JP4507795B2 - Thermal spray pretreatment method - Google Patents

Description

The present invention relates to a thermal spraying pretreatment method for forming a cylindrical inner surface before forming a thermal spray coating on a rough surface.

  When forming a thermal spray coating on the cylinder bore inner surface of a linerless aluminum cylinder block, which is effective for reducing the weight of an automobile engine and dealing with exhaust treatment, as a pre-process, the inner surface of the cylinder bore is improved for the purpose of improving the adhesion of the thermal spray coating. It is necessary to form on a rough surface.

For example, in Patent Document 1 below, a threaded concave portion is formed by boring a cylinder bore inner surface, and a convex portion between the concave portions is removed by a cutting piece generated at this time. Forming a fracture surface.
JP 2002-155350 A

  However, the conventional thermal spraying pretreatment method described above has a problem that it takes time for boring and the machining efficiency is lowered.

  Therefore, an object of the present invention is to enable the cylindrical inner surface to be roughened in a short time.

  The present invention provides a thermal spraying pretreatment method in which a cylindrical inner surface before forming a sprayed coating is formed into a rough surface, and a tool is inserted into the cylinder, and the blade portion of the tool is pressed against the cylindrical inner surface while the insertion is performed. When moving in the direction, the most important feature is that the cylinder is elastically deformed by the insertion resistance and vibrates, and by this vibration, the surface of the cylindrical inner surface is peeled off to form a rough surface.

  According to the present invention, the blade portion of the tool to be inserted into the cylinder is vibrated when being moved in the insertion direction while being pressed against the inner surface of the cylinder, and by this vibration, the surface of the inner surface of the cylinder is stripped to form a rough surface. Therefore, the inner surface of the cylinder can be roughened in a shorter time than in the case of boring.

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

  FIG. 1 is a cross-sectional view showing a thermal spraying pretreatment method according to the first embodiment of the present invention. Here, for example, a cylinder bore inner surface 3 which is a cylinder inner surface in the cylinder block 1 of the engine is used as the cylinder inner surface before the thermal spray coating is formed. The cylinder block 1 described above is made of die-casting made of an aluminum alloy (ADC12 material), and the cylinder bore inner surface 3 is processed with a certain accuracy. After the cylinder bore inner surface 3 is formed into a rough surface, a spraying material made of an iron-based material is sprayed onto the cylinder bore inner surface 3 to form a sprayed coating.

  When roughening the above-described cylinder bore inner surface 3, a tool 5 as shown in an enlarged view in FIG. 2 is used. 2A is a front view of the tool 5, and FIG. 2B is a bottom view of FIG. 2A.

  The tool 5 includes a support portion 9 attached to a spindle 7 of a processing apparatus (not shown), a disk portion 11 as a tool body located at the lower end of the support portion 9, and an equal interval around the disk portion 11 along its circumferential direction. The chip 13 is made of cemented carbide as the four blade portions detachably attached to the positions.

  As shown in FIG. 2 (b), each tip 13 is formed in a convex curved shape in which the outer peripheral edge 13a substantially coincides with the concave curved surface of the cylinder bore inner surface 3, and the diameter of a circle P including each outer peripheral edge 13a. Is slightly larger than the inner diameter of the cylinder bore before processing by the tool 5.

  The main shaft 7 of the processing apparatus moves in the axial direction and sequentially rotates every predetermined angle. As shown in FIG. 2B, the predetermined angle is an angle smaller than an angle θ formed by two straight lines connecting the circumferential ends A and B of the tip 13 and the center Q of the tool 5.

  Next, the operation will be described. As shown in FIG. 1, the tool 5 is inserted into the cylinder bore from above the cylinder block 1 by driving a machining apparatus (not shown), so that the outer peripheral edge 13 a of each chip 13 is inserted while being pressed against the cylinder bore inner surface 3. By moving in the direction, the chip 13 generates minute so-called chatter vibration in the vertical direction in FIG. 1, and this vibration causes the surface of the cylinder bore inner surface 3 to be peeled off as shown in FIG. The rough surface 3a is formed.

  At this time, it is sufficient that at least three tips 13 are provided in the circumferential direction of the disk portion 11, and thereby, at least three tips 13 perform a machining operation at the same time, thereby avoiding a reduction in hole diameter due to tool escape, When the cutting (insertion) resistance is generated, the tip 13 is elastically deformed and the chatter vibration is generated.

  When the tool 5 is moved to the lower end in the axial direction of the cylinder bore inner surface 3 in FIG. 1 and the width of each chip 13 is formed on the rough surface 3a, the tool 5 is moved upward and pulled out from the cylinder bore. Thereafter, the tool 5 is rotated by the predetermined angle, that is, an angle smaller than the angle θ shown in FIG. 2B, and in this state, the tool 5 is moved downward again in the same manner as described above to move into the cylinder bore. A rough surface that is continuous in the circumferential direction is formed in the same manner with respect to the processed rough surface 3a.

  In this way, the entire rough surface 3a of the cylinder bore is roughened by repeatedly forming the rough surface 3a along the circumferential direction substantially by the width of the chip 13. After the roughening, a thermal spray coating made of an iron-based material is sprayed onto the cylinder bore inner surface 3 by a method described later to form a thermal spray coating.

  According to the above-described embodiment, the tip 13 of the tool 3 to be inserted into the cylinder bore is vibrated when being moved in the insertion direction while being pressed against the cylinder bore inner surface 3, and the surface of the cylinder bore inner surface 3 is peeled off by this vibration. Since the surface is formed, the cylinder bore inner surface 3 can be roughened in a shorter time than in the case of boring, which can contribute to the improvement of productivity.

