JP4617806B2 - Thermal spray pretreatment method - Google Patents

Description

The present invention relates to a thermal spraying preprocessing method for forming the substrate surface before the formation of the thermal spray coating to the roughened 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 cylindrical recess is formed on the inner surface of a cylinder bore by forming a screw-like recess, and a projection between the recesses 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.

  Then, this invention aims at enabling it to roughen the base-material surface in a short time.

The present invention provides a thermal spraying pretreatment method for forming a rough surface of a base material before forming a sprayed coating, and performing a broaching process on the base material surface to form a concavo-convex portion. When forming a fractured surface by breaking the surface, the most important feature is to break the tip of the convex portion by rubbing with a wire brush .

According to the present invention, after forming the concavo-convex portion by performing broaching on the surface of the base material, the convex portion is broken to form the fractured surface. The surface of the material can be roughened in a short time.
Further, the fracture surface is stabilized by rubbing the tip of the convex portion of the concave and convex portion with a wire brush.

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

  FIG. 1 is a cross-sectional view showing a state in which broaching is performed in a thermal spraying pretreatment method according to an embodiment of the present invention. Here, for example, a cylinder bore inner surface 3 which is a cylindrical inner surface in the cylinder block 1 of the engine is used as the base material 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 the above-described cylinder bore inner surface 3 is roughened, a broach tool 5 as shown in an enlarged view in FIG. 2 is used. FIG. 2A is a front view of the broach tool, and FIG. 2B is a plan view thereof.

  This broaching tool 5 is connected to a broaching blade support 7 mounted on a main shaft 6 of a broaching machine (not shown) from the lower side in FIG. A second roughing broaching blade 11 having a larger diameter than the first roughing broaching blade 9 and a finishing broaching blade 13 having a larger diameter than the second roughing broaching blade 11 are sequentially attached.

  Next, the operation will be described. By driving a broaching machine (not shown), the broaching tool 5 described above is inserted into the cylinder bore from above the cylinder block 1 as shown in FIG. The broach blade 11 sequentially performs broaching by roughing on the cylinder bore inner surface 3, and then the finishing broaching blade 13 performs finish broaching.

  FIG. 3 is a perspective view showing the shape of the cylinder bore inner surface 3 after broaching as described above, in which a concavo-convex portion 19 including a concave portion 15 and a convex portion 17 extending in the axial direction (vertical direction in FIG. 3) of the cylinder bore is formed. ing.

  FIG. 4A is a perspective view showing a part of the uneven portion 19 in an enlarged manner. After broaching, after the broach tool 5 is pulled out from the cylinder bore, as shown in FIG. 21 is inserted into the cylinder bore while being rotated. The wire brush 21 is attached to a main shaft 23 of a drive device (not shown) and includes a shaft portion 25 and a number of metal pin-like members 27 provided on the outer peripheral surface of the shaft portion 25.

  By inserting the wire brush 21 into the cylinder bore while rotating the wire brush 21 by driving the driving device (not shown), the cylinder bore inner surface 3 breaks the tip of the convex portion 17 in the concave and convex portion 19 from the state of FIG. Thus, the fracture surface 29 as shown in FIG. 4B is formed.

  As a result, the cylinder bore inner surface 3 can be formed into a desired rough surface shape. The roughening process for the cylinder bore inner surface 3 is performed by broaching to form the concavo-convex part 19 and then breaking the convex part 17 to form the fracture surface 29. Compared with the case where it does, it can carry out in a short time and can improve processing efficiency.

  In addition, the roughened surface shape obtained is stable because the wire brush 21 is used for the fractured surface 29 obtained by breaking the convex part 17 as compared with the case where the convex part is broken by a cutting piece during boring. In addition, the tool can be prevented from being damaged by a cast hole as in the case of boring, and the tool life can be extended.

  Further, since the broach tool 5 is provided with first and second roughing broaching blades 11 and 13 in addition to the finishing broaching blade 13, rough boring and fine boring of the cylinder bore prior to roughening. The number of processes can be reduced.

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

  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. 6 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 51 a in FIG. 6 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. 6) 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 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 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 state which is performing the broaching in the thermal spraying pretreatment method concerning one Embodiment of this invention. (A) is the front view of the broach tool in embodiment of FIG. 1, (b) is the top view. It is a perspective view which shows the shape of the cylinder bore inner surface after broaching by embodiment of FIG. (A) is a perspective view which expands and shows a part of uneven part of the cylinder bore inner surface after broaching, (b) is a perspective view which shows the state which removed the convex part of the uneven part with the wire brush after broaching. It is sectional drawing which shows the state currently processed with the wire brush after broaching. 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 (base material surface, cylindrical inner surface)
DESCRIPTION OF SYMBOLS 5 Broach tool 9 1st roughing broaching blade 11 2nd roughing broaching blade 13 Finishing broaching blade 17 Convex part 19 Concave part 21 Wire brush 29 Fracture surface 32 Thermal spray coating

Claims (3)

  In the thermal spraying pretreatment method for forming the base material surface before forming the spray coating on a rough surface, the base material surface is broached to form an uneven portion, and the tip of the convex portion in the uneven portion is destroyed. A thermal spraying pretreatment method characterized in that, when forming a fractured surface, the tip of the convex portion is destroyed by rubbing with a wire brush.   The substrate surface is a cylindrical inner surface, the broaching process is performed on the cylindrical inner surface to form the uneven portion, and the tip of the convex portion in the uneven portion is broken by rotating the wire brush. The thermal spraying pretreatment method according to claim 1.   The broaching tool used when performing the broaching is provided with a roughing broaching blade and a finishing broaching blade along the axial direction, respectively, and the roughing broaching blade by the roughing broaching blade is moved by the axial movement of the broaching tool. The thermal spraying pretreatment method according to claim 1, wherein the finishing process is continuously performed by the finishing broaching blade following the processing.

Images