JP4677829B2 - Anodizing equipment for metal parts - Google Patents

Description

  The present invention relates to an anodizing apparatus for metal parts having a ring-shaped recess on the surface.

  In general, anodic oxidation is performed by using an acidic electrolytic solution containing sulfuric acid, chromic acid or the like to bring the object to be treated to the positive electrode side and energizing, for example, to oxidize the surface of the aluminum-based metal object to be treated. It is the processing method which forms thickness. However, when the alumite film thickness increases, electricity becomes difficult to flow due to its film characteristics (insulating properties), and the oxidation effect decreases. Therefore, it takes a long time to achieve the required film thickness, and the production efficiency is poor.

  In order to efficiently obtain an alumite film having a predetermined thickness, the current density can be improved and the time can be shortened by anodizing with a large current, but a large amount of Joule heat is generated. In recent years, aluminum alloys containing a large amount of silicon have been used to increase material strength. Such an aluminum alloy generates more heat. Therefore, if the generated heat is not removed efficiently, the hardness of the coating is lowered, and appears as a burning phenomenon. Accordingly, as the film thickness is increased, cooling to the alumite coating layer is required.

  As a method for preventing the burning phenomenon and cooling the coating layer, in Japanese Patent Application Laid-Open No. 11-236696, the electrolytic solution is treated at a flow rate of 30 cm / sec to 300 cm / sec in an electrolytic bath from a number of electrolytic solution injection ports. A method of forming an alumite coating on an object is disclosed. In this method, an alumite film formation rate of 4.8 μm / min can be obtained, but a high-power pump is required for spraying the electrolyte in the bath, which increases costs due to capital investment. Further, according to the method described in JP-A-4-198497, an alumite film formation rate of 12.9 μm / min is obtained. Furthermore, in this method, an alumite film can be formed on the surface of an aluminum alloy piston top or the like. However, it is not possible to form a coating on the groove portion such as the piston ring groove.

  Further, Japanese Patent Laid-Open No. 9-217200 provides a rotating spray disc at a position facing the top surface to improve cooling against heat generated when the alumite coating layer is formed on the surface to be processed. The alumite film formation rate is 15.0 μm / min.

In either case, a processing method and apparatus for the outside of the workpiece of an aluminum-based metal part, that is, a flat surface portion and a convex portion are disclosed, but high-speed processing to a concave portion (groove portion) cannot be realized.
JP-A-11-236696 JP 9-217200 A JP-A-4-198497

  An object of the present invention is to provide a surface anodizing apparatus for forming a metal oxide film in a concave portion of a metal part having a concave surface in view of the above points.

Means, actions, and effects to solve the problem

An apparatus for anodizing a metal part according to the present invention includes a first electrode portion for energizing a cylindrical object to be processed having a ring-shaped recess on a surface to be processed on the side peripheral surface, the first electrode portion, a second electrode portion having an electrode body when a voltage is applied between the, and the electrolytic solution supply means that teapot subjected electrolyte through the second electrode portion, and the first electrode portion and the second electrode portion energizing means for applying the voltage between, the anodic oxidation processing apparatus including the electrode body, the inner peripheral surface opposed to surround the treated surface, and the upper surface and the inner peripheral surface and the peripheral wall is opened the liquid A tank is provided, and the inner peripheral surface has a plurality of discharge holes that oppose the recess and inject an electrolyte toward the recess .

  The surface anodizing apparatus of the present invention has a second electrode portion having a discharge hole on the inside, and the discharge hole faces the concave portion of the object to be processed. Then, the electrolytic solution is ejected from the discharge hole of the second electrode portion by the electrolytic solution supply means, and at the same time, the object to be processed is made the first electrode (anode) through the holding means by the energizing means, and between the second electrode (cathode). Apply voltage. The electrolytic solution ejected from the discharge hole fills the concave portion of the workpiece, and the concave portion of the workpiece facing the second electrode portion is preferentially anodized by energization to form a metal oxide film. The electrolyte in the recess is heated by the heat generated by energization and the temperature rises, but the electrolyte that fills the recess is always supplied with a new, cold electrolyte from the discharge hole, and the rise in temperature of the recess is limited. Will be low. Accordingly, the concave portion of the object to be processed can be efficiently anodized without inconvenience such as a burning phenomenon, and a thick metal oxide film can be formed on the concave surface of the object to be processed in a short time.

