JP2000192285A - Surface treatment apparatus for cylinder block and masking device for surface treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a masking device which can be adopted even to a cylinder block and V-engine block having journal parts and is used for the surface treatment of the cylinder block. SOLUTION: The masking device of the cylinder block 1 for sealing a treating liquid when subjecting a cylinder bore surface 2 formed in communication with the internal space of the crank case part 4 to a surface treatment has a crank case part rear surface masking jig 51 for masking the general surface of the crank case part 4 and a journal part masking jig 52 which is mounted at the crank case part rear surface masking jig 51 and masks the journal part 6. The entire part of the rear surface of the crank case part 4 is masked by both of these masking jigs 51 and 52.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment apparatus and a surface treatment method for applying a surface treatment such as plating or pretreatment to an inner wall of a cylinder bore in which a piston slides in a cylinder block constituting an automobile engine. The present invention relates to a masking method for processing.

[0002]

2. Description of the Related Art Conventionally, the material of a cylinder block has been changed from cast iron to aluminum alloy in order to reduce the weight of an engine. Since the cylinder bore formed in the cylinder block serves as a sliding surface of the piston, a cast iron liner is provided on the cylinder bore surface for the purpose of improving wear resistance, and nickel is used for further improving performance. Etc. are plated. As a method of performing the plating, an electroplating method in which a workpiece to be processed is immersed in a tank containing a processing liquid to perform plating is generally used. However, in these methods, a plating film is formed also on a portion other than the inner surface of the cylinder bore to be plated, so that the amount of processing chemicals is remarkably reduced. Since the number of brought into the process increases, the cost increases, and the liquid management becomes complicated.

Therefore, a method has been adopted in which a processing liquid is introduced only into the inner surface of the cylinder bore, which is the surface to be plated, of the work to increase the processing efficiency. In this case, it is necessary to seal both ends of the opening of the cylinder block, that is, two openings of the opening on the cylinder head side and the opening on the crankcase side so that the processing liquid does not leak. Since the opening on the cylinder head side is a smooth processed surface, it can be sealed by pressing a flexible rubber plate or the like such as a gasket.
As a method of sealing the crankcase side end of the cylinder bore surface, for example, as shown in FIG. 9 quoted from Japanese Patent Application Laid-Open No. Hei 7-118891, a force is applied to the elastic seal member 300 so as to expand outward. A method of sealing by pressing against the inner wall 301 or a method of pressing a pre-molded seal member or an expandable and deformable seal member against a cylinder end as described in JP-A-8-53798. There is.

[0004]

However, the above-mentioned conventional surface treatment method and masking method for a cylinder block and the apparatus used therefor have the following problems. 1) As shown in FIGS. 9 and 10, the cylinder bore inner wall 3
When plating is performed by sealing at the cylinder bore end portion 302 or the cylinder bore end 302, the plating layer 303 formed on the cylinder bore surface 301 is formed because the plating layer 303 is not formed at the sealed portion.
A step 304 is generated at 03. In recent years, in order to reduce the size of the engine and obtain a large displacement with this compact engine, when the piston reaches the sliding bottom dead center, the skirt located at the lower part of the side surface of the piston has a stepped portion of the plating layer 303. The engine is designed so that the cylinder block height is minimized by lowering below the section 304. However, in this case, there is a problem that the piston skirt portion is caught on the step 304 of the plating layer 303 to cause peeling of the plating. Further, the portion of the cylinder bore end 302 where the aluminum material is exposed has poor slidability, so that problems such as seizure and abrasion are likely to occur, and the cylinder is sometimes deformed by being hit by the piston.

2) Generally, when plating is performed using a nickel sulfate bath or a nickel sulfamate bath, gases such as hydrogen and oxygen are generated by electrolysis in parallel with the plating deposition reaction, and the pH of the plating solution is particularly low. In such a case, the generation of hydrogen gas increases. Also, in the pre-plating process, a large amount of gas is generated in the case of performing mixed acid etching, anodic oxidation treatment with a sulfuric acid bath, and electrolytic etching. However, FIG.
As shown in the figure, in the structure in which the cylinder bore inner wall 301 or the cylinder bore end 302 seals, the generated gas 305 stays in the vicinity of the seal portion in the cylinder bore 301. Problems such as a decrease in film thickness and burning of plating may occur.

