JP5532960B2 - Thermal spray coating processing method - Google Patents

Description

  The present invention relates to a method for processing a thermal spray coating formed on a bore surface of a cylinder block, for example.

  On the bore surface of the cylinder block, a flame (flame) is generated by arc, plasma, gas, etc., various metals and mixed metals are instantaneously melted, and atomized (pulverized) atomized by high-speed gas flow A thermal spray coating for improving the corrosion resistance, wear resistance, etc. of the bore surface is formed by a thermal spraying technique that causes collision / solidification of the liquid.

  When the sprayed coating is formed on the bore surface, usually, in the subsequent process, the bore end region where the bore faces the deck surface of the cylinder block and the sprayed coating portion of the end region are chamfered, and then the deck is formed. Surface machining is performed using, for example, a milling machine, and finally, honing for surface finishing of the sprayed coating is performed to complete the formation of the sprayed coating. Here, the purpose of the chamfering process is to prevent the sprayed coating from being pressed and peeled off from the bore surface in the subsequent deck surface processing, as will be described later. On the other hand, the deck surface machining is a finishing process for preventing gas leakage from the bore of the cylinder block, and is one of the important machining processes in the cylinder block machining process.

  Here, FIG. 5a shows a longitudinal cross-sectional view in which a spray coating y having a predetermined thickness: t1 is formed on the bore surface B1 of the cylinder block C. FIGS. 5b and 5c show the chamfering process for the spray coating. 2 shows the state after the two processing when the process is performed. In these drawings, the end region of the bore B where the bore surface B1 faces the deck surface D of the cylinder block C is indicated by T.

  As shown in FIG. 5b, one form of the state after the chamfering is a state in which the processing width at the time of chamfering: t2 is processed to be larger than the thickness of the thermal spray coating y: t1 (the chamfered surface: M In the case where chamfering is performed in this way, the processing purpose has been sufficiently achieved.

  On the other hand, as another form of the state after the chamfering, as shown in FIG. 5c, when the processing width at the time of chamfering: t2 ′ is processed smaller than the thickness of the thermal spray coating y: t1 A part of the sprayed coating y remains on the deck surface D.

  As shown in FIG. 5c, when a part of the sprayed coating y remains on the deck surface D, when the deck surface is processed in the next process, from a milling machine or the like when finishing the deck surface on a part of the sprayed coating y. There is a risk that the thermal spray coating y is peeled off from the bore surface B1 by this pressing force.

  Generally, the initial sprayed coating formed on the bore surface has a thickness of about 300 to 400 μm, and is finished to a final thickness of about 200 μm to 300 μm by honing. On the other hand, in chamfering after thermal spray coating formation, chamfering is not performed by aligning the axial center of the bore on which the thermal spray coating is formed. At present, chamfering is being carried out.

  This means that when chamfering is performed by aligning the bore axis, a precise device is required for the alignment (the bore itself has a machining error, so the bore axis is precisely defined). This is because it is extremely difficult to specify) and it takes time for alignment.

  In the method of performing alignment at an arbitrary position of the cylinder block when chamfering the end region of the bore as in the present situation, the axis of the bore is shifted by about 0.1 to 0.2 mm during the chamfering. In consideration of this, the actual chamfering width is about 500 μm from the front surface (surface facing the center of the bore) of the thermal spray coating, considering that the film thickness immediately after the thermal spray coating is formed is about 300 to 400 μm. While aiming at the chamfering width, the chamfering is carried out while allowing an error of about ± 0.3 mm. That is, since an error of about ± 0.3 mm is allowed with respect to the target of the chamfering width of about 500 μm, the chamfering is actually performed in a chamfering range as large as 200 to 800 μm.

  Furthermore, the present situation is that management regarding the degree of finishing of the chamfered surface after chamfering and the processing accuracy of the processed portion is mainly performed visually.

  With regard to the positioning of the bore during chamfering and the finishing management of chamfering, the precision of chamfering can be improved by using a precise device and taking both time and effort, as shown in FIG. 5c. Of course, the occurrence of a situation can be avoided or the possibility thereof can be reduced. However, on the other hand, if such a precise device is used, chamfering is performed with time and effort, and the finishing control is executed, the cost for manufacturing the cylinder block increases. In addition, it is inevitable that the processing time of the cylinder block is prolonged.

  Here, turning to the prior art, during the honing process after the formation of the thermal spray coating, the bore that has increased its inner diameter due to the thermal spray coating formation and the tool are prevented from coming off and coming off. Therefore, Patent Document 1 discloses a processing method for forming a thermal spray coating on a bore formed in a cylinder block so that its inner diameter increases toward the deck surface and performing honing. Has been.

