JP6510993B2 - Partial plating method, method of manufacturing metal shell for spark plug, method of manufacturing plated product, and method of manufacturing spark plug - Google Patents

Description

The present invention is a partial plating method in which a part, such as a part or a large part, of the surface (exposed surface) of a metal part or metal product (hereinafter, also referred to as a metal member or simply a member) is plated by electroplating. and, in the plating method of the metal shell of the manufacturing process of the metal shell for a spark plug, a method for manufacturing such a metallic shell for a spark plug using the partial plating method.

  Conventionally, as a partial plating method for electroplating (hereinafter, also simply referred to as plating) on, for example, the most part (plating target part) except for a part of the surface of a metal member, for example, a member that is a material to be plated Among them, there is a method of performing masking (insulation) by coating a resin or the like on a plating non-target portion (plating unnecessary portion) for plating. In this method, the masked object to be plated is put directly or in a rotating barrel and dipped in a plating solution to deposit plating, as in the case of general overall plating, and the masking material is removed after plating. . That is, this method requires not only the work for masking before plating, but also the troublesome work such as removal after plating. In addition, after plating the entire part instead of partial plating, the non-target plating part is immersed in a specific acid solution (acidic solution), and the plating film on the unnecessary part (hereinafter also referred to simply as plating) It is also practiced to obtain partial plating by peeling and removing.

  On the other hand, even in the partial plating, if the plating non-target part is a part or part of one end side of the plating object, the plating non-target part is above the liquid surface in the plating solution. It has also been proposed to form a plating film only on the surface of a plating target portion that is immersed and exposed so as to be exposed (projected) (Patent Document 1). However, in partial plating by such a method, there were the following problems to be solved.

Japanese Patent Application Laid-Open No. 05-98490

  During electroplating (due to the deposition of metal ions in the solution on the surface of the object to be plated (cathode)) by the reaction of chemicals in the plating solution accompanying the start of feeding (the start of energization between the electrodes) in electroplating. In the liquid, a large amount of gas (for example, hydrogen gas) is innumerably generated as minute bubbles. Such bubbles rise in the liquid, float on the liquid surface, and stay there. Therefore, among the parts where the object to be plated is submerged (plating target parts), in the vicinity of the liquid surface (part near the liquid surface) Easy to adhere to the surface. For example, like the object to be plated 10 (shown in the plating tank 101) shown in FIG. On the other hand, in the structure having a relatively small cross section and the bar 31 extending upward, the portion of the bar 31 is not plated, and the end face 11 is also the tip end face 13, There is a case where it is desired to surely plate with the same film thickness as the lower part (immersion part) in the drawing. In such a case, as shown in the same figure, substantially the entire rod 31 is projected above the liquid surface 200 m of the plating solution 200, and the liquid surface 200 m corresponds to the tip surface 13 of the main body portion 11. It is necessary to immerse in a small amount (for example, several mm). As a result, a substantial depth 200d of the liquid 200 (the distance between the liquid level 200m and the tip surface 13) becomes shallow on the tip surface 13. The shallow portion of the liquid is generated in the liquid and also becomes a shadow of a bubble group rising along the outer surface of the main body portion 11. Therefore, the portion tends to be a bubble reservoir in which air bubbles are accumulated. That is, in partial plating of such a member, a large number of air bubbles (air bubbles group) K stagnate and adhere, as shown in the enlarged view of FIG. It tends to be.

  In this manner, in the partial plating method (hereinafter, also referred to as partial plating method by exposure) in which the plating object is exposed by exposing a portion of the object to be plated, bubbles in the vicinity of the liquid surface (portion near the liquid surface) If stagnation or adhesion occurs, the current density to the object to be plated (cathode) at the portion near the liquid surface decreases due to the influence, and the progress of plating (deposition of plating (metal)) on the surface of the portion is hindered Be As a result, the thickness of the plating (coating) near the liquid surface becomes locally thinner than the others. Especially in the case of partial plating as in the case of the plated object 10 having the shape and structure as illustrated in FIG. That is, in such an object to be plated 10, the thickness accuracy of the plating (coating) on the front end surface 13 of the main body portion 11 locally becomes thinner than the others, and the film thickness accuracy of the plating decreases significantly. Incidentally, although the details of the object to be plated (member) 10 illustrated in FIG. 6 will be described later, it is a metal shell for a spark plug (in-process item).

