JP3915762B2 - Partial plating equipment - Google Patents

Description

In the present invention, a plating layer for imparting a predetermined function such as improvement of slidability and improvement of wear resistance is formed on a part of the surface of the piston so that plating does not adhere to the remaining portion. it relates portion plating key equipment.

As piston sliding shea the cylinder, from the viewpoint of such weight reduction, in order as the base material, formed of aluminum or an aluminum alloy or the like, to improve the slidability and abrasion resistance on the outer surface of the piston, A material that is electrolytically plated with Fe, Fe—Cr alloy, Cr, Ni, or the like is conventionally known from, for example, Patent Document 1 and the like.

Here, the piston has a portion that slides with respect to the inner surface of the cylinder and a portion to which the seal member is attached. In order to mount the seal member, an annular groove is formed at one or more locations on the outer peripheral surface of the piston so that the seal member is held by the annular groove. Do not make contact with the inner surface. Therefore, it is not always necessary to apply plating to the part where the seal member is mounted. Rather, since the groove is formed and has an uneven shape, when this part is plated, the current density partially changes, The surface condition changes, for example, the plating film thickness is not uniform. Therefore, it is necessary to perform precision processing on the mounting portion of the seal member and maintain the surface state. Based on the above, the plating for improving the wear resistance in the outer peripheral surface of the piston, limited to part of the sliding surface, the site or the like sealing member is mounted must be such not subjected to plating.

For this purpose, for example, a masking tape or the like is affixed to the surface of the workpiece, a portion not subjected to plating is masked, and immersed in a plating tank, thereby limiting to a part of the surface of the workpiece with a predetermined film thickness. It is common to form a plating layer. Then, after the plating process is performed, the masking tape is peeled off from the workpiece surface, whereby the workpiece is partially plated.
JP 2001-41008 A

  By the way, as pre-processing which performs plating, there exist a degreasing process, a pickling process, an alkali etching process, an acid activation process, a zinc substitution process, etc., and a water washing process is added between these processes. For this purpose, in addition to the plating tank, a processing liquid tank filled with the processing liquid for each step described above is arranged, and the workpiece is immersed in each tank in order. And, in order to perform partial plating on the workpiece, the masking tape is naturally affixed to the workpiece surface at a stage before entering the pretreatment step of plating. It is made to immerse in a pretreatment liquid tank one by one. Accordingly, the masking tape is also immersed in the processing liquid, and the processing liquid adheres to the masking tape. However, in the water washing step after each of the above pretreatment steps, the processing liquid attached to the masking tape is washed away. Will be.

  Since there is a step at the boundary between the part where the masking tape is affixed and the part where the surface of the workpiece is exposed, the processing liquid will stay at the corner of this step. The treatment liquid remaining in the corner portion may stay without being completely removed. When the workpiece is introduced into the plating tank in this state, when the plating process on the workpiece is finished and the workpiece is dried, the treatment liquid is applied to the boundary portion between the area where the plating layer is formed on the workpiece surface and the area where the plating is not performed. As a result, the dried material will stick and the streaks of impurities will remain at the boundary of the partially formed plating layer, not only the appearance will be damaged, but also corrosion will occur from that part. It becomes a problem.

  In addition, the work of attaching and peeling the masking tape is cumbersome, and it takes time and effort. Furthermore, depending on how the masking tape is applied, the boundary line of the plating layer may be disturbed. . Furthermore, there is a step between the plating layer forming part and the part where the masking tape is peeled off, and the plating layer is partially destroyed or peeled off when colliding with other objects. It cannot be said that there is no possibility of doing. In addition, if the shape is such that there are irregularities at the boundary of the partial plating, the masking tape may not be attached.

  The present invention has been made in view of the above points, and the purpose of the present invention is to place a portion where a plating layer of a workpiece is not formed in a non-contact state with respect to the workpiece when partially plating the workpiece. The object is to be able to mask and thus form a highly accurate plated product.

The present invention relates to a workpiece comprising a piston having a covered cylindrical piston crown portion having an annular groove formed on the outer peripheral surface and a skirt portion having a sliding surface formed on the outer peripheral surface. A partial plating apparatus for plating the sliding surface of the skirt portion without plating the annular groove forming portion, wherein the plating tank is filled with an electrolytic solution and provided with two anode plates A hanger that detachably supports the workpiece so that the piston crown portion is on the upper side and the skirt portion is on the lower side, and is immersed in the plating tank, and the hanger is provided on the hanger. A shield member made of an electrically insulating member facing the annular groove through a substantially constant minute gap and having an opening at a portion facing the sliding surface of the skirt portion; In the electrolyte solution of the plating tank, the anode plate is substantially parallel to the anode plates and faces the workpiece so as to be inclined together with the shield member. The present invention is characterized in that the sliding surface is plated by passing an electric current between them.

  Further, the partial plating apparatus in the present invention is in a non-contact state with respect to the workpiece between the cathode connected to the workpiece and the anode installed in the plating tank in a non-plating region of the workpiece surface. In addition, the shield member is arranged so as to form a substantially constant minute gap with respect to the workpiece.