  The anodizing apparatus for metal parts of the present invention includes a first electrode part, a second electrode part, an electrolyte supply means, and an energization means.

  A 1st electrode part is comprised with the conductor which contacts a to-be-processed object.

  Since the conductive material requires electrical conductivity, a metal material with good electrical conductivity is preferable.

  The object to be processed is made of metal and has a ring-shaped recess on the surface. Specifically, an aluminum alloy piston can be exemplified. It is preferable to use a cylindrical or rod-like ring groove having a ring groove that goes around the outer periphery on its outer surface. Here, the aluminum-based metal includes an aluminum metal and an alloy obtained by mixing other elements such as copper, zinc, and silicon with aluminum.

  Further, the first electrode part can be incorporated in a holding means for holding the object to be processed. Further, the holding means can have a rotation driving unit as a rotating means for rotating the workpiece to be held. The rotation driving unit may be configured such that the object to be processed rotates around the axis of the object to be processed. Further, the holding means may have a moving means for moving the object to be processed to, for example, an attachment / detachment position and an electrolytic treatment position.

  The second electrode portion includes an electrolyte passage, has an inner peripheral surface surrounding a side peripheral surface of the object to be processed, and communicates with the electrolyte passage on the inner peripheral surface and discharge holes facing the concave portion of the object to be processed. It is what has.

  The shape of the inner peripheral surface and the shape of the discharge hole can have different shapes according to the surface to be processed of the object to be processed. The shape of the discharge hole matched to the surface to be processed having a recess is generally circular, but in some cases, an elliptical shape or a rectangular shape is also preferable. Further, the discharge holes may be arranged inside the second electrode portion so as to be separated from each other in the extending direction of one or a plurality of rings. The number of discharge holes of the second electrode part, the size of the discharge holes, and the like can be freely set according to the object to be processed.

  When an aluminum alloy piston is used as the workpiece, the discharge hole diameter is preferably 0.5 to 2.0 mm and the number of discharge holes is preferably 4 to 32. In addition, since the second electrode portion requires electrical conductivity, a metal material with good electrical conductivity is preferable.

  The electrolytic solution supply means includes a storage tank that stores the electrolytic solution, an inflow path that connects the storage tank and the electrolytic solution passage, and a pump that is disposed in the inflow path and sends the electrolytic solution from the storage tank to the electrolytic solution passage. Can be configured.

  The electrolyte supply means may be provided with a cooling means for cooling the electrolyte, a temperature control means for controlling the temperature of the electrolyte, and a flow rate control means for controlling the flow rate of the electrolyte.

  Moreover, it is preferable that the 2nd electrode part is comprised combining the storage tank which collects electrolyte solution. The storage tank collects the electrolytic solution after being sprayed on the object to be processed and sends it out to the supply means. The storage tank main body may be a container with an open top or a sealed container depending on the object to be processed. One or a plurality of storage tanks can be installed in communication. Since the electrolytic solution often uses strong acid, the material of the storage tank body is preferably SUS316 or vinyl chloride. The storage tank may be formed integrally with the second electrode portion or may be detachable.

  The energization means is means for applying a voltage between the first electrode portion and the second cathode portion. This energization means preferably has current control means so that the current density can be adjusted. The current control means includes an ammeter, a voltmeter, a rectifier and the like, and a conventionally known one can be used.

  Hereinafter, based on an Example, the anodizing apparatus of this invention is demonstrated in detail. A functional explanatory diagram of the anodizing apparatus of this embodiment is shown in FIG. This anodizing apparatus is for anodizing a piston ring groove W1 of a piston W made of aluminum alloy. More precisely, of the three piston ring grooves W1, W2 and W3 formed from the top to the skirt on the outer peripheral surface of the top of the piston W, the top outer peripheral surface including the piston ring groove W1 on the top side is mainly used as the anode. It is an oxidation treatment.