  On the other hand, while the electroplating is in progress, replenishment for the plating solution, agitation for uniformly maintaining the concentration, and the like are performed. For this reason, it is also considered that the liquid flow by such stirring disperses and removes from the surface the air bubbles staying or adhering to the surface of the object to be plated. However, in the case of simply performing such stirring in the plating tank, the liquid level of the plating solution is wavy or the liquid level fluctuates up and down, so the liquid level should be maintained at a desired level of accuracy. I can not As a result, the deposition range of the plating at the portion near the liquid surface also changes up and down, which causes not only the local plating thickness accuracy drop but also the accuracy drop of the plating target portion (area) in the liquid level direction. . As described above, in the partial plating method by exposure, there is a problem that the plating accuracy is lowered, such as the accuracy decrease of the thickness of the plated film on the surface near the liquid surface.

  As understood from the above, in the partial plating method by exposure, application to a member requiring high accuracy for plating (hereinafter referred to as precision plated part (product)) is unsuitable. In the object to be plated (main metal shell) 10 as shown in FIG. 6, the portion of the bar 31 is bent into an L shape for the formation of a spark gap in a later step, and the bar accompanying the deformation thereof While the effect on the surface 31 is for the most part, the front end surface 13 of the main body portion 11 is required to be plated with a desired thickness with high accuracy. For this reason, as described above, in the metal shell that is such a precision plating part, after plating the whole as described above, the plating unnecessary parts are dipped in an acid solution (acidic solution) or the like and the unnecessary plating is subsequently performed. There is a problem that it is necessary to peel off, remove, or take a masking method, which lowers the production efficiency.

  The present invention has been made in view of the above problems, and among the surface of the object to be plated in the plating solution, removal of innumerable air bubbles staying or adhering to the surface of the portion near the liquid surface Partial plating method by exposure without causing deterioration of plating accuracy such as reduction in thickness of plating locally at the portion near the liquid surface, and so on. It is an object of the present invention to provide a method of manufacturing a metal shell for a spark plug using a partial plating method in a method of plating the metal shell in a manufacturing process of a metal shell for a plug.

In the invention according to claim 1, the object to be plated is immersed in the plating solution of the plating tank above the liquid surface with the non-target portion exposed and immersed, and is immersed only on the surface of the portion to be plated In the partial plating method for forming a plating film by electroplating,
While the plating is in progress, the liquid level is held at a predetermined level, and under the holding state,
In the plating solution which is at least near the liquid surface including the liquid surface of the plating solution, the liquid flow along the liquid surface toward the object to be plated is washed, and the liquid flow is used to wash the surface of the plating target portion near the liquid surface. The material is applied at a flow rate that allows removal of air bubbles staying or adhering to the surface, and the material to be plated is viewed continuously or intermittently when the material is planarly viewed under the applied liquid flow. And the upstream facing surface to the liquid flow on the surface is changed continuously or intermittently in the circumferential direction in the rotation.
The invention according to claim 2 is the partial plating method according to claim 1, characterized in that, when the liquid flow is viewed in a plan view, it is a liquid flow in a predetermined fixed direction in the plating tank.

The invention according to claim 3 immerses the object to be plated in the plating solution of the plating tank with the plating non-target portion exposed above the liquid surface, and is immersed only on the surface of the portion to be plated In the partial plating method for forming a plating film by electroplating,
While the plating is in progress, the liquid level is held at a predetermined level, and under the holding state,
In the plating solution which is at least near the liquid surface including the liquid surface of the plating solution, the liquid flow along the liquid surface toward the object to be plated is washed, and the liquid flow is used to wash the surface of the plating target portion near the liquid surface. So that the entire area of the surface in the circumferential direction of the object to be plated can be washed with this liquid flow, while applying a flow rate that allows removal of air bubbles that stay or adhere to the surface. It is characterized in that the flow direction of the flow is changed.
The invention according to claim 4 is set such that the liquid flow is given as a plurality of different flow directions in the plating tank when viewed in plan, and the flow direction is clockwise or counterclockwise. The partial plating method according to any one of claims 1 or 3, characterized in that the time interval is changed in order or in an appropriate order.
The invention according to claim 5 is the partial plating method according to any one of claims 1 to 4, wherein the flow rate is a constant flow rate within a predetermined allowable range.

The invention according to claim 6 is the main metal fitting for a spark plug, wherein the object to be plated is fixed in a butt-like manner to a rod for a ground side electrode for forming a spark gap on the tip end surface of a cylindrical member. The plating non-target portion is a major part including the tip end which is the free end of the rod, and the plating target portion is the entire cylindrical member and the portion other than the plating non-target portion in the rod The partial plating method according to any one of claims 1 to 5, wherein the partial plating is a metal shell for a spark plug, which is a portion.
The invention according to claim 7 is characterized in that the partial plating method according to claim 6 is used for the method of plating the metal shell in the manufacturing process of the metal shell for spark plug. Is a method of manufacturing a metal shell.