  In addition, since the outer peripheral edge 13a of the tip 13 has a curved shape that substantially matches the curved surface of the cylinder bore inner surface 3, the curve R can be made relatively large. The chip 13 can be prevented from being damaged by the cast hole as in the case of machining, and the tool life can be extended.

  Moreover, since the rough surface shape obtained also stabilizes as a whole compared with the case where a convex part is destroyed with a cutting piece at the time of a boring process, the adhesive force of the sprayed coating formed after that increases.

  FIG. 4 shows a tool 50 corresponding to FIG. 2 according to the second embodiment of the present invention. The tool 50 is provided with a plurality of (here, five) disk portions 11 (11A, 11B, 11C, 11D, and 11E) on a support portion 90 that is mounted on the spindle 7 of the above-described processing apparatus. Around the periphery, chips 13 (13A, 13B, 13C, 13D, 13E) as four blade portions are detachably attached at equal intervals along the circumferential direction.

  Then, the four chips 13 of each disk portion 11 are sequentially shifted in the circumferential direction so that the adjacent ones of the disk portions 11 partially overlap in plan view as shown in FIG. All chips 13 are arranged continuously along the circumferential direction.

  Also in the second embodiment, as in the first embodiment shown in FIG. 1, each chip is inserted by inserting a tool 50 into the cylinder bore from above the cylinder block 1 by driving a machining apparatus (not shown). As the outer peripheral edge 13a of 13 moves in the insertion direction while being pressed against the cylinder bore inner surface 3, the tip 13 is elastically deformed by cutting (insertion) resistance, and minute chatter vibration is generated in the insertion direction. In the same manner as shown in FIG. 3, the rough surface 3a is formed by peeling off the surface of the cylinder bore inner surface 3.

  For this reason, the second embodiment has the same effect as the first embodiment, and all the chips 13 (13A, 13B, 13C, 13D, and 13E) are rotated as shown in FIG. Since the tool 50 is continuously arranged along the direction, the tool 50 can be roughened with respect to the entire inner surface 3 of the cylinder bore only by performing an insertion operation once in the cylinder bore. Can be further shortened.

  The cylindrical surface described above is not limited to the cylinder bore inner surface 3 in the cylinder block of the engine, and the present invention can be applied to other cylindrical inner surfaces.

  Moreover, about the rough surface shape of the cylinder bore inner surface 3 processed by thermal spraying pretreatment as described above, the shape is measured by a contact-type shape measuring machine such as a laser and the accuracy is guaranteed.

  FIG. 5 is an overall configuration diagram showing an outline of a thermal spraying apparatus for forming a thermal spray coating after roughening the cylinder bore inner surface 3. In this thermal spraying apparatus, a gas spray type spray gun 31 is inserted into the center of the cylinder bore, and an iron-based metal material melted as a thermal spraying material is sprayed from the thermal spray port 31a as a spray 33 to spray onto the inner surface 3 of the cylinder bore. A film 32 is formed.

  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 fed forward and melted as the droplet 33 toward the cylinder bore inner surface 3 so as to intersect the feed direction, and sprayed onto the cylinder bore inner surface 3. A film 32 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 is rotatable 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 tip member 87 including the spray port 31a rotates integrally with the rotary cylinder portion 83 while moving the spray gun 31 in the axial direction of the cylinder bore, so that the spray coating 32 is formed on almost the entire area of the cylinder bore inner surface 3.

It is sectional drawing which shows the thermal spraying pretreatment method concerning the 1st Embodiment of this invention. (A) is the front view of the tool in embodiment of FIG. 1, (b) is a bottom view of (a). It is an operation explanatory diagram according to the thermal spray preprocessing method of Fig. (A) is a front view of a tool corresponding to FIG. 2 according to the second embodiment of the present invention, and (b) is a bottom view of (a). It is a whole block diagram which shows the outline of a thermal spraying apparatus.

Explanation of symbols

1 Cylinder block 3 Cylinder bore inner surface (cylindrical inner surface)
3a Rough surface 5 Tool 11 (11A, 11B, 11C, 11D, 11E) Disk part (tool body)
13 (13A, 13B, 13C, 13D, 13E) Tip (blade)
13a Outer peripheral edge of chip 32 Thermal spray coating P Circle including outer peripheral edge of chip

Claims (4)

  In the thermal spraying pretreatment method for forming a cylindrical inner surface before forming a thermal spray coating on a rough surface, a tool is inserted into the cylinder, and a blade portion of the tool moves in the insertion direction while being pressed against the inner surface of the cylinder. In this case, the thermal spraying pretreatment method is characterized by elastically deforming and vibrating due to insertion resistance, and peeling the surface of the inner surface of the cylinder by the vibration to form a rough surface.   The tool is provided with a plurality of blade portions along the circumferential direction on the outer peripheral portion of the tool body, and the diameter of a circle including the outer peripheral edge of each blade portion is made larger than the inner diameter of the cylindrical inner surface. The thermal spraying pretreatment method according to claim 1.   The thermal spraying pretreatment method according to claim 2, wherein at least three blade portions are provided along the circumferential direction.   A plurality of blade portions provided along the circumferential direction are inserted into the tool body so that the blade portion is continuously arranged along the circumferential direction when the tool is viewed from the insertion direction. The thermal spraying pretreatment method according to claim 2, wherein a plurality of the thermal spray pretreatment methods are provided along the direction.

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