  When an anode and a cathode are arranged in parallel in the electrolytic solution and a current is passed between the anode and the cathode, a plating layer is laminated on the cathode side. If the current density between the anode and the cathode is constant, a plating layer having a uniform thickness is formed. Further, when a shielding object is disposed between the anode and the cathode, current flows so as to bypass the shielding object. When the cathode is partially covered with the shielding object, the current density is different between the part facing the shielding object and the part directly facing the anode. When the shield is brought closer to the cathode side, a part where no current flows partially occurs on the cathode side. When the distance between the shield and the cathode is made to face each other through a minute space, for example, about several mm, the thickness of the plating layer is continuously increased from the outside to the inside at the end of the shielding area of the cathode. As a result, a region where no plating adheres is formed from a certain position inside the shield.

  In order to expose the portion of the workpiece where the plating layer is to be formed and to shield the portion where the plating layer is not formed, a shield member is disposed with respect to the workpiece via a minute gap. In addition, the shield member is held in a non-contact state with respect to the workpiece. Thus, in the pretreatment step, after the work is immersed in a predetermined treatment liquid tank, when the work is pulled up from the treatment liquid tank, the treatment liquid almost completely flows down into the treatment liquid tank. By immersing in the bath, the treatment liquid can be completely removed. Therefore, the surface of the workpiece can be introduced into the plating tank without any impurities such as a treatment liquid adhering thereto.

A plating layer is formed on the surface of the workpiece by setting the workpiece as a cathode in the plating tank, placing an anode facing the workpiece in a plating solution, and passing a current between the anode and the cathode. For this purpose, a pair of anode plates are disposed in the plating tank, and the work partially covered with the shield member is immersed in the plating tank at a position between the two anode plates. In addition, a uniform minute space is formed between the shield member and the workpiece. Therefore, on the surface of the workpiece, a transition area is formed in which the plating thickness continuously decreases to reach a predetermined width inside and outside the boundary between the part covered with the shield member and the part where the surface is exposed. In addition, the portion inside the transition region is not plated although it is immersed in the plating solution. As a result, partial plating can be performed only on a necessary portion of the workpiece. The shield member has an appropriate shape according to the relationship with the plating area of the workpiece. For example, when the plated area and the non-plated area are divided into upper and lower sides or left and right, the shield member is disposed opposite to the portion facing the non-plated area. When partial plating is performed only on a limited area of the entire surface of the workpiece, an opening corresponding to the part to be partially plated is formed in the shield member.

  When the interval between the shielding member for shielding and the workpiece is increased, the width of the plating transition area is widened, and there is a possibility of extending to a portion where plating should not be performed. On the other hand, if this interval is extremely fine, such as 1 mm or less, the transition region is substantially a line. However, the smaller the distance between the shield member and the workpiece, the more accurate alignment is required between the shield member and the workpiece, and the attachment / detachment of the workpiece becomes difficult. Of course, when it is necessary to perform partial plating with high accuracy, the distance between the workpiece and the shield member is made smaller. The shield member is held so as not to contact the workpiece. However, the shield member and the workpiece may be partially in contact with each other as long as the treatment liquid in the previous stage can be washed away so that it can be completely washed away.

  Specifically, if the distance between the shield member and the workpiece is larger than 5 mm, the transition area of partial plating becomes too wide. Therefore, the distance between the shield member and the workpiece is preferably 5 mm or less, more preferably 2 to 5 mm.

  Since the shield member is required only in the plating tank, the shield member is installed in the plating tank so that the surface of the work is covered with the shield member when the work is introduced into the plating tank. However, when performing plating, it is common to perform multi-stage pretreatment, and to immerse the workpiece in the plating tank immediately after the completion of the pretreatment. For this purpose, it is general that the work is supported by a hanger, and this hanger is immersed in the respective tanks in the respective pretreatment steps or the like by the conveying means in order. In this way, the work is supported on the hanger, introduced into the plating tank through the plurality of treatment liquid tanks in the previous process, and further sent to the subsequent process such as the washing tank from the plating tank, and the hanger is passed through the sequential process. When the hanger and the workpiece, and also the shield member, are not properly drained when they are pulled up, the liquid is brought into the subsequent tank, and the processing liquid and plating liquid in the tank are contaminated. Therefore, when the hanger is pulled up, the drainage from the hanger, workpiece and shield member must be good, and the liquid must be prevented from being brought into the next tank. For this purpose, the work and the shield member may be inclined and immersed in each tank. Then, when the hanger is pulled up, the processing solution, the plating solution and the like almost completely flow down into the tank and are not taken out to the next tank.

  The shield member may be fixedly provided on the hanger or may be configured to be detachable. In any case, the mask function by the shield member is sufficiently exhibited by mounting the work in a predetermined position with respect to the hanger. After plating is completed, the workpiece can be removed from the hanger and a new workpiece can be remounted.In other words, simply attaching and detaching the workpiece to the hanger requires work such as applying masking tape to the workpiece or peeling it off. do not do.

  It is desirable to transport the entire transport path from the start of the pretreatment process to the end of the final process by mounting the work on the hanger. For this purpose, the hanger is provided with a contact part to the workpiece, and when introduced into the plating tank, the contact part can be electrically connected to the cathode, and only when immersed in the plating tank. It can be energized. Therefore, the hanger is formed of a conductive member, and the rod-shaped member is formed of a conductive member and connected to a cathode provided outside the plating tank. The contact portion with the workpiece is also used as a member for holding the workpiece, such as a hook. Further, the shield member may be formed of a conductive member as long as the shield member is electrically insulated from the hanger to be energized, but it is desirable that the shield member has electrical insulation.