  In the present invention, as described above, since the liquid flow is applied to the plating solution at a flow rate enabling removal of air bubbles, it is generated in the plating solution and the surface of the plating target portion near the liquid surface Hereinafter, air bubbles (air bubbles) staying or adhering to the “surface” are removed in such a manner as to be washed by the liquid flow. Moreover, during the progress of plating, since the object to be plated is rotated as described above, the surface of the object to be plated that is directed upstream of the liquid flow changes in a circular manner with time. . As a result, the position of the back surface (shadow of the flow) located on the downstream side of the liquid flow in the surface changes, so that air bubbles may be concentrated on the specific back surface, or stagnation or adhesion (hereinafter simply referred to as "adhesion"). There is nothing to say. Thus, the entire circumference of the surface of the portion to be plated near the liquid surface in the portion to be plated is washed by the liquid flow of the plating solution. That is, when viewed from above (when viewed from the top) of the surface, the entire periphery is washed by the liquid flow, and the removal of the adhering air bubbles is obtained, so that the electricity resulting from the adhesion of air bubbles as in the prior art Since the reduction of the current density during the progress of plating is prevented, the deposition of plating can be stabilized on the surface near the liquid surface. And, in the present invention, the bubbles are not dispersed or removed by stirring the solution in the plating tank, but the bubbles are dispersed or removed by the solution flow, so there is a problem with the liquid level. It does not cause the occurrence of certain big waves and the like. As a result, the plating accuracy can be improved, including the plating thickness and the plating area in the level direction.

  In the present invention, application of a liquid flow along the surface of the plating solution to the plating solution at least near the liquid surface including the liquid surface is due to the fact that adhesion of air bubbles becomes a major problem. Among the objects, it is mainly the surface of the portion near the liquid surface in the portion to be plated which is immersed in the plating solution. Therefore, the flow may be applied deeper than this, for example, the entire depth of the plating solution, but this is not always necessary. Depending on the shape and structure of the object to be plated, the depth near the liquid surface where adhesion of air bubbles becomes a problem is different, so considering the depth of the plating liquid near the liquid surface to which the liquid should be applied It should be set.

  In the present invention, the “flow rate” may be set as appropriate within a range in which the surface can be washed to remove air bubbles attached to the surface and in a range that does not affect the plating deposition. In addition, the speed of the "rotation" of the object to be plated is as slow as possible so that the deposition of the plating is not disturbed (uniform plating can be obtained), and removal of the attached air bubbles is planar with the rotation. When viewed, it may be set in consideration of the (cross-sectional) shape and the like in plan view of the object to be plated, so as to be performed efficiently and uniformly all around in the circumferential direction. Then, this rotation may be continuous or, for example, may be rotated at an appropriate rotation angle and stopped for a predetermined time, and then may be intermittent rotation (discontinuous rotation) such as repeating this rotation and stop. When the surface near the liquid surface in the plating target portion is viewed in plan (cross section), if the shape is circular, it can be said that continuous rotation is preferable, but if this is, for example, a square, The liquid flow may be made to flow in the diagonal direction by rotating each 90 degrees. By doing this, smooth flow of liquid can be obtained, and more efficient bubble removal can be obtained. Such rotation may be repeated between normal rotation and reverse rotation at an appropriate number of rotations.

  In the present invention, “rotation” is preferably a rotation at the center or an arbitrary point in the object to be plated when the object to be plated is viewed in a plan view, but it is preferable to It may be made to revolve on a predetermined orbit (for example, a circle) while making it. That is, the rotation in the present invention may not be a simple rotation. The point is that the air bubbles generated during the progress of plating and attached to the surface may be rotated so as to be uniformly cleaned in the entire circumferential direction by the liquid flow of the plating liquid. In the partial plating method by exposure as in the present invention, the object to be plated is suspended, for example, by grasping the exposed portion on the liquid surface. Therefore, “rotation” in such a case is, for example, providing a chuck device capable of rotation control on the liquid surface, chucking the exposed plating non-target portion with its claw (gripping), and It suffices to control the rotation. Further, in the present invention, the plated object itself may be provided with a movement in the flow direction of the liquid flow.

  And, such a liquid flow may be a liquid flow in a predetermined fixed direction in the plating tank when viewed in plan as in the invention according to claim 2. For example, when viewed in plan, it is a flow of liquid in a certain direction from one side (end) of the plating tank to the other side (end) opposite to it. For example, in the case where the plating layer is rectangular when viewed in plan, it is preferable that the liquid flow in a laminar flow state between facing sides when the plan of the tank is viewed. In this way, the flow of the plating solution is stabilized, so it is easy to maintain the surface of the plating solution at a predetermined constant level (a level within a predetermined range), and the plating apparatus becomes complicated. I will not invite you. However, the flow direction of such a liquid flow may be changed during the progress of plating. That is, when viewed from above, when the plating tank is fixed and viewed, the flow direction of the liquid flow toward the object to be plated may be changed during the progress of plating.