  However, this processing method still solves the problem that, as shown in FIG. 5c, a part of the remaining sprayed coating interferes with a processing tool such as a milling machine and the sprayed coating is peeled off during the deck surface processing. It does n’t work.

Japanese Patent Laid-Open No. 2007-2111307

  The present invention has been made in view of the above-described problems, and the thermal spray coating formed on the bore surface receives any external force from the tools, devices, and equipment used in the deck surface processing during the deck surface processing. Accordingly, an object of the present invention is to provide a method for processing a thermal spray coating that can effectively solve the problem that the thermal spray coating is peeled off when an external force is applied.

  In order to achieve the above object, a thermal spray coating processing method according to the present invention is a thermal spray coating processing method for processing a thermal spray coating on a bore surface of a bore provided in a cylinder block, wherein the bore is a deck surface of the cylinder block. A first step of preparing a cylinder block having an endless projecting ridge extending in the bore extending in the inner peripheral direction of the bore in the bore end region facing the thermal spray coating on the bore surface , A third step of chamfering so as to form a machining surface passing through at least a part of the ridge, and a fourth step of finishing the deck surface. .

  The thermal spray coating processing method according to the present invention includes a cylinder block provided with an endless protrusion projecting into a bore in a bore end region facing a deck surface of the cylinder block among bores provided in the cylinder block. A processing method in which a thermal spray coating is formed on the bore surface, and chamfering is performed on a flat surface, curved surface, or a composite surface thereof that passes through at least the protrusion when chamfering is performed before finishing the deck surface. By this processing method, it is possible to completely prevent a part of the sprayed coating from facing the deck surface, so that when processing the deck surface, the processing tool or processing device applies force to the sprayed coating from the bore surface. It completely eliminates peeling off.

  Here, the shape of the ridge (cross-sectional shape) is not particularly limited, but it is essential that at least the endless shape that is continuous with the inner peripheral surface of the bore and the inside of the bore protrude. The outline of the cross section is an arbitrary shape such as a linear taper shape, a curved shape, a combination of a straight line and a curved shape, a trapezoidal shape, etc. from the middle of the bore toward the bore end (end facing the deck surface). Contour can be applied. Also, the method of processing the ridge is such that when the bore is machined while rotating the cutting tool and moving in the axial direction of the bore, the projection length of the cutting tool is reduced at the ridge formation site or the length of the projection is reduced. By remounting a short cutting tool, rotating it and moving it to the deck surface, it is possible to easily establish a bore having a protrusion.

  Also, in chamfering, chamfering is performed so that at least a part of the ridge is passed through, thereby forming a chamfered surface where the sprayed coating does not completely face the deck surface after chamfering. can do.

  To explain in more detail, whatever the shape or contour of the chamfering processing surface or processing line, if a protrusion having a longer overhang length than the thickness of the sprayed coating to be formed is formed, this protrusion By carrying out chamfering so that it passes through any part of the contour of the interior or inside, part of the sprayed coating formed on the surface is also removed at the same time on the protrusions removed by chamfering Will be. Since a part of the sprayed coating thus removed is a coating portion facing the deck surface before being removed, the spray coating coating portion facing the deck surface is completely eliminated by chamfering.

  The chamfering line can be applied to any line shape such as a linear taper shape, a curved shape, or a combination of a straight line and a curved shape.

  A sprayed coating is formed on the bore surface, the chamfering is performed as described above, then the finishing of the deck surface is performed, and the honing process, which is the final processing of the sprayed coating, is performed to the bore surface. The spray coating process is completed. In addition, the finishing process and the honing process of the deck surface may be performed at the same time, even if the processes before and after are reversed.

  Here, the bore of the cylinder block to be processed improves the wear resistance of the cylinder block bore of the cylinder unit mechanism as an actuator in addition to the bore of the cylinder block of the engine of the vehicle or the like. It includes an appropriate inner surface of a cylindrical member that needs to be made.

  Further, the spraying method on the inner surface of the bore may be any spraying form such as gas spraying, flame spraying, arc spraying, plasma spraying, etc., as the spraying material, metal powder such as aluminum and molybdenum, stellite alloy Further, alloy powders such as chromium-iron alloy and nickel-chromium, ceramic powders such as alumina and zirconia, and the like can be used. For example, in arc spraying, atomized powder obtained by appropriately melting a material wire is discharged from a spray gun as spray particles.