3) In the flow plating and pre-plating in which the processing liquid flows through the cylinder bore inner wall 301, when the cylinder bore inner wall 301 or the cylinder bore end 302 is sealed, as shown in FIG. In some cases, the liquid flow 306 was disturbed, and the flow velocity was reduced, stagnated, an abnormal flow velocity, or the flow direction of the plating liquid was suddenly reversed at the sealing position. In dispersion plating in which fine particles such as silicon carbide are eutectoid, when the flow rate of the plating solution is not uniform, plating is scorched when the flow rate is low, and the plating solid is poor, which is an excessive fine particle eutectoid phenomenon. There was a possibility that problems such as a reduction in the amount of deposition and a luminosity of plating might occur. These inconveniences may also occur when fine particles are not eutectoid.

[0007] Further, in the cylinder block in which the crankcase is integrally formed, when viewed from the crankcase side, the journal portion supporting the crankshaft is provided so as to cross the cylinder bore, that is, to close the cylinder bore. . Therefore, when inserting the seal member from the crankcase side, in order to allow the seal member to pass through the journal portion, it is necessary to contract and deform the seal member once, pass through the journal portion, and then expand and restore the seal member. Therefore, the seal member is required to have durability and abrasion resistance to withstand deformation such as contraction and expansion which are considerably large in size, and also to have good chemical resistance to a plating solution, a pretreatment solution, and the like. It is difficult to select an appropriate material.

5) In the V-type engine, two cylinders are arranged in a fork at an upper portion of one crankcase, and are formed in a V-shape when viewed from the side. When the two cylinders are arranged so as not to be alternately overlapped in the longitudinal direction, a sealing device as disclosed in Japanese Patent Application Laid-Open No. 8-74095 can be used, but in general, in order to reduce the size of the engine, The two cylinders are arranged to overlap. When plating such a V-type engine, or when inserting a seal member from the crankcase side, two seal devices interfere with each other. Therefore, structural restrictions such as downsizing or offsetting the seal device are required. The masking device could not be inserted into the cylinder bore depending on the shape of the cylinder block. Therefore, as described in Japanese Patent Application Laid-Open No. H8-140882, plating must be performed twice for each V-shaped single bank, which requires twice the number of processing steps and is expensive.

6) In order to perform plating by an electroplating method, generally, plating is performed by applying a voltage while an anode is inserted into a cylinder bore. As shown in FIG. 10, when sealing is performed by the inner wall 301 of the cylinder bore and the end portion 302 of the cylinder bore, the length of the anode of the electrode 307 is shorter than the length of the cylinder bore. Was likely to be thin. Therefore, in order to apply a desired plating film thickness to the seal position 308, the plating time must be extended. In this case, the film thickness of the general surface of the cylinder bore 301 becomes too large, and the grinding amount in the honing process increases. This was disadvantageous in terms of cost. Also, in the pre-plating treatment such as electrolytic etching, the seal position 308 far from the electrode is hardly etched, which causes poor adhesion. If a desired etching is performed on the seal position 308, the amount of etching of the cylinder bore cylindrical portion becomes excessively large, and the dimensional accuracy is reduced such that the radius of the cylinder bore 301 is larger than a predetermined dimension. May deteriorate the adhesion due to the occurrence of smut.

[0010] The present invention solves the above-mentioned problems, and does not cause a defect such as a step of a plating film or scorching of plating on the inner surface of a cylinder bore, and can be applied to a cylinder block having a journal portion. ,
And a masking device for surface treatment.

[0011]

Means for Solving the Problems 1) In a masking device according to the present invention, a crankcase portion is formed integrally with a lower portion of a cylinder block main body portion, and a lower surface of the crankcase portion is formed as a substantially flat general surface. At the same time, when a part of this general surface is formed into a substantially semicircular journal portion, a body portion of the cylinder block is subjected to surface treatment on a cylinder bore surface formed in communication with the internal space of the crankcase portion. In a masking device for a cylinder block for sealing a liquid, a lower surface masking jig for a crankcase portion for masking a general surface of the crankcase portion, and a journal portion attached to the lower surface masking jig for the crankcase for masking the journal portion It has a masking jig. According to the above-mentioned masking device, the entire lower surface of the crankcase can be masked by the two masking jigs even when the cylinder block surface having the journal portion is subjected to the surface treatment on the cylinder bore surface of the cylinder block. Since the masking device does not seal at the cylinder bore surface or the cylinder bore end, it is possible to prevent the flow of the processing liquid from becoming uneven at the cylinder bore end. The surface treatment includes various treatments such as plating and pretreatment for plating.