The workpiece to be partially plated is a piston. The piston has a covered cylindrical piston crown portion with an annular groove formed on the outer peripheral surface, and a skirt portion with an outer peripheral surface serving as a sliding surface. No plating is performed, and partial plating is performed so that the sliding surface of the skirt portion is plated. In the non-plating region, the gap between the workpiece and the shield member is very small, and the gap must be strictly managed. For this reason, it is required to ensure alignment between the workpiece and the shield member, and the workpiece and the shield member must be stably held so as not to be misaligned during conveyance. Furthermore, after plating is performed, it is necessary to take out the workpiece and mount a new workpiece.

  If importance is attached to the alignment between the workpiece and the shield member, it is desirable that the shield member is fixedly supported by the hanger and the position of the workpiece is adjusted with respect to the hanger. On the other hand, in order to easily attach / detach the workpiece to / from the hanger, both the workpiece and the shield member are supported so as to be attachable / detachable to / from the hanger. Then, after the plating process is completed, the shield member and the workpiece are taken out from the hanger, and the hanger supports a new workpiece, but further, the workpiece and the shield member are aligned. While the work and the shield member may be aligned, the work and the shield member may be aligned with respect to the hanger.

  In short, the shield member may simply cover the entire portion that is not plated. Therefore, the shield member does not necessarily need to be composed of a single member, and may be a divided type. For example, the shield member can be divided into left and right with respect to the hanger, and when the workpiece is mounted on the hanger, the shield member is opened, and the workpiece is closed by closing the shield member after mounting the workpiece. It is also possible to completely cover the portion that is not plated.

  According to the present invention, when partially plating a workpiece, a portion where the plating layer of the workpiece is not formed can be masked in a non-contact state with respect to the workpiece, and an excellent quality partial plating can be performed. It has the effect.

  First, as shown in FIG. 1, as a member to be plated, a shield member S is disposed opposite to a plate-shaped metal plate W (for example, an aluminum plate) W on the plating formation surface of the metal plate W. The shield member S has a predetermined width (30 mm or more) made of an electrically insulating member and a constant thickness. One end of the shield member S is fixed to the metal plate W, is raised vertically, and is separated from the metal plate W by a predetermined distance, for example, 20 mm. Then, using this as the maximum interval position, the sample P is tilted so that the gap continuously decreases to the position where it contacts the metal plate W, and is finally fixed to the metal plate W to form the sample P assembled. In FIG. 1, the numerical value shown in the rising direction of the shield member S means the distance between the metal plate W and the shield member S. Further, the scale in the direction orthogonal thereto is the distance from the end of the shield member S to the outside and the inside. The scale is in 5mm increments.

  The plating conditions including the type of the electrolytic solution, the distance from the anode plate, the current density, the temperature, the immersion time in the electrolytic solution, etc. are set, the cathode is connected to the metal plate W in this sample P, and the sample P is Plating was performed against the plate.

  The result is shown in FIG. As can be seen from the figure, the plating area changes according to the distance between the metal plate W to be plated and the shield member S. At the position where the distance is 20 mm, as shown by the line A in the figure, even if the position is 20 mm inside the portion covered with the shield member, the plating layer in the portion not covered with the shield member Plating having a thickness of about 20% is formed with respect to the thickness. The line B in the figure shows a position where the interval is 15 mm. At this position, only a few percent of the plating is formed at a position 20 mm inside the portion covered with the shield member S. Further, at the position where the distance is 10 mm, as shown by the line C in the drawing, the plating does not reach 20 mm inside the portion of the metal plate W covered with the shield member S. Furthermore, as shown by the line D in the figure, when the distance between the shield member S and the metal plate W is 5 mm, the thickness of the plating layer decreases from a position of about 5 mm outside the boundary of the shield member S, At 5 mm in the boundary portion of the shield member S, the plating hardly adheres. Further, as shown by the line E in the figure, at the position where the interval is narrowed to 2.5 mm, the thickness of the plating layer suddenly decreases from the outer 5 mm at the boundary portion of the shield member S, and the inside of the boundary portion is reduced. No plating layer is formed at 5 mm.

  From the above, if the distance between the shield member S and the metal plate W is 5 mm or less, partial plating is possible even if the gap is kept in a non-contact state. More preferably, when the interval between them is approximately 2.5 mm and the plating thickness on the metal plate W is about 15 μm, the transition from the portion to be plated to the portion to be unplated is about 10 mm. In addition, the thickness of the plating layer continuously decreases at this transition portion.

The first embodiment of the present invention will be described below with reference to FIGS. In the following description, in the reciprocating engine for a motor vehicle, a piston sliding in a cylinder as a work, it described as performing partial plating by limiting the sliding surface of the cylinder in the piston.

  The structure of the piston 1 is shown in FIGS. In the figure, the piston 1 has a piston crown 2 having a substantially covered cylindrical shape, a skirt portion 3, and a boss portion 4 to which a piston pin (not shown) is attached. A plurality of annular piston ring grooves 5 are provided on the outer peripheral surface of the piston crown 2 in the vertical direction, and piston rings are mounted in the piston ring grooves 5. The piston 1 reciprocates in the cylinder. As a result, the connecting rod connected to the piston pin attached to the boss portion 4 moves up and down.