  In each of the above inventions, the object to be plated is rotated when viewed in plan, but in the present invention according to claim 3, the entire area of the surface in the circumferential direction when the object is plated can be cleaned In addition, it is intended to change the flow direction of the liquid flow. And, also in this case, in the present invention according to the fourth aspect of the present invention, the liquid flow toward the object to be plated is applied as a plurality of different flow directions in plan view in the plating tank. The flow directions may be changed at appropriate intervals in a time sequence. For example, in plan view, in a rectangular plating tank, it is possible to apply a flow to the plating solution as a liquid flow horizontal to the vertical direction from each of the four walls, and in four walls, time intervals are sequentially Change the application of the liquid flow.

  In the present invention, the "predetermined liquid level" is a position (height position of liquid level) that should be the upper end (the boundary between the plating target part and the non-plating target part) of the part to be plated in the object to be plated The predetermined liquid level, that is, the level position of the liquid level may be set within an allowable range provided based on the required plating accuracy. That is, when the liquid surface is held at a predetermined liquid level, the allowable range of the liquid level is within the allowable range given based on the dimensional accuracy of the plating area, that is, the dimensional accuracy of the upper end position of the plating area. Should be set. Further, in the present invention, the flow rate is within a range where washing of the “surface” as described above and removal of air bubbles adhering to the surface is possible, and within a range that does not affect the plating deposition. It may be set appropriately on the basis, but as in the present invention according to claim 5, it may be a constant flow rate within a predetermined allowable range.

  Then, as in the invention according to claim 6, a bar material for a ground side electrode for spark gap formation is fixed in a butt shape on the outside of the tip end surface of the cylindrical member in the object to be plated. A metal shell for a spark plug, wherein the plating non-target portion is a major part including the end which is the free end of the rod, and the portion to be plated is the entire cylindrical member and the rod. In the base end portion of the cylindrical member other than the plating non-target portion which is the proximal end portion near the front end surface of the cylindrical member, retention or adhesion of the air bubbles can be effectively prevented even on the front end surface of the cylindrical member. However, a metal shell with high plating accuracy can be efficiently obtained. For this reason, according to the method of manufacturing a metal shell for spark plugs using such a partial plating method in the method of plating the metal shell in the manufacturing process of metal shells for spark plugs, the cost of the spark plug itself It is also expected to reduce the

It is a schematic diagram explaining the embodiment example which actualized the partial plating method of this invention, Comprising: A is a top view (figure seen from the top) of a plating tank, B is the center horizontal longitudinal cross-sectional view. In FIG. 1, it is typical explanatory drawing of the state currently rotated, when planarly seeing a to-be-plated thing in the advancing process of plating. The half-longitudinal sectional view explaining the process of assembling a spark plug using the metallic shell which is the thing to be plated after the end of partial plating. The plating tank used for another embodiment which materialized the partial plating method of this invention, and the plane schematic diagram explaining the kind of direction change of liquid flow. FIG. 5 is a schematic plan view for explaining changes in the direction of liquid flow using the direction change means of liquid flow in FIG. The metal shell for spark plugs, and the schematic cross-sectional view for description at the time of carrying out partial plating by the partial plating method by the conventional exposure by making this into a to-be-plated thing.

  Embodiments of the partial plating method according to the present invention will be described in detail with reference to the drawings. However, in the present embodiment, the metal shell for the spark plug shown in FIG. This object to be plated (hereinafter, also referred to as a metal shell) is for forming a spark gap on one side of the tip surface (upper end surface in the figure) 13 of the tubular member (main body portion) 11 of different diameter as described above. The bar 31 for the ground side electrode is fixed by welding or the like in a butt state. Then, as shown in FIG. 6, most of the upper and lower areas including the tip 33 which is the free end of the bar 31 (the part exposed above the liquid level 200 m of the plating solution 200). The portion to be plated is the entire upper and lower portion of the cylindrical member 11 and a predetermined upper and lower area of several mm from the tip surface 13 of the cylindrical member 11 to the tip 33 of the bar 31 (see FIG. Depth region 200d). Therefore, in the following partial plating, while the plating is in progress, the axis G of the cylindrical member 11 is made vertical, the tip surface 13 thereof is up, and the portion to be plated is immersed in the liquid. A predetermined portion including the free end 33 is made to project above the liquid surface 200 m of the plating solution 200 and is electroplated (for example, Zn plating). Although it will be described later that the majority of the bar 31 is a plating non-target portion (non-plating unnecessary portion) as partial plating as described above, the portion of the bar 31 is a plated metal shell. In the process of assembly and manufacturing as a spark plug, as described above, since it is bent into an L shape for the formation of a spark gap, peeling of plating at that time, abnormal discharge due to them, etc. To prevent the occurrence of

  First, a plating apparatus used for electroplating in the method of the present example will be described with reference to FIG. The plating tank (hereinafter, also simply referred to as a tank) 101 forming this apparatus is, for example, large enough to arrange a large number of objects to be plated 10 at an appropriate interval from each other in plan view (see FIG. 1A). The plating solution (plating solution for zinc plating) 200 controlled to a predetermined concentration and temperature has a predetermined liquid level (liquid level height position). It is put in). Although not shown, necessary anodes (zinc, iron, carbon or titanium) are disposed at appropriate positions in the plating tank 101 according to the disposition of the object to be plated (cathode) 10.