  This anodizing apparatus has a holding means 1 for holding a piston W, an electrolytic cell 3 having an electrode portion 2 constituting a ring-shaped electrode, an electrolyte supply means 4, and an energizing means 5.

  The holding means 1 includes a reduction motor 11 fixed to an elevating part of an elevating device (not shown) fixed to an upper end of a frame (not shown), and a holding shaft 12 fixed to an output shaft of the reduction motor 11. Become. A detachable locking claw (not shown) is provided on the inner peripheral surface of the piston W at the lower end of the holding shaft 12. The locking claw is inserted in the axial direction so as to cover the inner cavity of the piston W from the lower end side, and the holding shaft 12 and the piston W are coaxial. In addition, a current collecting ring 51 constituting the energizing means 5 described later is fixed in the middle of the holding shaft 12 in the axial direction, and the current collecting ring 51 and an engaging claw (not shown) are electrically connected. And it is electrically connected to the piston W through the locking claw. The current collecting ring 51 and the holding shaft 12 constitute the first electrode portion of the present invention.

  A cylindrical rubber masking W5 is mounted and fixed on the outer peripheral surface of the ridge forming the boundary between the piston ring groove W2 and the piston ring groove W3 excluding the top of the piston W, and the lower part excluding the top of the piston W is Covered so that the electrolyte does not touch. The current collecting ring 51, the holding shaft 12, and the piston W constitute an anode.

  The electrode section 2 is composed of a rectangular substrate 21, a disk-shaped intermediate plate 22, a ring-shaped electrode body 23, and a conductor 24, as shown in FIGS. Has been. In addition, the electrode part 2 comprises the 2nd electrode part (cathode) of this invention.

  The substrate 21 is made of SUS316, and as shown in FIG. 4 and FIG. 5 in the longitudinal sectional view and the plan view, respectively, is a square plate shape with rounded four corners. A tunnel-like passage 212 having one end opened at the center and the other end opened on the side surface is provided.

  The middle plate 22 is made of vinyl chloride, and its longitudinal sectional view and plan view are shown in FIGS. 6 and 7, respectively. As shown in FIGS. And a stepped ridge 225 for forming a deep circular groove 223 and a shallow circular groove 224 coaxial with the deep circular groove 223 at the center on the upper surface side. Further, through holes 226 having both ends opened are formed in the circular recess 221 on the lower surface side and the shallow circular groove 224 on the upper surface side. Eight of the through holes 226 are provided in a ring shape with equal intervals. Further, the intermediate plate 22 incorporates a conductor 24 that is exposed from the outer peripheral surface thereof to the deep circular groove 223.

  The electrode body 23 is made of SUS316, and has a stepped cylindrical shape with two outer peripheral portions as shown in FIGS. Eight inflow holes 233 having a total of 16 discharge holes in two stages are formed on the inner peripheral surface 232 with eight inflow openings that open in the ring-shaped lower surface 231 and two stages in the axial direction. Has been. These through holes 233 are located at the same positions as the eight through holes 226 provided in the intermediate plate 22, and the through holes 226 of the intermediate plate 22 and the through holes 233 of the electrode body 23 communicate with each other, so that the electrolyte passage It becomes. Note that the opening on the inner peripheral surface 232 side of the through hole 233 serves as an electrolyte discharge hole, and both are open toward the axis of the electrode body 23. For this reason, electrolyte solution is discharged toward an axial center in a horizontal direction. In addition, since the conductor 24 is provided on the intermediate plate 22, the electrode body 23 is electrically connected via the conductor 24 when fitted to the intermediate plate 22.

  The electrolytic cell 3 having the electrode part 2 is made of vinyl chloride or SUS316, is a container having an opening at the upper end, and further has a collection port 31 for collecting the electrolytic solution collected at the bottom of the electrolytic cell 3 to the supply means 4. Is provided. In addition, the electrolytic cell 3 comprises a part of storage tank of this invention.