  Of the piston 1 described above, the piston ring mounted in the piston ring groove 5 and the skirt portion 3 slide with the cylinder. That is, the sliding surface in the main body portion of the piston 1 is only the skirt portion 3. Moreover, in order to reduce the sliding resistance, as shown in FIG. 4, the sliding surface 3 a of the skirt portion 3 with the cylinder inner wall is a predetermined angle on both sides of the boss portion 4.

  In order to reduce the weight of the piston 1, the material itself is made of aluminum, an aluminum alloy, or the like, and the sliding surface 3 a portion of the skirt portion 3 is improved in slidability and wear resistance. Therefore, iron plating (or iron chrome alloy plating) is applied. However, the piston pin is inserted into the boss portion 4 and the piston ring groove 5 in the piston crown 2 is formed, both of which have complicated uneven shapes, so that the finish machining accuracy of these parts In order to maintain the resistance, avoid plating. That is, the piston 1 is subjected to partial plating limited to the sliding surface 3a. In order to perform partial plating on the piston 1, a portion not subjected to plating is masked. Thus, in order to partially plate the piston 1, for example, the hanger 10 shown in FIGS. 5 to 8 is used.

As shown in FIG. 7, the hanger 10 has a hanger body 11, and the tip of the hanger body 11 is a hook portion 12 that also serves as a contact for power feeding as will be described later. The hook 12 is provided in a conveying means, and is hooked on a rod 30 (see FIG. 9) that repeats pitch feeding and raising / lowering operations so that it is sequentially conveyed from each tank for pretreatment to a plating tank and a post-treatment tank. It has become. The hanger body 11 is composed of a support portion 11b formed by bending the lower end portion of the vertical flange portion 11a that extends substantially downward by approximately 90 °. However, since the piston crown 2 is provided with a groove or the like, there is a possibility that a processing solution, a plating solution, or the like is brought out in each tank. To prevent unauthorized removal of the liquid, that holds the state of tilting the piston 1 or less. For this purpose, when hooking the hook portion 12 on the rod 30, and the like give a slight angle between or the hanger body 11 to be tilted to some extent, or the vertical rod portions 11a and the supporting portion 11b . The hanger body 11 is made of a conductive metal, and its outer peripheral portion is covered with an insulating tube 13 made of synthetic resin or the like.

  A support rod 14 that is in contact with the lower surface of the piston crown 2 of the piston 1 is erected on the support portion 11 b of the hanger body 11. The support rod 14 is preferably formed of a rod-like member having electrical insulation and is for receiving the load of the piston 1. Further, at the front and rear positions of the portion where the support rod 14 is erected in the support portion 11b, there are four electrode rods 15 extending left and right by a predetermined length and bent upward by approximately 90 °. Is provided. The base end portion of the electrode rod 15 is connected to the hanger body 11 so that it can be electrically connected to the hanger body 11. The electrode rod 15 is covered with the insulating tube 13 except for its tip portion, the tip portion is exposed, and the exposed portion is an electrode portion 15a that is curved in an arc shape. 15a has a spring property.

  When the piston 1 is mounted on the hanger 10, the support rod 14 comes into contact with the lower surface of the piston crown 2 and the load of the piston 1 is received. The height of the electrode portion 15 a of the electrode rod 15 is lower than the tip of the support rod 13, and each electrode rod 15 comes into contact with the inner surface of the skirt portion 3 in the piston 1. In addition, as shown by the arrows in FIG. 4, the electrode portions 15 a provided at the four locations extend from the portion where the sliding surface 3 a in the skirt portion 3 is formed to have an arc shape to the portion where the boss portion 4 is provided. It is a shape change portion on the inner surface of the transition portion, and comes into contact with the inner surface so that a predetermined urging force acts. When the electrode portion 15a is brought into contact with the outer peripheral surface side of the piston 1, it is desirable that the electrode portion 15a is brought into contact with the position indicated by ▲ in FIG. As a result, the electrode portion 15a is brought into pressure contact with the inner surface of the piston 1, so that the piston 1 can be stably held and the piston 1 can be positioned.

  Further, as shown in FIG. 8, a shield member 20 is attached to the outer peripheral portion of the insulating tube 13 in the vertical flange portion 11 a in the hanger body 11. The shield member 20 is composed of two upper and lower cylindrical portions 21 and 22, and the upper cylindrical portion 21 is fitted to the lower cylindrical portion 22 by a predetermined length and fixed by means such as adhesion. . Here, the shield member 20 is divided into the upper and lower portions, and when the piston 1 is mounted therein, an opening 23 for exposing the sliding surface 3a in the skirt portion 3 provided on the left and right is formed. This is for masking so as to cover other than the moving surface 3a. Therefore, the shield member 20 does not necessarily need to be divided into upper and lower portions, and an opening may be formed in the peripheral body portion of a single cylindrical member. A connecting member 24 having a substantially T-shape extends on the outer surface of the shield member 20, and this connecting member 24 is joined to the clamp plate 25 with an insulating tube 13 provided so as to cover the hanger body 11. The plurality of screws 26 are fixed in a connected state. Here, since the shield member 20 is electrically insulated from the hanger body 11 by at least the insulating tube 13, the material is not limited, but it is desirable to use a molded product made of synthetic resin.

