore, when the interval between the recesses is L, the interval L can be obtained by the following calculation formula. That is,

L = λ / 4 = c / (4 × f) (m)
Here, λ: wavelength (m), c: speed of light = 3 × 10 ⁸ (m / s), and f = frequency (Hz). As an example, when suppressing to 1 GHz, it is as follows. That is,
L = λ / 4 = c / (4 × f) = (3 × 10 ⁸ ) / (4 × 10 ⁹ ) = 0.075 (m) = 7.5 (cm)

  Therefore, providing recesses at intervals of 7.5 cm or less is effective in suppressing noise up to 1 GHz. In each punch set 11, 14, 15 shown in FIG. 4, the interval between adjacent punches 13 is 7.5 cm or less.

  Efficient recesses 7 or 8 can be formed by forming the recesses 7 or 8 in the sheet metal member 1 or 2 by the punch sets 11, 14, and 15 thus manufactured, and connecting them with screws 6 or the like. In addition, it is possible to improve the grounding property of the apparatus in which the sheet metal members 1 and 2 are incorporated, and to improve the EMI resistance and the electrostatic noise resistance. In addition, by preparing a plurality of punch sets of different types, it is possible to easily form the concave portion according to the difference in the coupling form of the sheet metal members.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the concave portion in the connection between the sheet metal members has been described, but the conductive effect by the convex portion around the concave portion in the present invention does not particularly require strong stress due to screwing or the like. That is, since the conductive effect can be secured if the convex portions come into contact with each other with a certain amount of force, the present invention can be applied to, for example, the coupling between the plate spring and the sheet metal member, or the coupling between the EMI gasket and the sheet metal member. Of course, the present invention can also be applied to connection between sheet metal members that do not require connection by screwing.

  FIG. 6 shows an automatic transaction apparatus as an apparatus to which the sheet metal member coupling structure of the present invention is applied. In FIG. 6, an automatic transaction apparatus 30 is an apparatus that is installed in a financial institution or the like and executes a transaction by a customer operation. In the cabinet 31 of the automatic transaction apparatus 30, units such as a card reader, a bill depositing / dispensing machine, a control unit, and a power supply unit (not shown) are mounted, and the outside front surface can be opened and closed for maintenance, inspection, etc. A front panel 32 and a front door 33 are provided. The front door 33 is a double door having a small door 34 on the surface.

  FIG. 7 is a perspective view showing the opening and closing structure of the front door. In FIG. 7, the front door 33 is rotatably attached to the cabinet 31 by a hinge 34. A rotation shaft 35 is provided inside the front door 33, and claws 36 and 37 are attached to the upper and lower sides of the rotation shaft 35. When the front door 33 is closed by operating a rotating means (not shown), the front door 33 is locked by hooking the claws 36 and 37 on the locking portions 38 and 39 provided inside the cabinet 31.

  The hinge 34 is fixed to the side wall 33 a of the front door 33. The hinge 34 and the side wall 33a are both coated with an insulating film for rust prevention, but it is necessary to establish electrical continuity between the hinge 34 and the side wall 33a. The coupling structure of the present invention is applied to the above. That is, the concave portion 7 or 8 shown in FIG. 2 is formed on the coupling surface of the hinge 34, and the concave portion 8 or 7 is similarly formed on the coupling surface of the side wall 33a so that they are overlapped and fixed with screws or the like. Needless to say, the coupling structure of the present invention can be applied to other portions of the automatic transaction apparatus 30.

It is sectional drawing which shows the joining structure of the sheet metal member of embodiment. It is an expanded sectional view which shows the A section of FIG. It is a photograph which shows the circumference | surroundings of a recessed part. It is a figure which shows the example of a punch set. It is a graph which shows the relationship between the number of recessed parts, and resistance value. It is a perspective view which shows the automatic transaction apparatus with which the joining structure of the sheet metal member of this invention is applied. It is a perspective view which shows the opening / closing structure of a front door.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Sheet metal part 3 Organic film 7, 8 Concave part 9, 10 Convex part 9a, 10a Top part 11, 14, 15 Punch set 13 Punch 30 Automatic transaction apparatus

Claims (3)

In a sheet metal member coupling structure for coupling a sheet metal member coated with an insulating coating to another sheet metal member,
Forming a recess by stamping on the coupling surface of the sheet metal member;
By forming the concave portion, the metal is pushed out to the periphery, and the top of the convex portion formed in a mountain shape around the periphery is peeled off the insulating film to expose the metal portion,
The other sheet metal member is covered with an insulating coating, and a concave portion is formed by punching out on the bonding surface with the sheet metal member. By forming the concave portion, the metal is extruded to the periphery, and is formed in a mountain shape around the periphery. The sheet metal member is characterized in that the insulating film is peeled off from the top of the projected portion so that the metal portion is exposed, and the top of the projected portion is connected to the top of the projected portion of the sheet metal member. Bonding structure. The sheet metal member coupling structure according to claim 1, wherein the inside of the concave portion of the sheet metal member is coated with an insulating film . The automatic transaction apparatus provided with the coupling | bonding structure of the sheet metal member of Claim 1 or 2.

Images