  The electrolyte supply means 4 is a cooling tank 41 that cools the electrolyte recovered from the electrolytic tank 3, a pump 43 that is a drive means that sends out the electrolyte, and a flow rate that is a flow rate control means that controls the flow rate of the electrolyte. It is composed of a total 44 and a pipe 45 for feeding an electrolyte solution pumped from the pump 43. Further, the cooling tank 41 is provided with a sub-tank 411 for storing the electrolyte, a refrigerator 412 that is a means for cooling the recovered electrolyte, and a temperature sensor 413 that constitutes a control means for controlling the temperature of the electrolyte. It has been. The pipe 45 constitutes the inflow path of the present invention. The cooling tank 41 constitutes a part of the storage tank of the present invention.

  The energizing means 5 is means for applying a voltage between the electrode body 23 and the piston W held by the holding means 1 and is composed of an ammeter, a voltmeter, a rectifier (not shown), and the like.

  Further, in this embodiment, when the electrolyte solution is ejected from the discharge hole 234 of the electrode body 23, the shape and size of the discharge hole 234 affects the effect of the anodizing treatment. When the anodizing process is performed, the discharge hole 234 may be elliptical or rectangular in some cases. Furthermore, as long as the uniformity of the discharge holes 234 of the electrode body 23 is ensured, the discharge holes 234 can be arranged in a plurality of sets on the inner peripheral surface of the electrode body 23.

  Further, in the embodiment, when the electrolytic solution is sprayed from the discharge hole 234 to the surface of the top outer peripheral surface including the piston ring groove W1 on the top side of the piston W that is the object to be processed, the inner peripheral surface 232 of the electrode body 23 The distance from the piston ring groove W1 constituting the surface to be processed affects the effect of the anodizing process. If the surface to be processed is too close to the inner peripheral surface 232 of the electrode main body 23 to be the cathode, there is a possibility that a short will occur. On the other hand, if the distance between the surface to be processed and the inner peripheral surface 232 of the electrode body 23 is too large, the electrolytic solution does not effectively reach the surface to be processed, and the anodizing treatment becomes insufficient. Therefore, the distance between the discharge hole 234 of the electrode main body 23 from the surface of the top outer peripheral surface including the two piston ring grooves W1 on the top side of the piston W connected to the anode is 2.0 to 15.0 mm. Is preferred.

  Further, when the electrolyte solution is injected, the portion facing the discharge hole 234 is strongly injected and jetted, and the rotation of the holding means 1 for holding the piston W is rotated for the problem that the formed alumite film is not uniform. Since the decelerating motor 11 is provided as a means, the alumite film can be uniformly formed by injecting the electrolyte while rotating the piston W.

  Next, the route of the electrolytic solution when anodizing the aluminum-based metal part will be described. The flow rate of the electrolytic solution cooled in the cooling tank 41 incorporated in the supply unit 4 is controlled by the flow rate control unit 44 and sent to the electrolytic cell 3 by the circulation pump 43. The electrolyte rises from the tunnel-shaped passage 212 of the substrate 21 in the electrolytic cell 3 to the chamber formed between the upper surface side recess 211 of the substrate 21 and the lower surface side recess 221 of the intermediate plate 22, and the through hole 226 of the intermediate plate 22 and the electrode body 23 passes through the electrolyte passage made up of 23 through-holes 233 and is sprayed from the discharge holes 234 to the top outer peripheral surface including the piston ring groove W1. Furthermore, after the electrolytic solution is sprayed from the discharge hole 234 and anodized, it accumulates in a liquid container of a small container composed of the electrode body 23 and the middle plate 22 and overblows upward. The overflowing electrolyte solution passes through the outside of the electrode unit 2 and is collected by the supply means 4 through the collection hole 31 at the bottom of the electrolytic cell 3. It is cooled by the cooling means 412 held by the supply means 4 and sent to the electrolytic cell 3 again.

  Hereinafter, the results of performing anodizing based on the examples of the present invention will be described. As shown in FIG. 1, in the electrolytic cell 3, an aluminum base metal piston W is fixed to the holding means 1 and connected to the anode via a current collecting ring 51. The electrode part 2 has a diameter of 1.5 mm, is provided with eight discharge holes 234 in one stage, is arranged in two stages, and constitutes an electric circuit together with the anode. The distance between the groove surface of the aluminum base metal piston W and the inner peripheral surface 232 of the electrode body 23 is 2.5 mm.