  By the way, although it is partial to the piston 1, since the surface is plated, at least the part where the plating layer is formed must be pretreated. As this pretreatment, for example, the steps of degreasing, water washing, pickling, water washing, alkaline etching, water washing, acid activation, water washing, zinc substitution, water washing, acid washing, water washing, zinc substitution, and water washing are generally sequentially performed. It is. Therefore, in order to perform each pretreatment process mentioned above, the tank filled with each processing liquid is arranged, and it is made to immerse in each of these tanks one by one. The means for conveying the piston 1 is provided in the upper part of each tank arranged in series. As shown in FIG. 9, the hanger 10 is hooked to the rod 30 that performs pitch feeding and raising / lowering operation in this conveying means. Is done. Here, in order to hold the hanger 10 stably, the rod 30 preferably has a square cross section.

  After performing the above-described pretreatment, iron sliding is applied to the sliding surface 3a of the piston 1 in the plating tank 31, as shown in FIG. The plating tank 31 is filled with an electrolytic solution, and anode plates 32 and 32 are provided so as to be immersed in the electrolytic solution. In addition, a rectangular rod-shaped rod 30 that constitutes the conveying means of the hanger 10 is arranged at a position between the anode plates 32, 32 in the upper position of the plating tank 31. The anode of the DC power supply 33 is connected to these anode plates 32, and the cathode is electrically connected to the hook 12 of the hanger 10 when the rod 30 is disposed in the plating tank 31. Then, by applying a direct current between the anode plate 32 and the rod 30, the piston 1 is subjected to iron plating only on the sliding surface 3 a in the skirt portion 3. As described above, when the plating is performed, the piston 1 may be kept stationary, but the plating can be performed while swinging up and down or left and right.

  Further, after the plating layer is formed on the piston 1, a post-treatment including water washing, tin plating, water washing, and drying steps is performed. Here, the tin plating after the iron plating is performed in order to improve the familiarity of the sliding surface 3a of the piston 1 with the cylinder, and it is not always necessary to perform the tin plating as a post-treatment.

  Thus, the piston 1 as a workpiece is attached to the hanger 10 from the start of the pretreatment to the end of the posttreatment. That is, the piston 1 is mounted on the hanger 10 before the start of the pretreatment, and the piston 1 is removed from the hanger 10 after the post-processing is completed. The hanger 10 is provided with a shield member 20 connected thereto, but the upper portion of the shield member 20 is open. Therefore, the piston 1 can be mounted so as to be inserted into the shield member 20 from the top of the hanger 10. Further, when the piston 1 is taken out from the hanger 10 after the plating process is finished, the piston 1 may be lifted upward. And in order to make attachment / detachment of this piston 1 easy, the upper part of the site | part which provided the shield member 20 in the hanger 10 is an open state. Therefore, the piston 1 can be easily attached to and detached from the hanger 10. In addition, as will be described later, since it is not necessary to apply a masking tape or the like to the portion of the piston 1 where plating is not performed, preparatory work for performing the plating process is not required. Can save.

  In a state where the piston 1 is mounted on the hanger 10, the piston 1 is in a non-contact state with respect to the inner surfaces of the cylindrical portions 21, 22 constituting the shield member 20 connected to the hanger 10, and is substantially uniform over the entire circumference. A gap is formed. Since the shield member 20 is fixedly provided on the hanger 10, it is necessary to arrange the piston 1 so as to always have a predetermined positional relationship with the hanger 10 when the piston 1 is attached to the hanger 10. The piston 1 abuts on the lower surface of the piston crown 2, but the electrode portion 15 a elastically abuts on the inner surface of the skirt portion 3 at four locations. In addition, since these electrode portions 15a are arranged on both sides of the boss portion 4 projecting inwardly, the shield member 20 is aligned only by mounting the piston 1 on the hanger 10, that is, the piston The distance between 1 and the shield member 20 is almost uniform over the entire circumference. In addition, the directionality of the piston 1 is also constant, and the sliding surface 3 a of the skirt portion 3 in the piston 1 is always disposed at a position facing the opening 23 of the shield member 20. Only the sliding surface 3 a is exposed to the outside, and the piston crown 2 and the boss portion 4 are covered with the shield member 20.

  When the hanger 10 equipped with the piston 1 is immersed in the plating tank 31 and a current is passed between the anode plate 32 and the rod 30, the contact between the hook 12 and the hanger body 11 in the hanger 10 becomes an energizing contact, and Since the contact between the electrode portion 15a of the electrode rod 15 and the piston 1 is also a contact for energization, the piston 1 is energized and a plating layer is formed on the outer surface of the piston 1. In the piston 1, a plating layer having a uniform thickness is formed only on the sliding surface 3a, and other portions are not plated. The entire piston 1 is immersed in the electrolytic solution in the plating tank 31. In addition, since there is a step at the transition portion from the sliding surface 3a to the boss portion 4, the current density at the step portion becomes high.