2) In another aspect of the masking device according to the present invention, the journal masking jig includes a sealing device main body having a flow path therein, and a hollow portion fixed to the sealing device main body and having a hollow portion therein. And a journal portion sealing material communicating with the flow path of the sealing device main body. According to the masking device, the expansion medium is introduced into the hollow portion of the seal member for the journal through the flow path, and the seal member for the journal is expanded, whereby the mask is brought into contact with the journal and masked. be able to. A gas, a liquid, or the like is used as the expansion medium, and the sealant for the journal portion is preferably an elastic body, such as a flexible and deformable rubber, a resin, or an air tube. 3) In another aspect of the masking device according to the present invention, the seal member for the journal portion is formed in a plurality of annular shapes, and is spaced from the outer periphery of the seal device body so as to face the journal portions, respectively. Can be arranged. The sealing material is not limited to an annular shape, but may be any material as long as it can expand and contact the journal portion.

4) A surface treatment apparatus according to the present invention includes an electrode disposed inside a cylinder bore of a cylinder block having a crankcase portion and having a hollow cylindrical portion;
A processing liquid tank communicating with the cylinder portion, a recovery pipe communicating with the cylinder bore of the cylinder block and discharging the processing liquid to the processing liquid tank, and a power supply connected to the electrode and the cylinder block are provided. . In the surface treatment apparatus, with the end surface of the crankcase portion being masked, the treatment liquid is retained near the end of the crankcase portion from the treatment liquid tank via the cylindrical portion of the electrode, and then the cylinder bore is formed. The processing liquid may be introduced into the inside and returned from the collection pipe to the processing liquid tank.
Further, according to the surface treatment apparatus, a uniform surface treatment film can be formed on the entire inner surface of the cylinder bore. Since the seal is made at the end of the crankcase, the anode can be made longer than the length of the cylinder bore, and the end of the cylinder can be plated with a uniform film thickness and a uniform deposition amount.

5) A surface treatment apparatus according to the present invention includes a treatment liquid tank communicating with the inside of a cylinder bore of a cylinder block having a crankcase portion, an electrode disposed inside the cylinder bore, A masking device that is disposed at the top and has a hollow interior, and that has a seal material for the lower surface of the crankcase, a collection pipe that communicates with the inside of the masking device, and a power supply that is connected to the cylinder block and the electrode And According to the above surface treatment apparatus, after introducing the treatment liquid into the cylinder bore from the treatment liquid tank, the treatment liquid passes through the inside of the masking device from the circulation hole of the seal material for the lower surface of the crankcase, and is treated from the collection pipe. It can be configured to return to the liquid tank.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface treatment method and masking method for a cylinder block according to the present invention and the apparatus used for them will be described below in detail with reference to the drawings. [First Embodiment] First, a first embodiment will be described in the order of a surface treatment apparatus, a masking apparatus, and a surface treatment line.

The surface treatment apparatus 1 is a cross-sectional view of a surface treatment apparatus 21 and the masking device 22. The cylinder block 1 as an object to be processed is mounted on the work support 23 with the head surface 3 facing downward.
By disposing a head surface sealing material 24 such as a silicon rubber plate between the head surface 3 and the work support 23,
The head surface 3 is sealed. Positioning knock pins 25 are arranged on the work support 23. When the cylinder block 1 is mounted on the work support 23, processing holes 26 such as cylinder head fixing bolt holes provided on the head surface 3 are provided. By inserting the dowel pin 25 into the work piece, positioning during work chucking can be performed with high accuracy. The work support 23 and the head surface sealing member 24 are provided with openings 23a, 24a communicating with the cylinder bores 2. The cylinder bore 2 and the above openings are provided with the cylinder block 1 fixed on the work support 23. 23a and 24a communicate with each other. Further, the electrode 3 is provided below the work support 23 so that the processing liquid can flow into the cylinder bore 2.
1 and the processing liquid inlets 33, 34 formed in the fixed base 32.
Are arranged in a state of matching.