  On the other hand, in the present embodiment, when the tank 101 is viewed in plan, for example, from one side facing each other, the liquid flow of the laminar flow (horizontal flow) is secured to the other opposite side. In the tank wall 103 on the side (left side in FIG. 1) of the side wall, the plating solution 200 fed through a filtering device (not shown) by circulating means (not shown) all over the width and depth of the wall. A large number of in-tank feed ports (liquid flow start ports for liquid flow in the tank) 103a which are fed horizontally into the plating tank 101 are provided (see FIG. 1-B). Then, the plating solution 200 which is fed into the plating tank 101 and flows in the whole area in the width direction and the depth direction of the tank wall 105 on the right side of FIG. There are provided a number of outlets (flow end ports in the tank) 105b for feeding into the tank. Thereby, the plating solution 200 is opposed to the other in the plating tank 101 with the in-tank feed port (liquid flow start port of the liquid flow in the tank) 103a of one of the tank walls 103 of that tank as the upstream end. With the outlet 105b of the tank wall 105 (liquid flow end port in the tank) 105b as the downstream end, as shown by the broken line arrow in FIG. It is set to flow by the flow of the flow velocity. This liquid flow is controlled and controlled by a circulation system so as to be a liquid flow of a predetermined flow rate by means of a plating liquid circulation means (piping, valve, circulation pump, etc.) provided outside, including a filtration device. As it is set. In FIG. 1 and the like, two plating objects 10 or one plating object 10 is simplified for the sake of explanation.

  In such a plating tank 101, when viewed in a plan view as described above, the object to be plated (main metal shell) 10 is in a vertical state in which the tip end surface 13 of the cylindrical member 11 faces up in an appropriate arrangement. Thus, most of the bar 31 is exposed (projected) by a predetermined amount above the liquid surface 200 m and set so as to be immersed in the plating solution 200. On the other hand, on the liquid surface 200 m, in plan view, a chuck device 201 arranged corresponding to the object to be plated 10 is provided. It is set as the setting performed by grasping the tip part (part near the upper end of the exposed part) in the rod 31 of the metal shell 10), suspending it, and lowering it. Further, in the present example, each chuck device 201 at its immersion position has an appropriate rotational speed with the center (axis) G of the cylindrical member (cylindrical portion) 11 as the center of rotation when viewed in plan in each metal shell. It is made to rotate at the same speed continuously, and to rotate each metal shell.

  In this example, each metal shell 10 subjected to the pre-plating treatment is held by the chuck device 201 as described above, and a predetermined amount of a plating non-target portion is exposed and immersed above the liquid surface 200 m. . However, an appropriate allowable range is set for the liquid level (the level position of the liquid level) of the liquid level 200 m at this time. The holding and management of the liquid level may be performed by control of the immersion depth of the metal shell 10 (control of the lowering position of the chuck device 201) or overflow means provided in the plating tank 101. Here, as the overflow means, for example, an overflow port is provided on the wall surface of the tank, or when viewed from above in the tank, a number of overflow pipes are raised in place, the lower edge of the overflow port, the upper end of the overflow pipe (opening ) Should be in the liquid level.

  Therefore, in the present example, each metal shell 10 is immersed in the liquid, the liquid level 200 m is maintained at a predetermined liquid level, and the plating liquid 200 is directed along the liquid level 200 m in a predetermined direction by the circulating means. The flow may be applied, and each chuck device 201 may be rotationally driven, and power feeding for electroplating may be started in that state to advance (deposition) plating. In addition, the flow velocity of the liquid flow is set based on the speed and force at which removal of air bubbles (see the enlarged view in FIG. 6) adhering to the tip surface 13 which is the surface of the portion near the liquid level 200 m in the plating target portion is possible. ing.