  Here, in the piston 1, only the portion of the sliding surface 3 a directly faces the anode plate 32, and the shield member 20 is interposed between the other portion and the anode plate 32. Therefore, as is apparent from FIG. 2, the distance between the inner surface of the upper cylindrical portion 21 and the portion of the piston 1 where the piston ring groove 5 is provided is, for example, approximately 2.5 mm, and the plating thickness on the sliding surface 3a is set. When the thickness is about 15 μm, the transition part from the part to be plated to the part not to be plated is about 10 mm, and the thickness of the plating layer continuously decreases at this transition part. become. Of course, if the distance is further reduced, the width of the transition portion can be narrowed. However, in the piston 1, even if such a transition portion exists, there is no particular problem. Moreover, if this space | interval is about 2.5 mm, the attachment or detachment of the piston 1 to the hanger 10 will become very easy. However, if it is necessary to make the width of the transition portion narrower, the distance between the shield member and the workpiece may be made narrower on condition that the shield member and the workpiece are not brought into close contact. Further, from the viewpoint of attaching and detaching the piston 1, it is desirable to set the interval to about 5 mm. However, if so, the width of the transition portion between the plated area and the non-plated area is somewhat increased. In short, when the distance between the inner surface of the shield member 20 and the outer surface of the piston 1 is about 2.5 mm to 5 mm, partial plating with extremely high accuracy is performed.

  In addition, the current density is prevented from increasing at the stepped portion from the sliding portion 3a to the boss portion 4 and the lower end portion of the sliding portion 3a, and a uniform current distribution is generated in the entire sliding portion 3a. The part and the lower part of the shield member 20 are partially overlapped on the sliding part 3a by about several mm. As a result, a substantially uniform current distribution is obtained over the entire sliding portion 3a. It should be noted that how much the shield member 20 is overlapped depends on the stepped portion from the sliding portion 3a to the boss portion 4 and the shape of the lower end portion of the sliding portion 3a, that is, whether the edge is present or rounded. What is necessary is just to set suitably from these.

  As described above, the outer surface of the piston 1 which is a workpiece is in a completely exposed state without contact with any member. Therefore, in the pretreatment stage, for example, treatment liquids for performing acid treatment, alkali treatment, etc. It can be completely removed in the water washing step performed after the above, and when introduced into the plating tank 31, the plating treatment can be performed in a state where the above-described treatment liquid is not attached at all. Therefore, the adhesion of impurities to the piston 1 after the plating treatment is eliminated, which is not only preferable in appearance but also can suppress the occurrence of corrosion and the like.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, members that are the same as or equivalent to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, the construction is such that the piston 1 and the shield member 60 as the workpiece are detachably attached to the hanger 40. Further, the piston 1 and the shield member 60 are held in an inclined state with respect to the hanger 40 by, for example, about 15 ° to 30 °.

  FIG. 11 shows a main configuration of the hanger 40. In the figure, the hanger 40 includes a vertical hook 42 and a support 43 connected to the lower end of the vertical hook 42. The support part 43 has support plates 43a and 43b made of a plate having a cross shape at the lower end of the vertical rod 42. Further, the tip end portion of the vertical hook portion 42 is a hook portion 42a as in the first embodiment described above, and this hook portion 42a is provided on the conveying means, and is hooked to a rod that repeatedly performs pitch feeding and raising / lowering operations. The illustration is omitted.

  As shown in FIGS. 12 and 13, a column 44 is erected at the intersection of the support plates 43 a and 43 b. A pair of piston holding plate springs 46 disposed so as to face the piston receiver 45 are connected to the tip of the support column 44. The piston receiver 45 is bent so that both ends of the connecting portion to the support column 44 are raised 90 degrees so as to contact the inner end surface of the piston crown 2 of the piston 1. Further, the piston holding leaf spring 46 is a leaf spring having a predetermined width, is bent obliquely downward from both ends of the connecting portion to the support column 44, and is bent downward inward from the most protruding portion 46a. Furthermore, the lower part is a folded portion 46b bent outward. Therefore, the most projecting portion 46 a is a spring force acting portion that is pressed against the inner surface of the skirt portion 3 of the piston 1, and the folded portion 46 b functions as a relief with respect to the lower end portion of the piston 1.

  Positioning / support pins 47 are erected on substantially both ends of the support plate 43a provided in the front-rear direction when viewed from the vertical flange 42, and on both ends of the support plate 43b provided in the left-right direction. The pedestal pin 48 is erected, and the shield member 60 is detachably supported by the support portion 43 of the hanger 40 by the support pin 47 and the pedestal pin 48. Further, clamp plate springs 49 for clamping and holding the outer peripheral surface of the shield member 60 are connected to the mounting positions of the base pins 48, respectively. The clamp plate spring 49 is bent inward in the middle so as to rise straight from the support plate 43b, and its innermost end 49a abuts against the outer peripheral surface of the shield member 60. This innermost end The upper part 49a is bent outward, and the innermost end 49a is provided to hold the outer surface of the shield member 60 so as to be clamped. Further, a portion above the innermost end 49a is a bent portion 49b bent outward, and the bent portion 49b functions as a calling portion of the shield member 60.

  Next, as shown in FIGS. 14 to 16, the shield member 60 has a shield body 63 with a step having an upper side serving as a small diameter cylindrical portion 61 and a lower side serving as a large diameter cylindrical portion 62. A pair of flange portions 64 and 64 are provided at the lower end portion of 63 so as to project outward in a 180 ° positional relationship. 14 and 15, positioning holes 65 are formed in these flange portions 64, and the tip portions of the support pins 47 provided on the hanger 40 are formed in these positioning holes 65. It is supposed to be inserted.