The electrode 31 has a hollow pipe-shaped cylindrical portion 35 vertically suspended upward, and the cylindrical portion 35 is fixed so as to be located at a fixed distance from the cylinder bore 2. The distal end 36 of the cylindrical portion 35 substantially coincides with the height of a cylinder bore end 37 (a boundary portion between the crankcase portion 4 and the cylinder bore 2) in a state where the cylinder block 1 is fixed to the work support 23. Although it is configured, it may be arranged so as to protrude from the cylinder bore end 37 toward the crankcase section 4. The electrode 31 is provided with a lead wire fixing portion 42 for fixing a lead wire 41 from a power supply 40 used for pretreatment and plating.
The work support 23, the electrode 31, and the fixed base 32 are bolts 4
3, the work support 23 and the electrode 3
1, insulating sealing members 44 and 45 such as silicon rubber are disposed between the electrode 31 and the fixed base 32 for preventing liquid leakage and electrical insulation. When metal bolts are used for fixing them, it is preferable to use an insulating collar or an insulating washer as necessary.

As for the material of the electrode 31, particularly when used for plating, a soluble electrode (in the case of nickel plating) in which metal nickel pellets or the like are filled in a mesh-shaped porous metal plate, or a titanium pipe is plated with platinum. Insoluble electrodes can be used. In addition, stainless steel or the like can be used for pretreatment such as electrolytic etching. In the plating step, the electrodes 31 are connected to the respective power sources 40 so as to serve as anodes, and in the electrolytic etching step so as to serve as cathodes.

Masking Apparatus Next, a description will be given of the masking apparatus 22 disposed above the cylinder block 1 shown in FIGS. The masking device 22 includes a crankcase portion lower surface masking jig 51 and a journal portion masking jig 52. The crankcase part lower surface masking jig 51 includes an attachment plate 54 attached to a vertically movable rod 53, a support member 56 fastened to the attachment plate 54 via a bolt 55, and an integral part of the support member 56. And a sealing material 57 for the lower surface of the crankcase, which is formed in a typical manner. The support member 56 includes the journal portion sealing material 6.
A notch 58 conforming to the outer peripheral shape is formed in the outer periphery shape of the crankcase 4. Are formed.

The journal masking jig 5
As shown in FIGS. 1 and 2, a substantially cylindrical sealing device main body 63 provided on a support member 56 via a bracket 62 and a plurality of And a journal portion sealing material 64 disposed therein. Inside the sealing device main body 63, the expansion medium 7 is provided.
5 is formed, through which the flow path 66 can flow.
Communicates with the hollow portion 77 of the journal sealing material 64. Further, the journal portion sealing material 64 has flanges 78 at both ends, and the flanges 7
By caulking the rings 79, 79 to 8, 78,
It is fixed to the outer peripheral surface of the sealing device main body 63. The sealing member 64 for the journal portion is attached so as to be expanded and contracted by the application of pressure to the gas or the liquid and to prevent the expansion medium 75 such as the gas or the liquid from leaking. The gas may be any of air, nitrogen and the like. The liquid may be water, oil, or the like.

Modified Example of Masking Apparatus The masking apparatus may be a single journal sealing material 84 formed along the length direction of the sealing device main body 63 as shown in FIG. At least one flow path 76 of the sealing device main body 63 may be formed. According to this masking device 85, the plurality of journal portions 6 can be masked at one time by flowing the expansion medium 75 into the seal material 84.

Outline of Surface Treatment Line FIGS. 4 and 5 are schematic diagrams of a treatment line for surface-treating the cylinder block 1 of in-line four cylinders. The transfer jig 15 is transferred to the cylinder block 1 by the transfer device 150.
After being placed on the wafer 1, the wafer is transported into the processing device 152 by the transport jig 151 (operation 1). Next, the transport jig 151 is lowered by the ejector 153, and the cylinder block 1 whose head surface is arranged on the lower side is set on the work support 23 and sent to the next step (operation 2).
The electrodes 31 are set in four cylinders. By lowering the masking device 22 from above the cylinder block 1 and operating the masking device 22,
The opening of the crankcase part 4 is sealed and the cylinder block 1 is supported (operation 3). In this state, the processing liquid 28 flows into the cylinder block 1 from the processing liquid tank 65, and the processing liquid outlet passage 67
And circulates to the processing liquid tank 65 through the Treatment liquid 28
, The masking device 22 is raised (operation 4). The cylinder block 1 is raised together with the transport jig 151 by the ejector 153 (operation 5). The cylinder block 1 is transported to the outside of the processing device 152 by the transport jig 151, and is transferred to the transfer device 15.
Return to 0. The transfer device 150 transports the cylinder block 1 processed in the process A to the process B, and transports the cylinder block 1 to be processed next onto the transport jig 151. In the case of a plating line,
A degreasing device, a pretreatment device, and a plating device are connected by a transfer device.

