JP5087854B2 - Cylinder inner surface pre-spraying substrate processing method and cylinder inner surface pre-spraying pre-spraying shape - Google Patents

Description

The present invention relates to a pre-spraying substrate processing method for a cylindrical inner surface that forms the cylindrical inner surface on a rough surface before forming a sprayed coating on the inner surface of the cylinder, and a cylinder having a pre-sprayed surface treatment shape for the cylindrical inner surface.

  From the standpoint of improving the output, fuel consumption, exhaust performance of an internal combustion engine, and reducing the size and weight, the design requirements for eliminating the cylinder liner applied to the cylinder bore of the aluminum cylinder block are extremely high. Application of thermal spraying technology for forming a thermal spray coating on the inner surface of a cylinder bore is being promoted.

  When applying the above-mentioned spraying technology to the cylinder bore part, the spraying gun for spraying the spraying material is rotated while moving in the axial direction in the cylinder bore. Finish by grinding.

And, before forming the above-mentioned sprayed coating, for example, as described in the following Patent Document 1 proposed by the present applicant, by performing a base treatment to form the cylinder bore inner surface into a rough surface, Increases the adhesion of the thermal spray coating.
JP 2002-155350 A (paragraphs 0002, 0019)

  However, in spite of the above-described surface treatment being performed on the inner surface of the cylinder bore, the thermal spray coating is more easily peeled off at the axial end portion of the inner surface of the cylinder bore than at the central portion in the axial direction. Yes. This is because when the melting material adhering to the axial end of the inner surface of the cylinder bore after thermal spraying is solidified and condensed, a stress is generated such that this condensing part is pulled toward the axial center.

  Therefore, an object of the present invention is to suppress the stress generated when the melting material adhering to the axial end of the inner surface of the cylinder after spraying is solidified and condensed.

The present invention relates to a pre-spraying pre-spraying method for a cylindrical inner surface, in which a cylindrical surface is formed into a rough surface by using a cutting tool to form a threaded uneven portion before forming a thermal spray coating on the cylindrical inner surface. When forming the concavo-convex portion with the cutting tool, a fracture portion is formed at the tip of the convex portion in the screw-shaped concavo-convex portion, and the radial distance from the center of the cylinder of the bottom of the concave portion in the concavo-convex portion is as comparable axial center portion and axial end portion of the cylindrical inner surface, the convex portion in the uneven portion, the height from the bottom of the recess to the distal end, the axial direction than the axial central portion of the cylindrical inner surface The main feature is to make it high at the edge.

According to the present invention, when the molten material adhering at axial end portion is condensed and solidified, also the condensed portion occurs and stress that is pulled axially central portion, the condensation sites shaft The stress is countered by being caught by the concavo-convex portion at the end of the direction , and this stress can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an aluminum cylinder block 1 as a cylindrical member in the automobile engine according to the first embodiment of the present invention. A cylinder bore inner surface 5 serving as a cylinder inner surface of the cylinder bore 3 of the cylinder block 1 will be described later. The sprayed coating 30 (see FIG. 6) is formed by the method. After the thermal spray coating 30 is formed, finishing (here honing) is performed by a method described later. FIG. 1 shows a state in which the cylinder bore inner surface 5 is formed on the rough surface 9 as a base treatment before the thermal spray coating 30 is formed. By forming the rough surface 9, the adhesion degree of the thermal spray coating 30 to be formed thereafter increases. Reference numeral 11 denotes a crankcase.

  FIG. 2 is an enlarged cross-sectional view around the cylinder bore 3 of the cylinder block 1 shown in FIG. The cylinder bore inner surface 5 of the cylinder bore 3 is formed on the rough surface 9 as described above, and this rough surface 9 is the crankcase side end portion 13 and the cylinder head side end portion 15 which are axial ends of the cylinder bore 3. Is made rougher than the surface roughness of the central portion 17 in the axial direction.