  Table 1 shows data on current density, processing voltage, rotation speed, electrolytic solution concentration, electrolytic solution temperature, alumite treatment speed, and alumite film thickness in each test.

  In the comparative example, the electrolytic treatment was performed by immersing only the tip portion of the piston as the object to be treated in the electrolytic solution by the conventional method.

  According to Table 1, as a result of anodizing the piston ring groove portion of the aluminum-based metal piston by the apparatus of the present invention, the anodizing apparatus of the embodiment of the present invention is healthy at a speed as fast as 25 μm / min. It became clear that an alumite film can be formed. The conventional apparatus has an alumite treatment speed of 1.3 μm / min, and the anodizing apparatus of the present invention has a film formation speed about 20 times that of the conventional apparatus. Even though the film formation speed is extremely high, the phenomenon of burning and the like does not occur. The electrolytic solution is ejected from the discharge hole, and the constantly cooled electrolytic solution is supplied to the surface to be processed, and the object to be processed is efficiently cooled. It is thought to be for this purpose.

  In the present embodiment, the discharge hole is circular, but it is of course possible to change it to a slit-like discharge hole that spreads in the direction in which the groove extends. In addition to the piston ring groove W1 of the piston W, an oxide film may be formed on the piston ring groove W2.

It is function explanatory drawing of the anodizing apparatus of this invention. It is an electrode part longitudinal cross-sectional view. It is an electrode part top view. It is a board | substrate longitudinal cross-sectional view. It is a board | substrate top view. It is a middle board longitudinal cross-sectional view. It is a middle board top view. It is an electrode main body longitudinal cross-sectional view. It is an electrode main body top view.

Explanation of symbols

1: Holding means 11: Deceleration motor 12: Holding shaft W: Object to be processed (piston) W1: First groove W2: Second groove W3: Third groove W5: Masking 2: Electrode 21: Substrate 22: Middle plate 23 : Electrode body 233: Through hole 234: Discharge hole 3. Electrolysis tank 4: Supply means 41: Cooling tank 412: Cooling means 413: Temperature control means 43: Pump 44: Flow rate control means 45. pipe

Claims (6)

A first electrode portion for supplying current to a cylindrical workpiece having a ring-shaped concave portion on a processing surface of a side peripheral surface;
A second electrode part having an electrode body to which a voltage is applied between the first electrode part ;
An electrolytic solution supply means that teapot subjected electrolyte through the second electrode portions,
Energizing means for applying said voltage between said first electrode portion and the second electrode portions,
In an anodizing apparatus comprising:
The electrode body has an inner peripheral surface facing so as to surround the surface to be processed, and a liquid tank whose upper surface is open with the inner peripheral surface as a peripheral wall,
An anodizing apparatus characterized in that the inner peripheral surface has a plurality of discharge holes that are opposed to the recess and inject an electrolyte toward the recess . Wherein the first electrode portion, anodization apparatus according the rotating means for rotating the object to be treated about the axis of the object to be processed is provided, in claim 1 you characterized. The second electrode part has a chamber in which an electrolytic solution is supplied below the liquid tank, and the electrolytic solution supplied to the second electrode part is an electrolytic solution provided in the chamber and the electrode body. The anodizing apparatus according to claim 1, wherein the anodizing apparatus is ejected from the discharge hole through a passage.   In the anodizing apparatus according to any one of claims 1 to 3,
  An electrolytic cell for collecting the electrolytic solution overflowed from above the liquid cell;
  A cooling tank for cooling the electrolytic solution supplied from the electrolytic tank,
  The electrolytic solution supply means supplies the electrolytic solution cooled in the cooling tank to the second electrode unit.
An anodizing apparatus characterized by that. The electrolyte supply means includes a storage tank that stores the electrolyte, an inflow path that connects the storage tank and the electrolyte passage, and an electrolyte that is disposed in the inflow path from the storage tank to the electrolyte path. The anodizing apparatus according to any one of claims 1 to 4 , further comprising: a pump for delivery. The anodizing apparatus according to claim 5 , wherein the storage tank has an opening for receiving the electrolytic solution after being sprayed on the object to be processed.

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