The operation of the surface treatment device 21 and the masking device 22 having the above configurations will be described below. First,
As shown in FIG. 1, the cylinder block 1 is set upside down with respect to the vehicle mounted state, and set in the surface treatment device. Then, as shown in FIG. 6, the lower surface masking jig 51 of the crankcase portion is lowered, and the sealing material 57 is brought into contact with the lower surface 4a of the crankcase portion 4 to seal. In this state,
A perfect circular notch 86 is formed by the journal portion 6 formed in the crankcase portion 4 of the cylinder block 1 and the semicircular notch portion 58 formed in the support member 56. Thereafter, as shown in FIG. 7, the journal masking jig 52 is operated to cause the expansion medium 75 to flow into the hollow portion 77 of the journal sealing material 64 to expand the journal sealing material 64. The seal is completed by making contact with the notch 86 having the perfect circular shape.

Next, as shown in FIG. 1, a processing solution 28 such as a pre-processing solution or a plating solution is pressure-fed from a processing solution tank 65 by a solution sending pump 66, and the processing solution inflow port 34 and the cylinder 35 of the electrode 31 And is introduced into the cylinder bore 2. The processing liquid outlet passage 67 provided in the work support 23 returns to the processing liquid storage tank 65 via the collection pipe 68. In the above embodiment, the processing liquid 28 between the inside of the cylinder bore 2 and the cylindrical portion 35 flows from the upper side to the lower side. However, the introduction and the introduction of the processing liquid 28 can be reversed. In this case, The processing liquid 28 on the surface of the cylinder bore 2 as the surface to be processed is caused to flow upward.

According to the first embodiment described above, the journal 6 of the cylinder block 1 and the semicircular notch 58 of the support member 56 are joined to form a perfect circular notch 76. Therefore, the journal portion 6 can be easily and reliably masked by expanding the annular seal member 64 having a hollow inside. Further, since the sealing position is on the lower surface 4a of the crankcase part 4, the flow of the processing liquid 28 at the cylinder bore end 37 becomes smooth, and no plating failure occurs, and the plating failure at the cylinder bore end 37 due to gas generation is reduced. it can. Further, the thickness of the cylinder bore end 37 can be easily controlled, and there is no need to provide a special buffer or a rectifying plate in the introduction path of the processing liquid 28. When the present invention is applied to a V-shaped cylinder block, all cylinders can be masked by masking from one direction. When a half-skirt type cylinder block is used, the lower surface 4a of the crankcase portion 4 is smooth. Since the masking device according to the present invention is used because of a complicated processing surface, reliable and easy masking can be performed. The machining of the cylinder block 1 is performed by installing the surface treatment step according to the present invention after machining the end face 4a of the crankcase portion 4 of the cylinder block 1 and before integrating the end face 4a with the ladder beam. The entire process flows smoothly, eliminating the need to remove the ladder beam.

[Second Embodiment] Next, a surface treatment 221 and a masking device 222 according to a second embodiment will be described. However, description of the same parts as those in the first embodiment will be omitted. FIG.
As shown in the figure, an internal space 257 is provided in the support member 256, a collection pipe 68 communicating with the internal space 257 is provided outward, and the lower end 68a is connected to the processing liquid tank 65.
It is arranged at the top of. Further, the supporting member 256 and the sealing material 2
An opening corresponding to the lower opening of the crankcase is provided in the cylinder block 58 so that they communicate with each other.
Is supported. Further, a shielding plate 261 is fixed on the upper portion of the cylindrical portion 35 so as to close the cylindrical portion 35 of the electrode 31.
According to the surface treatment device 221 and the masking device 222 having the above-described configuration, the treatment liquid 28 flows into the cylinder bore 2 from the treatment liquid tank 65 by the pump 66, and the inside 25 of the support member 256 flows from the lower opening of the crankcase portion.
7 through a collection pipe 68.
It is discharged to 8.

[0027]

According to the present invention, since the seal position is on the lower surface of the crankcase, the flow of the processing liquid at the end of the cylinder bore becomes smooth, plating failure does not occur, and the end of the cylinder bore due to the generation of gas is generated. Plating defects can be reduced. Further, the thickness of the end of the cylinder bore can be easily controlled, and there is no need to provide a special buffer or a rectifying plate in the introduction path of the processing liquid.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a surface treatment device and a masking device according to a first embodiment.

FIG. 2 is a side sectional view showing the masking device of FIG.

FIG. 3 is a side sectional view showing another embodiment of the masking device.