  As shown in FIG. 3, the rough surface 9 is formed by a contouring process in which a cutting tool 23 is attached to the tip of a boring bar 21 attached to a main shaft 19 of a vertical machining center, and the main shaft 19 is eccentrically rotated. While moving in the feed direction A from the upper part to the lower part in the figure, threading is performed to form a screw-like uneven part.

  The above-described screw-shaped uneven portion is formed between the thread-shaped recess 25 (13a, 15a, 17a) that is directly cut by the cutting tool 23 and the recess 25 (13a, 15a, 17a). 13a, 15a, 17a) As a fractured part formed by breaking a part (top) of the tip (ridge) 26 (13b, 15b, 17b) at the time of threading by a cutting piece generated at the time of cutting Concave and convex portions 27 (13c, 15c, 17c) are provided.

  FIG. 4A shows a state in which the rough surface 9 composed of the concave portion 25 and the fine uneven portion 27 is formed by the cutting tool 23. FIG. 4B shows a state in which normal threading is performed with the tool 201 as a reference example.

  In FIG. 4 (b), the cutting tool 201 moves downward in the figure while rotating, and at this time, the chips 203 are discharged in the direction indicated by the arrow B. A normal threading process consisting of

  On the other hand, in FIG. 4A, the cutting tool 23 is adjacent to the currently formed recess 25 by the chip K discharged when the recess 25 corresponding to the valley 205 in FIG. 4B is formed. The top part 26a of the convex part (mountain part) 26 to be broken is broken, and thereby the fine uneven part 27 is formed.

  Here, in the tool 23 in FIG. 4A, the angle α1 with respect to the horizontal plane L of the surface 23a on the rear side in the tool feed direction is set to about 30 degrees as compared with the same angle α2 in FIG. At the same time, the angle β1 with respect to the horizontal plane L of the surface 23b on the front side in the tool feed direction is set to about 10 degrees, which is smaller than the same angle β2 in FIG. Accordingly, in FIG. 4A, the chip K discharged when forming the recess 25 is pressed against the convex portion 26 by the surface 23 a inclined to the rear side in the tool feeding direction, and the convex adjacent to the recess 25. The top portion 26 a of the portion 26 is broken to form a fine uneven portion 27.

  In the present embodiment, as described above, the surface roughness of the crankcase side end portion 13 and the cylinder head side end portion 15, which are axial ends of the cylinder bore 3, is determined from the surface roughness of the axial center portion 17. Although the surface roughness is rough, the difference in surface roughness is obtained by changing the feed speed in the feed direction A of the cutting tool 23 shown in FIG. 3 between the crankcase side end 13 and the cylinder head side end 15. This is achieved by making it faster than the direction center portion 17.

  Specifically, the rotational speed and the tool feed speed at the time of machining are set to 2000 rpm and 0.15 mm / rev at the axial direction central portion 17, respectively, and axial end portions (the crankcase side end portion 13 and the cylinder head side end portion). In 15), they are 2000 rpm and 0.25 mm / rev, respectively.

  By increasing the feed speed of the cutting tool 23 at the crankcase side end portion 13 and the cylinder head side end portion 15, the pitches P <b> 1 of the recesses 13 a and 15 a at these axial end portions are set at the axial center portion 17. It is larger than the pitch P2 of the recesses 17a.

Further, by increasing the feed speed of the cutting tool 23 so that the pitch P 1 of the recesses 1 3 a and 15 a is increased, the cutting in the axial direction is performed between the threading processes of the next circumference following the threading process of one round. The overlapping amount of the tool 23 is reduced, and the amount of breaking the top portion 26a of the convex portion 26 adjacent to the concave portion 25 after processing is reduced. As a result, as shown in FIG. 2, the height H1 of the convex portions 26 (13b, 15b) in the thread-like uneven portions of the crankcase side end portion 13 and the cylinder head side end portion 15 is It becomes higher than the height H2 of the convex portion 26 (17b).