  The inner diameter of the small-diameter cylindrical portion 61 of the shield member 60 is slightly larger than the outer diameter of the piston crown portion 2 of the piston 1 as a workpiece, and specifically, a diameter difference of 2.5 mm or less is provided therebetween. . Further, the inner diameter of the large-diameter cylindrical portion 62 is sufficiently larger than the outer diameter portion of the skirt portion 3, and specifically there is a diameter difference of 20 mm or more therebetween. An opening 66 is formed over a predetermined angle including the transition from the small diameter cylindrical portion 61 to the large diameter cylindrical portion 62 and up to an intermediate position of the large diameter cylindrical portion 62. Two openings 66 are formed at an angular position of 90 ° with respect to the portion where the flange portion 64 is extended, and the outer peripheral portion of the large-diameter cylindrical portion 62 has an angle of preferably about 45 ° over a wide range. It has become a minute.

  Here, the support pin 47 is for positioning the shield member 60, and the shield member 60 is supported by the support pin 47 and the stepped pin 48. As is clear from FIG. 13, the support pin 47 has a pedestal portion 47b having a large diameter connected to the lower portion of the rod portion 47a having a spherical tip, and a portion below the pedestal portion 47b It is a threaded portion 47c. The screw portion 47c is screwed into a shaft portion 47d provided fixed to the support plate 43a, and a height adjustment ring 50 is interposed between the screw portion 47c and the shaft portion 47d. . Therefore, the height position of the base portion 47b is adjusted by adjusting the degree of tightening of the screw portion 47c to the shaft portion 47d. The pedestal pin 48 has a pedestal portion 48a having a planar shape at the tip. The pedestal portion 48a is screwed into the tip of the shaft portion 48b, and is interposed between the pedestal portion 48a and the shaft portion 48b. The height adjustment ring 51 is interposed, and the height position of the front end surface of the pedestal portion 48a can be adjusted by adjusting the degree of tightening of the pedestal portion 48a.

  Therefore, the shield member 20 comes into contact with the lower surface of the large-diameter cylindrical portion 62 by matching the height position of the tip surface of the pedestal portion 47 b of the support pin 47 and the pedestal portion 48 a of the pedestal pin 48. . In addition, since the support pins 47 provided in two places are inserted into the positioning holes 65 of the shield member 60, the shield member 60 is stably supported by the hanger 40 by minimizing the diameter difference therebetween. There is no risk of misalignment. Further, the hanger 40 is provided with a clamp leaf spring 49 so as to face each other, and since the innermost end 49a of the clamp leaf spring 49 protrudes inwardly, the shield member 60 is attached to the hanger 40. Sometimes, the shield member 60 causes the innermost ends 49a of the clamp plate springs 49 to be separated from each other, and the shield member 60 is fixed while being clamped between the clamp plate springs 49, 49.

  As shown in FIG. 13, the support portion 43 in the hanger 40 is inclined at a predetermined angle θ, preferably about 15 ° to 30 °, with respect to the vertical collar portion 42, and is therefore supported by the hanger 40. The piston 1 and the shield member 60 mounted so as to cover the piston 1 are inclined at the same angle. For this reason, as shown in FIG. 17, when the vertical collar 42 of the hanger 40 is suspended in the plating tank 31 in a vertical state, the plating tank 31 is inclined in a direction along the surface of the anode plate 32. At this time, the opening 66 of the shield member 60 faces the anode plate 32 located on both sides thereof. The entire hanger 40 is made of a metal that is a conductive member, and the outer surface portion is insulated. However, the hook 42a of the vertical hook 42 serving as a contact for supplying power to the piston 1 and the piston Insulating coatings are peeled off from the most protruding portion 46a of the holding plate spring 46, which is a contact portion with the piston 1, and the end surface 45a of the rising portion of the piston receiver 45, and functions as a contact for energization. Accordingly, the vertical holding part 42 engages with the rod connected to the DC power source in the first embodiment and is electrically connected to the hook 42 while being in contact with the energizing contact in the piston holding plate spring 46 and the piston receiver 45. It will be conducted.

  Also with the configuration described above, as in the first embodiment, the piston 1 can be partially plated on the portion other than the piston crown portion 2, and in particular, the skirt portion 3 can slide. Plating with a uniform film thickness can be performed on the surface 3a.

  The hanger 40 and the piston 1 attached to the hanger 40 and the shield member 60 are inclined so that there are almost no horizontal plane portions, so that the hanger 40 is placed in the plating tank 31 and other liquid treatment tanks. When the hanger 40 is pulled up after being immersed, the liquid flows smoothly along the slope and can be returned to the tank. Therefore, at the end of the lifting stroke, for example, the plating solution or other processing solution may substantially stay in the piston 1, the shield member 60, and the hanger 40, including the recessed portion on the upper surface of the piston 1. There is no loss of liquid. As a result, it is possible to reduce the consumption of the plating solution and the processing solution by taking out the solution, and to suppress the fouling of the next tank.