  According to the thermal spray coating processing method of the present invention described above, in the bore end region where the bore faces the deck surface of the cylinder block, the endless ridge projecting into the bore extends in the inner circumferential direction of the bore. And a part of the thermal spray coating formed on the bore surface is completely prevented from facing the deck surface by a very simple process improvement that only involves chamfering by passing a part of the ridge. Is done. Therefore, when a part of the sprayed coating is desired on the deck surface after chamfering, a part of this sprayed coating receives an external force from the tool or equipment used in the deck surface processing, which is a subsequent process, and the sprayed coating is caused by this external force. The problem of peeling off is effectively eliminated.

  Further, in the chamfering process, in particular, the bore to be machined in the cylinder block may be positioned at an arbitrary position of the cylinder block as in the conventional method (therefore, an apparatus for precise positioning is not required). In this case as well, by performing the chamfering process so as to pass through a part of the protrusion, it is possible to easily ensure at least the chamfering process in which the sprayed coating does not face the deck surface. Furthermore, since the precise positioning of the bore and the management of the precise chamfered portion can be made unnecessary, it is possible to suppress an increase in the processing time of the cylinder block including the thermal spray coating.

  As can be understood from the above description, according to the thermal spray coating processing method of the present invention, when chamfering the end region where the bore faces the deck surface, without performing the positioning of the bore with high accuracy as usual, Chamfering can be performed so that the thermal spray coating does not face the deck surface reliably, so that the thermal spray coating is peeled off from the bore surface by a processing tool etc. when finishing the deck surface, which is a subsequent process. It can be effectively deterred.

(A) is the longitudinal cross-sectional view explaining the 1st process of the processing method of the sprayed coating of this invention, More specifically, it is the longitudinal cross-sectional view which showed only a part of prepared cylinder block, (B), (c) is the schematic diagram which showed other embodiment of the protrusion formed in the bore. It is the longitudinal cross-sectional view explaining the 2nd process of the processing method of this invention following FIG. 1a. FIG. 3 is a longitudinal sectional view illustrating a third step of the processing method according to the present invention, following FIG. 2. (A), (b) is the schematic diagram explaining other embodiment of the chamfering processed surface. (A) is a longitudinal cross-sectional view explaining the sprayed coating formed in the bore | bore surface of the cylinder block by the conventional processing method, (b), (c) both perform the chamfering process with respect to the sprayed coating. It is the schematic diagram explaining the state after two processes in the case of.

  Embodiments of the present invention will be described below with reference to the drawings. In the illustrated example, the object to be processed is a bore formed in a cylinder block of a vehicle engine. However, the sprayed film processed by the processing method of the present invention is an actuator. It may be a sliding surface of a cylinder (block) constituting the cylinder unit mechanism. In order to facilitate understanding, only the portion of the cylinder block where the bore is opened is taken out and illustrated. Further, it goes without saying that the protrusion formed in the end region facing the deck surface of the bore may have a cross-sectional shape and contour other than the illustrated embodiment.

  FIG. 1a is a longitudinal sectional view for explaining the first step of the thermal spray coating processing method of the present invention. FIGS. 2 and 3 show the second step and the third step of the processing method of the present invention, respectively. It is the longitudinal cross-sectional view demonstrated.

  In the first method shown in FIG. 1A, the thermal spray coating processing method according to the present invention extends in the inner peripheral direction of the bore surface 1a in the bore end region 1c where the bore B faces the deck surface 1b of the cylinder block 1. A cylinder block 1 is prepared which is provided with an endless ridge 1d protruding into the bore B.

  Here, it is as follows when the opening method of the bore B which comprises this protrusion 1d is outlined. That is, the cutting tool (not shown) is rotated and moved in the axial direction of the bore B, and the bore B is basically processed. At the portion where the protrusion 1d is to be formed, the protruding length of the cutting tool is set. The bore B having the protrusions 1d can be easily opened by shrinking or remounting a cutting tool having a short overhang length and moving it to the deck surface 1b while rotating it.

  The protrusion 1d shown in FIG. 1a has a trapezoidal cross-sectional shape, but the cross-sectional shape of the protrusion may be an inverted triangular protrusion 1d 'as shown in FIG. 1b (the outline is tapered). Straight line), or a curved protrusion 1d ″ as shown in FIG. 1c. As a further modification of the protrusion 1d ″, the curved shape of the protrusion inside the bore B, 1/4 true It may be circular.

  Next, a thermal spray coating 2 as shown in FIG. 2 is formed on the prepared bore surface 1a of the cylinder block 1 using a thermal spraying apparatus (not shown) (second step). The formation of a sprayed coating here means the formation of a sprayed coating in the previous stage that is finally finished by honing.