  It should be noted that the distance (radius) from the center of the cylinder bore of the deepest part (bottom part) in the recesses 25 (13a, 15a) and the recesses 25 (17a) serving as the reference for the respective heights H1 and H2 is the same.

  After the rough surface 9 is formed on the cylinder bore inner surface 5 in this way, a thermal spray coating 30 is formed on the rough surface 9 as shown in FIG. The thermal spray coating 30 is formed to be substantially uniform with respect to the cylinder bore inner surface 5.

  The thermal spraying apparatus shown in FIG. 5 inserts a gas spray type thermal spray gun 31 into the center of the cylinder bore 3 and sprays a molten iron-based metal material as a thermal spray material from the thermal spray port 31a as a thermal spray 33 to form a cylinder bore. A thermal spray coating 30 is formed on the inner surface 5.

  The thermal spray gun 31 is supplied with a molten metal 37 of an iron-based metal material as a thermal spray material from a thermal feeder 35, and also has a fuel gas cylinder 39 storing fuel such as acetylene, propane or ethylene, and an oxygen cylinder storing oxygen. The fuel gas and oxygen are supplied from the pipe 41 through the pipes 43 and 45, respectively.

  The above-mentioned molten wire 37 is fed to the thermal spray gun 31 downward from the upper end of the molten wire feed hole 47 penetrating vertically in the central portion. Further, the fuel and oxygen are supplied to the gas guide channel 51 formed in the cylindrical portion 49 outside the melt feed hole 47 so as to penetrate in the vertical direction. The supplied mixed gas of fuel and oxygen flows out from the lower end opening 51a in FIG. 5 of the gas guide channel 51 and is ignited to form a combustion flame 53.

  An atomizing air flow channel 55 is provided on the outer peripheral side of the cylindrical portion 49, and an accelerator air flow channel 61 formed between the cylindrical partition wall 57 and the outer wall 59 is provided on the outer peripheral side thereof. It is.

  The atomizing air flowing through the atomizing air flow channel 55 sends the heat of the combustion flame 53 forward (downward in FIG. 5) to cool the peripheral portion, and sends the molten wire 37 forward. On the other hand, the accelerator air flowing through the accelerator air flow path 61 sends the molten wire 37 sent forward and melted as the droplet 33 toward the cylinder bore inner surface 5 so as to intersect the feed direction, and sprayed onto the cylinder bore inner surface 5. A film 30 is formed.

  Atomized air is supplied to the atomized air flow channel 55 from an atomized air supply source 67 through an air supply pipe 71 provided with a pressure reducing valve 69. On the other hand, accelerator air is supplied from the accelerator air supply source 73 to the accelerator air flow channel 61 through an air supply pipe 79 provided with a pressure reducing valve 75 and a micro mist filter 77.

  The partition wall 57 between the atomizing air flow channel 55 and the accelerator air flow channel 61 is provided with a rotating cylinder portion 83 that can rotate with respect to the outer wall 59 via a bearing 81 at the lower end portion in FIG. Yes. A rotating blade 85 located in the accelerator air flow path 61 is provided on the outer periphery of the upper portion of the rotating cylinder portion 83. When the accelerator air flowing through the accelerator air flow path 61 acts on the rotary blade 85, the rotary cylinder portion 83 rotates.

  A tip member 87 that rotates integrally with the rotary cylinder 83 is fixed to the tip (lower end) surface 83 a of the rotary cylinder 83. A protrusion 91 having an ejection flow path 89 communicating with the accelerator air flow path 61 through the bearing 81 is provided at a part of the peripheral edge of the distal end member 87, and the droplet 33 is formed at the distal end of the ejection flow path 89. The above-described thermal spraying port 31a is provided for jetting.

  The thermal spray coating 30 is formed on almost the entire area of the cylinder bore inner surface 5 by reciprocating the thermal spray gun 31 in the axial direction of the cylinder bore 3 while the tip member 87 having the thermal spray port 31a rotates integrally with the rotary cylinder portion 83. .