  Also, the hanger 40 can be individually attached to and detached from the hanger 40 with respect to the piston 1 and the shield member 60 that is mounted so as to be fitted to the piston 1 with a minute gap. ing. Accordingly, the hanger 40 is mounted so that the piston 1 is supported on the support 44 of the hanger 40. At this time, by fitting the piston 1 to the piston holding plate spring 46, the lowermost end portion of the skirt portion 3 of the piston 1 deforms the most projecting end 46a of the piston holding plate spring 46, that is, a position opposite to each other. The piston holding plate spring 46 provided on the piston 1 is inserted while being bent in a direction close to each other, and the piston crown portion 2 inner surface of the piston 1 is pushed to a position where it abuts on a piston receiver 45 provided at the tip of the support column 44, thereby 1 is held in a clamped state by the action of the piston holding plate spring 46.

  Next, the shield member 60 is mounted so as to be fitted to the piston 1 mounted on the hanger 40 as described above. When the piston 1 is almost covered with the shield member 60, the lower ends thereof are called by the bent portions 49b of the pair of clamp leaf springs 49, 49, and the bent portions 49b expand outward. As a result, the innermost ends 49a are separated from each other. Then, the support pin 47 is inserted into the positioning hole 55 of the flange portion 54 provided in the shield member 60. As a result, the shield member 60 is positioned, and when the shield member 60 is further pushed in, the lower end surface of the piston 1 comes into contact with the front end surfaces of the base portion 47b of the support pin 47 and the base portion 48a of the base pin 48. At the same time, the shield member 60 is clamped by the innermost ends 49 a of the clamp leaf springs 49, and the shield member 60 is fixedly held by the support portion 40 of the hanger 40.

  When the piston 1 and the shield member 60 are fixed to the hanger 40 as described above, the piston 1 and the shield member 60 are unnecessarily immersed in each tank for performing partial plating on the piston 1. There is no risk of displacement.

  When the plating process for the piston 1 is completed, the shield member 60 is first removed from the hanger 40, whereby the partially plated piston 1 can be easily detached from the hanger 40, and during this operation, There is no risk of other members colliding with the piston 1 for damage.

It is structure explanatory drawing of the jig | tool for evaluation used in order to perform the partial plating of this invention. It is a diagram which shows the change of the thickness of the plating layer formed in the edge part vicinity of a shield member according to the space | interval of a shield member and a workpiece | work. It is a front view of the workpiece | work in this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is an external view of the hanger for performing the plating process in Example 1 of this invention. It is an external view which shows the state which provided the shield member in the hanger of FIG. It is a fragmentary sectional front view which shows the state which provided the shield member in the hanger and mounted | wore with the piston as a workpiece | work. In Example 1, it is the structure explanatory drawing which shows the state which is performing partial plating to the piston. It is a general-view figure of the hanger for performing the plating process in Example 2 of this invention. It is sectional drawing which shows the state which mounted | wore the hanger of Example 2 with the workpiece | work and the shield member. It is DD sectional drawing of FIG. 6 is a plan view of a shield member in Example 2. FIG. It is EE sectional drawing of FIG. It is FF sectional drawing of FIG. In Example 2, it is the structure explanatory drawing which shows the state which is performing partial plating to the piston.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Piston crown 3 Skirt part 3a Sliding surface 4 Boss part 5 Piston ring groove | channel 10, 40 Hanger 11 Hanger main body 12 Hook 13 Insulation tube 14 Support rod 15 Electrode rod 15a Electrode part 20,60 Shield member 21,22 Cylindrical part 23, 66 Opening 30 Rod 31 Plating tank 32 Anode plate 33 DC power source 42 Vertical flange 43 Supporting part 45 Piston support 46 Piston holding plate spring 47 Supporting pin 48 Base pin 61 Small diameter cylindrical part 62 Large diameter cylindrical part 63 Shield body 64 Flange Part 65 Positioning hole

Claims (5)

With respect to a work comprising a piston having a covered cylindrical piston crown portion with an annular groove formed on the outer peripheral surface and a skirt portion with a sliding surface formed on the outer peripheral surface, the annular groove of the piston crown portion is It is a partial plating apparatus for plating the sliding surface of the skirt portion without plating the forming portion,
A plating tank filled with an electrolyte and provided with two anode plates;
A hanger that detachably supports the workpiece so that the piston crown portion is on the upper side and the skirt portion is downward, and is immersed in the plating tank,
A shield formed of an electrically insulating member provided on the hanger, facing the annular groove of the piston crown part through a substantially constant minute gap and having an opening at a part facing the sliding surface of the skirt part With members,
With the workpiece as a cathode, the anode and the anode plate in the electrolytic solution of the plating tank are faced so as to be substantially parallel to the anode plate between the anode plates and inclined with the shield member. Plating the sliding surface by passing current between
A partial plating apparatus characterized by having a configuration. The sliding surfaces provided at the skirt portion of the workpiece and exposed at the position of the opening of the shield member are located on both sides of the boss portion, and between these two anode plates in the plating tank 2. The partial plating apparatus according to claim 1, wherein the partial plating apparatus is arranged so as to face both sliding surfaces. 3. The partial plating apparatus according to claim 1, wherein the shield member is formed of a cylindrical member fixedly attached to the hanger, and the work is mounted on the inner side of the shield member. . The shield member is detachably attached to the hanger, and the hanger has a first support portion that supports the workpiece and a second support portion that supports the shield member. The partial plating apparatus according to claim 1, wherein the hanger body is provided with a hook that can be engaged with and disengaged from the cathode member. The partial plating apparatus according to claim 1 or 2, wherein an interval of a minute gap formed between the surface of the workpiece and the shield member is 5 mm or less.

Images