  In this example, the plating proceeds (plating time) until the desired thickness of the plated film is obtained. During this process, the liquid flow is performed on one side of the tank 101. From the tank wall (inner wall surface) 103a toward the other opposite tank wall (inner wall surface) 105b, as shown by the broken arrow in FIG. 1, it flows as a horizontal flow in a certain direction . On the other hand, the object to be plated 10 is continuously rotated as described above, and the upstream surface to the liquid flow is continuously changed in the circumferential direction (see FIGS. 2A, 2B, 2C, and 2D). . As a result, when viewed from above, the entire area of the surface in the circumferential direction of the portion to be plated is washed, so removal of air bubbles that tend to stay or adhere to the surface is performed. As a result, since it is possible to prevent a decrease in current density due to the deposition of air bubbles during the progress of plating, a good homogeneous plating film can be formed without locally thinning the plating.

  Moreover, as in the case of the object to be plated 10 of the present embodiment, the level of the plating solution on the end surface 13 (the depth in FIG. 6) as the end surface 13 of the cylindrical member (main portion of the metal shell 10) Even if the portion 200d) is shallow and there is a shadow of the flow of air bubbles rising along the outer peripheral surface of the cylindrical member 11, the liquid flow is given also at the liquid level 200m, Furthermore, since the cylindrical member 11 is also rotated, adhesion of the air bubbles can be effectively removed. As a result, it is also possible to effectively prevent the plated film on the tip end surface 13 of the main body portion 11 of the metal shell 10 and the base end portion of the rod 31 from becoming thinner locally than others. And since the liquid flow for the removal of such air bubbles is not by the liquid flow by stirring (mechanical stirring or air stirring), it is by the flow in the horizontal direction of the plating solution 200 along the liquid level 200 m. The liquid level can be easily maintained at a predetermined liquid level.

  In the present embodiment, the planar arrangement of the objects to be plated may be such that the objects to be plated can be efficiently cleaned by the flow of the plating solution 200. Specifically, is there a sufficient distance in the flow direction so that the material to be plated located upstream of the liquid flow is not arranged to block the flow of liquid to the material to be plated downstream? It is preferable that the objects to be plated are not aligned in the direction of the liquid flow. These may be set in consideration of the size of the apparatus including the plating tank, the type of plating (batch processing, continuous processing), and the like.

  Thus, according to the partial plating method of this example, the plating film (Zn plating layer) is plated on the entire cylindrical member 11 and the desired region (proximal portion of the bar 31) with high accuracy. As a result, a metal shell 10 for a spark plug is formed. Such a metal shell is then sent to the assembly process as a spark plug, where, as shown in FIGS. 3A and 3B, the metal shell 10 has a hollow shaft shape including a center electrode 41 etc. The forceps 51 are assembled and fixed by caulking the rear end 15 of the metal shell 10 (FIG. 3-C). Then, as shown in FIG. 3C, by bending the tip side of the rod 31 for the ground side electrode into an L shape, the tip 33 of the rod 31 after the bending and the tip of the forceps 51 protrude from the tip A spark gap is formed between the center electrode 41 and the tip of the center electrode 41 and assembled as a spark plug 90. The structure itself of the spark plug 90 assembled and manufactured in this manner is conventionally known. Incidentally, the cylindrical member 11 constituting the metal shell 10 is a screw 16 for screwing into the plug hole, a positioning flange 17 at screwing, a polygon 18 for screwing, and the like from the top of FIG. 3C. , And a rear end 15 for caulking.

  And, by using the above-mentioned plating method, such a metal shell 10 can be made a metal shell with high plating accuracy without causing a drop in corrosion resistance at the tip end surface 13 and the vicinity thereof. As described above, according to the method of manufacturing the metal shell 10 including the plating step, the plating accuracy of the front end surface 13 and the like can be enhanced in the plating step. There is no need to peel off and remove unnecessary plating after the entire plating, nor to use a masking method. Therefore, although the partial plating method is used, a metal shell with high plating accuracy can be efficiently obtained. And since not only the manufacturing efficiency as a component but also the manufacturing efficiency as a spark plug will be improved, the cost reduction of the spark plug itself is also expected.

  In this example, the case where the liquid flow start port 103a and the liquid flow end port 105b of the liquid flow in the tank 101 are provided in the whole of the width direction and the depth direction of the tank walls 103 and 105 is exemplified. The present invention is not limited to this. This is because it is sufficient to wash the portion to be plated in the object to be plated 10 by the liquid flow and to remove air bubbles that are retained or adhered to the surface. Therefore, for example, speaking of the range in the depth direction of the liquid flow, depending on the shape, structure, size, etc. of the object to be plated, the dimension of the plating solution going downward from the liquid surface of the plating where the retention or adhesion of air bubbles becomes a problem. Depending on the area, it may be set as a range in which the removal is possible. In the above example, the exposed part on the liquid surface of the object to be plated is held by the chuck and suspended, and the chuck device is rotated as it is rotated. It may be embodied as an appropriate means such as may be embodied by a rotating means provided in