  The sprayed coating 30 formed in this way has a rough surface 9 processed as a base treatment before spraying at the axial end of the cylinder bore 5, that is, the crankcase side end 13 and the cylinder head side end 15 in the axial direction. Since the surface roughness is made rougher than the central portion 17, when the melting material adhering to the axial end portion is solidified and condensed, there is a stress that pulls the condensed portion toward the axial central portion 17 side. Even if it occurs, the condensing part is caught by the part having a rough surface to counter the stress, and this stress can be suppressed. As a result, the thermal spray coating 30 can be prevented from peeling off at the axial end. .

  The rough surface 9 of the cylinder bore inner surface 5 forms a screw-like uneven portion using the cutting tool 23, and the height of the convex portion 26 in the screw-like uneven portion is set to the center in the axial direction of the cylinder bore inner surface 5. Since the axial end portion (crankcase side end portion 13 and cylinder head side end portion 15) is higher than the portion 17, the volume of the recess 25 (13a, 15a) at the axial end portion is set to the axial central portion 17. Accordingly, the amount of the thermal spray material that enters the recesses 25 (13a, 15a) increases correspondingly, and the above-described stress can be more reliably suppressed.

  Furthermore, since the fine uneven part 27 is formed at the tip of the convex part 26 in the above-described screw-like uneven part, the adhesion degree of the thermal spray coating 30 is increased, and the thermal spray coating 30 can be reliably prevented from peeling off.

  After the thermal spray coating 30 is formed as shown in FIG. 6, as shown in FIG. 7, unnecessary portions of the cylinder bore 3 near the crankcase side end 13 and the cylinder head side end 15 (the piston (not shown) does not slide). The part) is ground and removed together with the thermal spray coating 30. At this time, chamfering is performed by forming tapered surfaces 93 and 95 having a larger diameter toward the end in the axial direction.

  When carrying out the above chamfering process, the above-described stress of the thermal spray coating 30 in the vicinity of the crankcase side end portion 13 and the cylinder head side end portion 15 is suppressed, so that the thermal spray coating 30 is also peeled off during the chamfering processing. Therefore, it is possible to reduce the processing time by increasing the processing speed at the time of chamfering processing as compared with the conventional method, thereby contributing to a reduction in processing cost.

  Finally, as shown in FIG. 8, honing is performed with the surface of the thermal spray coating 30 as a finishing process. FIG. 8 is a cross-sectional view showing a state where the honing process is performed on the cylinder block 1 by the honing tool 105. On the outer periphery of the honing head 107 in the honing tool 105, four grindstones 109 made of abrasive grains such as diamond are attached at equal intervals in the circumferential direction.

  The honing head 107 is provided with expansion means for expanding the grindstone 109 outward in the diametrical direction. At the time of processing, the grindstone 109 is expanded and pressed against the cylinder bore inner surface 5 with a predetermined pressure.

  The honing tool 105 is rotated and reciprocated in the axial direction to grind the surface of the thermal spray coating 30 and perform honing. Thereby, the process with respect to the cylinder bore inner surface 5 is completed. In the honing process, the roughing process and the finishing process are sequentially performed by changing the grain size of the grindstone to be used.

  FIG. 9 is a cross-sectional view of the cylinder block 1A corresponding to FIG. 2 showing a second embodiment of the present invention, and after forming the rough surface 9 and before forming the thermal spray coating 30A (see FIG. 10). Shows the state. In the second embodiment, a groove 97 larger than the recesses 13a and 15a described above is provided at the axially outer end of the crankcase side end 13 and the cylinder head side end 15 which are axial ends of the cylinder bore 3A. 99 are formed. The other structure is the same as that shown in FIG.

  The grooves 97 and 99 have a wide axial width on the cylinder bore inner surface 5A, and are provided with flat bottom surface portions 97a and 99a extending in the coaxial direction at the bottom, and are formed at least for one round. The grooves 97 and 99 are processed using a tool different from the cutting tool 23 shown in FIG. 3, and the processing conditions at that time are a rotational speed of 2000 rpm and a tool feed speed of 0.1 mm. / Rev.