  The spraying method on the bore surface 1a may be any spraying form among gas spraying, flame spraying, arc spraying, plasma spraying and the like. For example, the outline of the case of applying the arc spraying is as follows. That is, the cylinder block 1 is mounted and fixed on a mounting table (not shown), and a thermal spray gun mounted on a lifting device (not shown) via a rotation mechanism is advanced to the lowest part of the bore B. A current is applied to a power line (not shown), an arc is generated at the tip contact portion of the arc spray wire located at the tip of the spray gun, and the tip of the wire is melted by the heat to form droplets. By spraying atomized air to be ejected onto the droplets, the droplets are dispersed into fine spray particles. When the spray gun is rotated in this state and the inside of the bore B of the cylinder block 1 is raised at a predetermined speed, spray particles are sprayed on the bore surface 1a, which adheres to form the spray coating 2. As the thermal spray material, metal powder such as aluminum and molybdenum, alloy powder such as stellite alloy, chromium-iron alloy and nickel-chromium, ceramic powder such as alumina and zirconia, and the like can be used.

  When the thermal spray coating is formed on the bore surface 1a, the end region 1c facing the deck surface 1b of the bore B is chamfered using a chamfering device (not shown), as shown in FIG. The chamfered surface 1e is formed in the end region 1c.

  Here, the illustrated chamfered surface 1e is a processed surface that is chamfered so as to pass in the middle of the tapered portion below the ridge 1d.

  As an embodiment of the chamfered surface, in addition to the processed surface 1e, as shown in FIG. 4a, the chamfered surface 1f in which the protrusion 1d is completely removed in a tapered shape, or as shown in FIG. 4b. Alternatively, a form in which a part of the protrusion 1d is removed as the curved chamfered surface 1g may be used.

  In any of the chamfered surfaces 1e, 1f, and 1g, it is common that the thermal spray coating 2 does not face the deck surface 1b of the cylinder block 1 in the state after the chamfering.

  In this way, in the state after the chamfering process, by forming a state in which the sprayed coating 2 does not face the deck surface 1b of the cylinder block 1, it is applied at the time of the finishing process of the deck surface, which is a subsequent process. It is effectively eliminated that the thermal spray coating receives a direct pressing force from the processing tool or processing apparatus, and the thermal spray coating is peeled off from the bore surface by the pressing force.

  If the chamfered surface is formed in the end region 1c so as to pass through at least one of the inside of the ridge formed on the bore surface or its outline line, in the state after chamfering Thus, it is possible to obtain a state in which the sprayed coating does not face the deck surface. As a supplementary explanation, the chamfered surface 1f shown in FIG. 4a is a processed surface that passes through the lower end of the protrusion 1d.

  When chamfering is performed and chamfered surfaces 1e, 1f, and 1g as shown in FIGS. 3 and 4 are formed, finishing of the deck surface is performed, and then honing, which is the final finishing of the sprayed coating, is performed. Thus, the processing of the sprayed coating is completed.

[Experiment and results of verifying the presence or absence of peeling from the bore surface of the thermal spray coating when the processing method of the present invention is applied]
The inventors have obtained a processed product (comparative example) obtained by a conventional processing method, that is, a method of processing a thermal spray coating on the bore surface of a cylinder block where no protrusions exist in the end region of the bore, and the present invention. Each of the processed products (Examples) obtained by this processing method was prototyped, and the presence or absence of peeling of the sprayed coating during deck surface processing and the ratio when there was peeling off were verified. Table 1 shows an outline of processed products and processed parts common to the comparative examples and examples, and Table 2 shows processing conditions and verification results of the comparative examples and examples.

  Table 2 demonstrates that the thermal spray coating formed on the bore surface of the cylinder bore manufactured by the processing method of the present invention is not peeled off at the time of the deck surface processing, which is a subsequent process, and its effectiveness is Guaranteed.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 1a ... Bore surface, 1b ... Deck surface, 1c ... End region of bore, 1d, 1d ', 1d "... Projection, 1e, 1f, 1g ... Chamfered surface, 2 ... Thermal spray coating, B ... Boa

Claims (1)

A thermal spray coating processing method for processing a thermal spray coating on a bore surface of a bore established in a cylinder block,
A first cylinder block is provided which has an endless projecting ridge extending into the bore extending in an inner circumferential direction of the bore in a bore end region where the bore faces the deck surface of the cylinder block. Process,
A second step of forming a thermal spray coating on the bore surface;
A third step of chamfering so as to form a machining surface passing through at least a part of the ridge;
A method for processing a thermal spray coating, comprising: a fourth step of finishing the deck surface.

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