  Next, an embodiment of the invention according to claim 3 of the present invention will be described with reference to FIG. 4 and FIG. However, while the method of the present example and the method in the above example maintain the flow direction of the liquid flow constant in the above example, while the object to be plated is viewed in plan, it is rotated as compared with the present example. In the example, when the object to be plated is viewed in plan, it is not rotated, and when viewed in plan of the surface of the object to be plated, the flow direction of the liquid is set to the circumferential direction so that the entire region in the circumferential direction is washed. The only difference is that they are made to change when viewed in plan in. Also, the object to be plated and the portion to be plated are the same as those in the above example. Therefore, the description of the same or common parts as the above example is appropriately omitted, and the following description will be made centering on this difference. In the present embodiment, the flow direction of the liquid flow can be changed in either direction, in the vertical direction and in the horizontal direction, as shown by the broken arrows in FIG. 4 when the plating tank is viewed in plan. If and when. First, how to change the flow direction of the liquid flow in the present embodiment will be described with reference to FIG.

  As shown in FIG. 4, the plating tank 101 has, for example, four tank walls 103, 104, 105, and 106 that are rectangular and face each other in vertical and horizontal directions in plan view. Then, although not shown, a large number of plating solution feed ports (not shown) are provided so that the plating solution 200 can be fed into the plating tank 101 on any of the four tank walls. A liquid flow start port) is provided. In addition, a large number of outlets for feeding the liquid fed from the in-tank inlet of the opposite tank wall to any of the four tank walls to the filter device outside the tank through the circulation means ( The end of the liquid flow in the tank (not shown) is provided. Thereby, one of four types of liquid flow, which is directed upward or downward in the vertical direction in FIG. 4 and rightward or leftward in the leftward or rightward direction in FIG. It is set so that change control can be performed by opening / closing control of the provided valve or the like. The flow direction of the liquid flow in this example is assumed to be sequentially changed in the order of rightward, downward, leftward, and upward in FIG. It is done. In addition, since the in-tank inlet and outlet provided in each tank wall mutually only change the circulation direction of the liquid flow, those in each tank wall can change the flow direction in the circulation means In addition, it is obvious that it can also be used by installing the piping, the on-off valve, etc.

  That is, in this example, as shown by the broken line arrow in FIG. 5-A (upper left) by driving the circulation pump and operating the valve while plating is in progress, the tank on the left in the figure of the tank wall 101 is shown. The plating solution 200 is flowed from the wall 103 toward the tank wall 105 on the right, the flow state is maintained for a predetermined time, and after stopping, a predetermined time interval (stop time) is provided, as shown in FIG. 5-B (upper right). As shown by the broken line arrows in the figure, the plating solution 200 is flowed from the tank wall 104 to the lower tank wall 106 as shown by the broken line, the liquid flow is maintained for a predetermined time, and after stopping, the predetermined time interval is As shown by the broken line arrow in FIG. 5-C (lower right), the plating solution 200 is flowed from the tank wall 105 on the right toward the tank wall 103 on the left, and the liquid flow is maintained for a predetermined time. After the stop, a predetermined time interval is provided, as indicated by the broken arrow in FIG. 5-D (lower left). As, flowing plating solution 200 toward the tank wall 104 of the upper from the tank wall 106 of the lower illustration, the liquid flow state is maintained for a predetermined time, it stops. Then, the flow of the liquid by one round of liquid flow may be repeated many times during the progress of plating.

  Thereby, according to the present embodiment, while the plating is in progress, the liquid flow is left and right when viewed from above with respect to the object to be plated 10 held in a stopped state in the plating solution. The liquid flow is sequentially changed in every 90 degrees clockwise from the upper and lower four directions, and is intermittently applied. By this application, the whole area of the surface in the circumferential direction is washed with the liquid flow in plan view of the object to be plated 10. As a result, in the present example as well, since the bubbles attached to or to be attached to the surface of the object to be plated 10 are removed, the same effects as in the above-described example of the method can be obtained. That is, in the method of this example, in the above example shown in FIG. 1 and FIG. 2 in which the liquid flow direction is not changed, the object to be plated is intermittently rotated at intervals of 90 degrees when viewed from above at time intervals. Is the same as