  FIG. 10 shows a state after forming the thermal spray coating 30A and before chamfering. The chamfered portion is indicated by a two-dot chain line. In the second embodiment, the thermal spray coating 30A is formed by spraying the thermal spray material into the grooves 97 and 99, so that the grooves 97 and 99 serve as weirs and spray the portions where the grooves 97 and 99 are formed. A depression 30 a is formed in the film 30.

  By forming the depression 30a, the thermal spray coating 30A is separated from the thermal spray coating 30b on the axial central portion 17 side and the thermal spray coatings 30c and 30d on the axial end portion side with the depression 30a as a boundary. It becomes a shape. As a result, the stress generated so that the thermal spray coatings 30c and 30d at the axial end portions are pulled toward the axial central portion 17 side due to solidification condensation of the thermal spray material after thermal spraying is suppressed, and the axial direction from the grooves 97 and 99 is reduced. Separation of the thermal spray coating 30b on the center portion 17 side can be suppressed.

  In addition, the above-mentioned hollow 30a is further greatly depressed, and finally the thermal spray coating 30b at the axial center portion 17 and the thermal spray coating 30c, 30d at the axial end portion are completely divided by the grooves 97, 99 as a boundary. In such a case, peeling of the thermal spray coating 30b on the axial center portion 17 side from the grooves 97 and 99 can be more reliably suppressed.

  Thus, in order to completely divide the thermal spray coating 30b at the axial center portion 17 and the thermal spray coatings 30c, 30d at the axial end portion, the axial width of the cylinder bore inner surface 5 is set at a portion having a rough surface roughness. The bottom portions 7a and 99a that are wider than the recesses 13a and 15a and extend in the axial direction of the cylinder bore inner surface 5 are formed at the bottoms of the grooves 97 and 99, so that the inflow amount of the thermal spray material into the grooves 97 and 99 It is good to increase.

  After the formation of the thermal spray coating 30A, as in the case shown in FIG. 7, unnecessary portions near the crankcase side end 13 and the cylinder head side end 15 in the cylinder bore 3 (portions where a piston (not shown) does not slide). Is removed together with the sprayed coating 30A. At this time, chamfering is performed by forming tapered surfaces 93A and 95A having a larger diameter at the end in the axial direction.

  When carrying out the above chamfering process, the above-described stress of the thermal spray coating 30A in the vicinity of the crankcase side end 13 and the cylinder head side end 15 is suppressed, so that the thermal spray coating 30A is also peeled off during the chamfering process. Therefore, it is possible to reduce the processing time by increasing the processing speed at the time of chamfering processing as compared with the conventional method, thereby contributing to a reduction in processing cost.

It is sectional drawing of the cylinder block concerning the 1st Embodiment of this invention. FIG. 2 is an enlarged cross-sectional view around a cylinder bore of the cylinder block shown in FIG. 1. It is sectional drawing which shows the state which is performing the surface treatment process with respect to the cylinder block of FIG. (A) is explanatory drawing which shows the state which is performing the ground treatment of FIG. 3 with a tool and a chip, (b) is explanatory drawing which shows the normal thread cutting process by a tool. It is a whole block diagram which shows the outline of the thermal spraying apparatus for forming a thermal spray coating, after roughening the cylinder bore inner surface of the cylinder block of FIG. It is sectional drawing of the cylinder block which shows the state in which the sprayed coating was formed after the base-treatment process of FIG. It is sectional drawing of the cylinder block which shows the state which performed the chamfering process with respect to the axial direction edge part of a cylinder bore after spraying coating formation of FIG. It is sectional drawing of the cylinder block which shows the state which is performing the honing process after the chamfering process of FIG. It is sectional drawing of the cylinder block equivalent to FIG. 2 which shows the 2nd Embodiment of this invention. It is sectional drawing of the cylinder block which shows the state which formed the sprayed coating after the base-treatment process of FIG.