FIG. 4 is a plan view schematically showing a surface treatment line according to the present invention.

FIG. 5 is a schematic diagram showing a flow of operation in each step of FIG.

FIG. 6 is a cross-sectional view of the masking device according to the first embodiment, showing a state before a seal member for a journal is expanded.

FIG. 7 is a cross-sectional view of the masking device according to the first embodiment, showing a state after a journal-portion seal material is expanded.

FIG. 8 is a cross-sectional view illustrating a surface treatment device and a masking device according to a second embodiment.

FIG. 9 is a sectional view showing a conventional masking device.

FIG. 10 is a cross-sectional view showing a plating layer when a conventional masking and plating process is performed.

FIG. 11 is a cross-sectional view showing a gas retention and a flow of a processing liquid by conventional masking.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder bore 4 Crankcase part 6 Journal part 21,221 Surface treatment device 22,222 Masking device 28 Processing liquid 31 Electrode 35 Tube part 37 Cylinder bore end 51 Crankcase part lower surface masking jig 52 Journal part masking jig 53 Rod 54 Mounting plate 55 Bolt 56, 256 Supporting member 57, 258 Sealing material for lower surface of crankcase 58 Notch 59 Opening 62 Bracket 63 Sealing device main body 64 Sealing material for journal 75 Expansion medium 76 Flow path 77 Hollow part 78 Flange 79 ring 84 journal part seal material 85 masking device 86 perfect circular notch 260 communication hole

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tetsuya Kuroda 300-Takatsuka-cho, Hamamatsu-shi, Shizuoka Suzuki F-term (reference) 4K024 AA03 AB12 BB04 BC04 CB02 CB03 CB08 CB15 CB19 FA14 FA15 GA03 GA16

Claims (5)

[Claims] 1. A crankcase part is formed integrally with a lower part of a cylinder block main body part, a lower surface of the crankcase part is formed on a substantially planar general surface, and a part of the general surface is formed into a substantially semicircular shape. In a masking device for surface treatment of a cylinder block, which seals a treatment liquid when performing surface treatment on a cylinder bore surface formed in communication with an internal space of the crankcase portion, in a main body portion of a cylinder block formed in a journal portion, A crankcase part lower surface masking jig for masking the general surface of the crankcase part, and a journal part masking jig attached to the crankcase part lower surface masking jig and masking the journal part; The entire lower surface of the crankcase is masked with a jig Surface treating masking device Linda block. 2. A seal device body having a flow passage therein, wherein the journal masking jig is fixed to the seal device body, and a hollow portion formed therein communicates with a flow passage of the seal device body. A sealing material for the journal portion, an expansion medium is introduced into the hollow portion of the sealing material for the journal portion through the flow path, and the sealing material for the journal portion is expanded to abut on the journal portion to perform masking. The masking device for surface treatment of a cylinder block according to claim 1, wherein the masking device is configured as described above. 3. The seal member for a journal portion is formed in a plurality of annular shapes, and is arranged at intervals on an outer periphery of a seal device main body so as to face each of the journal portions. Item 3. A masking device for surface treatment of a cylinder block according to Item 2. 4. An electrode disposed inside a cylinder bore of a cylinder block having a crankcase portion and having a hollow cylindrical portion, a processing liquid tank communicating with the cylindrical portion, and communicating with a cylinder bore of the cylinder block. And a collecting pipe for discharging the processing liquid to the processing liquid tank, and a power supply connected to the electrode and the cylinder block. The end face of the crankcase portion is masked, and the electrode is removed from the processing liquid tank. After retaining the processing liquid in the vicinity of the end of the crankcase part through the cylindrical part, the processing liquid is introduced into the cylinder bore, and is returned from the recovery pipe to the processing liquid tank. Surface treatment equipment for cylinder blocks. 5. A processing liquid tank communicating with the inside of a cylinder bore of a cylinder block having a crankcase portion, an electrode disposed inside the cylinder bore, and disposed above the crankcase portion and hollow inside. Formed at the lower end thereof, a masking device having a sealing material for the lower surface of the crankcase having a through hole formed therein, a collecting pipe communicating with the inside of the masking device, and connected to the cylinder block and the electrode. After the processing liquid is introduced from the processing liquid tank into the cylinder bore, the processing liquid passes through the inside of the masking device through the flow hole of the seal material for the lower surface of the crankcase, and the processing liquid tank flows from the collection pipe. A surface treatment device for a cylinder block, characterized in that the surface treatment device is configured to return to the surface.