  In such an example, the change of the direction of the liquid flow may be appropriately reversely rotated without making only one rotation (clockwise) when viewed in plan as described above, up and down, As shown on the left and right, they may be changed alternately. In the present embodiment, when the direction of liquid flow is changed (switched), the stop state of the liquid flow is kept for a predetermined period of time in order to ensure the stability of the liquid level, but it is necessary depending on the flow velocity. If not, the time interval after stopping may not be. In the present embodiment, the flow velocity may be gradually increased from the start of switching of the liquid flow (flow start) to a constant flow velocity. Further, in the above example, the object to be plated 10 is a metal shell for a spark plug as shown in FIG. 6, and the tip surface (upper end surface in the figure) of the tubular member (main body portion) 11 of different diameter making it. A rod 31 for the ground side electrode for forming a spark gap is fixed to one side of 13 by welding or the like in a butt state, and most of the portion including the free end of the rod 31 has a liquid level of 200 m. Since a predetermined amount of exposure (protrusion) is to be made above (protruding), the chuck claw 203 holds the tip end portion (portion near the upper end of the exposed portion) in the bar 31 and the tubular member is viewed from above. Although the case where the center (axis line) G of (cylindrical portion) 11 is rotated is described as a rotation center, this rotation may be rotated about the bar 31 for the ground side electrode (rotation center), etc. The position of the rotation center is set appropriately It is sufficient.

  The present invention is not limited to the above-described examples, and can be appropriately modified and embodied without departing from the scope of the present invention. For example, in the previous example, the liquid flows in four directions along the left, right, upper and lower lines when viewed in a plan view may be changed to liquid flows in more radial directions. Further, depending on the shape of the object to be plated, it may be alternately changed only in the flow direction (opposing direction) of the right row and the left row between straight lines. This is because it is preferable that the removal of the attached air bubbles be performed in the entire area around the surface of the object to be plated in a liquid flow. That is, the number of changes in the flow direction of the liquid flow may be appropriately plural depending on the cross-sectional shape of the object to be plated, the shape of the plating tank, the structure, and the like. In the above example, although the metal plating for the spark plug is used as the object to be plated, the present invention is not limited to this, as long as it is a member to which the partial plating method by exposure can be applied, shapes, structures, and the like. Can be widely applied regardless of whether they are precision plated parts. In addition, it is apparent that the plating metal is not limited to Zn, but can be applied to various kinds of electroplating such as Ni.

10 Plated object 101 plating tank 200 plating solution 200 m liquid level K air bubble

Claims (9)

A portion where the object to be plated is immersed in the plating solution of the plating tank above the liquid surface to expose the plating non-target portion, and the plating film is formed by electroplating only on the surface of the portion to be plated In the plating method,
While the plating is in progress, the liquid level is held at a predetermined level, and under the holding state,
In the plating solution which is at least near the liquid surface including the liquid surface of the plating solution, the liquid flow along the liquid surface toward the object to be plated is washed, and the liquid flow is used to wash the surface of the plating target portion near the liquid surface. The material is applied at a flow rate that allows removal of air bubbles staying or adhering to the surface, and the material to be plated is viewed continuously or intermittently when the material is planarly viewed under the applied liquid flow. A partial plating method, wherein the upstream facing surface to the liquid flow on the surface is changed continuously or intermittently in the circumferential direction in the rotation.   The partial plating method according to claim 1, wherein the liquid flow is a liquid flow in a predetermined fixed direction in the plating tank when viewed in plan. A portion where the object to be plated is immersed in the plating solution of the plating tank above the liquid surface to expose the plating non-target portion, and the plating film is formed by electroplating only on the surface of the portion to be plated In the plating method,
While the plating is in progress, the liquid level is held at a predetermined level, and under the holding state,
In the plating solution which is at least near the liquid surface including the liquid surface of the plating solution, the liquid flow along the liquid surface toward the object to be plated is washed, and the liquid flow is used to wash the surface of the plating target portion near the liquid surface. So that the entire area of the surface in the circumferential direction of the object to be plated can be washed with this liquid flow, while applying a flow rate that allows removal of air bubbles that stay or adhere to the surface. A partial plating method characterized by changing the flow direction of the flow.   The liquid flow is set so as to be applied as a plurality of different flow directions in the plating tank when viewed in plan, and the flow direction is sequentially clockwise or counterclockwise or in an appropriate order. The partial plating method according to any one of claims 1 or 3, wherein the time interval is changed.   The partial plating method according to any one of claims 1 to 4, wherein the flow rate is a constant flow rate within a predetermined allowable range.   The subject to be plated is a metal shell for a spark plug, in which a rod for a ground side electrode for forming a spark gap is fixed in a butt-like manner to a tip end surface of a cylindrical member. A main body for a spark plug, which is a major part including a tip end which is a free end of the rod, and the plating target portion is the whole of the cylindrical member and a portion other than the plating nontarget portion in the rod. It is a metal fitting, The partial plating method of any one of the Claims 1-5 characterized by the above-mentioned.   A method of manufacturing a metal shell for a spark plug, wherein the partial plating method according to claim 6 is used for a method of plating the metal shell in the manufacturing process of a metal shell for a spark plug. The manufacturing method of a plated article characterized by using the partial plating method of any one of Claims 1-5. A method of manufacturing a spark plug, comprising using the metal shell manufactured by the method of manufacturing a metal shell for a spark plug according to claim 7.

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