Explanation of symbols

3,3A Cylinder bore 5,5A Cylinder bore inner surface (cylindrical inner surface)
9 Rough surface 13 Cylinder bore crankcase side end (axial end)
15 Cylinder bore end of cylinder bore (end in axial direction)
17 Cylinder bore axial center portion 26 (13b, 15b, 17b) Threaded uneven portion convex portion 27 (13c, 15c, 17c) Fine uneven portion at the tip of the convex portion (rupture portion)
30, 3A Thermal sprayed coating 97, 99 groove 97a, 99a groove bottom surface

Claims (10)

Before forming a thermal spray coating on the cylindrical inner surface, the cylindrical tool is formed by forming a threaded uneven portion on the cylindrical inner surface using a cutting tool to form a rough surface. When forming the concavo-convex portion by the above , a rupture portion is formed at the tip of the convex portion in the screw-shaped concavo-convex portion, and the radial distance from the center of the cylinder of the bottom portion of the concave portion in the concavo-convex portion is defined as the axis of the inner surface of the cylinder. as comparable with direction central portion and the axial end portion of the convex portion in the uneven portion, the height from the bottom of the recess to the distal end, higher at the axial end portion than the central portion in the axial direction of the cylindrical inner surface A pre-spraying substrate processing method for a cylindrical inner surface, characterized in that: 2. The pre-spraying pre-spraying method for a cylindrical inner surface according to claim 1, wherein a pitch of the concave portions in the concave and convex portions is larger at an axial end than an axial central portion of the cylindrical inner surface. The end of Risarani axially outer O axial end portion of the cylindrical inner surface, spraying the cylindrical inner surface according to claim 1 or 2, characterized in that to form the larger grooves than the recess of the axial end Pre-ground processing method. 4. The pre-spraying pre-spraying method for a cylindrical inner surface according to claim 3 , wherein the groove larger than the concave portion has a width in the axial direction of the cylindrical inner surface wider than that of the concave portion at the axial end portion . 5. The pre-spraying substrate surface processing method for a cylindrical inner surface according to claim 3 , wherein a bottom surface portion extending in the axial direction of the cylindrical inner surface is formed at a bottom portion of a groove larger than the concave portion. Before forming the thermal spray coating on the cylindrical inner surface, the cylindrical inner surface is formed as a rough surface by forming a screw-like uneven portion with a cutting tool to form the cylindrical inner surface as a pre-spraying base processing. In the cylinder having , at the tip of the convex portion in the screw-shaped concave and convex portion, there is a fracture portion formed when forming the concave and convex portion by the cutting tool , and from the center of the cylinder at the bottom of the concave portion in the concave and convex portion The radial distance is the same at the axial center and the axial end of the cylindrical inner surface, and the height of the convex portion of the concave and convex portion from the bottom to the tip of the concave portion is the axis of the cylindrical inner surface. A cylinder having a pre-spraying surface treatment shape on the inner surface of the cylinder, characterized by being higher at the axial end than at the center in the direction. The cylinder having a pre-sprayed surface treatment shape on a cylindrical inner surface according to claim 6, wherein a pitch of the concave portions in the concave and convex portions is larger at an axial end than an axial central portion of the cylindrical inner surface. 8. The cylindrical inner surface according to claim 6, wherein a groove larger than a concave portion of the axial end portion is formed at an end portion on the axially outer side of the axial inner end portion of the cylindrical inner surface. A cylinder with a pre-sprayed surface treatment. 9. A cylinder having a pre-sprayed surface treatment shape on a cylindrical inner surface according to claim 8, wherein the groove larger than the concave portion has an axial width wider than that of the concave portion at the axial end portion of the cylindrical inner surface. . 10. The cylinder having a pretreatment surface shape before spraying on the inner surface of the cylinder according to claim 8, wherein a bottom surface portion extending in the axial direction of the inner surface of the cylinder is formed at the bottom of the groove larger than the recess.

Images