JP6260253B2 - Thermal spraying method - Google Patents

Description

The present invention relates to a thermal spray how to form a sprayed coating on the inner surface of the hole of the work.

  There is known a thermal spraying technique in which a thermal spraying material such as metal or ceramic is sprayed on the inner surface of a circular hole such as the inner surface of a cylinder bore of a cylinder block in an automobile engine (see Non-Patent Document 1 below). .

Journal of the Japan Institute of Metals Vol. 71 No. 3 (2007) 354-360

  As thermal spraying methods for forming such a thermal spray coating, plasma spraying and arc thermal spraying are the mainstreams, but in either method, it is an issue to increase the adhesion of the thermal spray coating to the surface to be sprayed.

  Then, this invention aims at improving the adhesive force of the sprayed coating with respect to a to-be-sprayed surface.

The present invention, in forming a thermal spray coating in succession to the inner surface of the plurality of holes formed in the workpiece, at least then the inner surface of the spray holes relative to the holes that are sprayed by spray gun, spray gun It heats by another heat source .

According to the present invention, by heating at least the inner surface of the hole to be sprayed next, the temperature decrease of the inner surface of the hole to be sprayed next can be suppressed. You can increase your power.

FIG. 1 is an overall configuration diagram of a basic thermal spraying apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view showing a cylinder block and a spray gun in the thermal spray apparatus of FIG. FIG. 3 is a cross-sectional view showing a state where thermal spraying is performed on the inner surface of the cylinder bore by the thermal spray gun of FIG. FIG. 4 is an operation explanatory view showing a state in which an air flow is generated in the thermal spray booth in the thermal spray apparatus of FIG. FIG. 5 is a graph showing temperature changes of the first cylinder bore and the fourth cylinder bore when the plurality of cylinder bores are sequentially sprayed in the spraying booth of FIG. 1 after preheating the cylinder block. . FIG. 6 is a cross-sectional view showing the thermal spraying method according to the first embodiment. FIG. 7 is a cross-sectional view showing a thermal spraying method according to the second embodiment. FIG. 8 is an operation explanatory view showing the thermal spraying method according to the third embodiment in the order of (a), (b), and (c). FIG. 9 is an operation explanatory view showing the thermal spraying method according to the fourth embodiment in the order of (a), (b), and (c).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the thermal spraying apparatus according to the first embodiment of the present invention is formed on the inner surface of a cylinder bore 3 (3A, 3B, 3C, 3D) in a cylinder block 1 of an in-line four-cylinder engine for automobiles, for example. On the other hand, a sprayed coating is formed. Here, the cylinder block 1 constitutes a workpiece, and the cylinder bore 3 constitutes a hole of the workpiece. That is, a plurality of cylinder bores 3 that are holes are formed in the cylinder block 1 that is a workpiece.

  When forming a spray coating on the inner surface of the cylinder bore 3, a spray gun 5 is used. As shown in FIG. 3, the spray gun 5 includes two wires 9 and 11, which are materials for spraying, in the nozzle portion 7, as shown in the nozzle portion 7 formed on the side of the tip (lower end) of the spray gun 5. Wire insertion holes 7a and 7b are provided.

  The wire insertion holes 7a and 7b include parallel portions 7a1 and 7b1 that are parallel to each other, and inclined portions 7a2 and 7b2 that are spaced from each other toward the distal end side of the nozzle portion 7 from the distal ends of the parallel portions 7a1 and 7b1. And. The inclined portions 7a2 and 7b2 are inclined in front of the tip surface 7c of the nozzle portion 7 (on the left side in FIG. 3) such that respective extension lines extending in the inclination direction of the inclined portions 7a2 and 7b2 intersect each other.

  Here, when one of the wires 9 is a plus (+) electrode and the other wire 11 is a minus (-) electrode, and a voltage is applied between the electrodes of the wires 9, 11, the above-described inclined portions 7a2, 7b2 are extended. At the intersection on the line, a discharge arc 13 is generated between the electrodes. The two wires 9 and 11 are melted by the heat energy of the discharge arc 13. That is, the thermal spraying apparatus in this embodiment is an arc thermal spraying apparatus using a discharge arc.

  At that time, by flowing the atomizing gas into the atomizing gas passage 7d provided in the center of the nozzle portion 7, the melted material of the wires 9 and 11 is sprayed forward 15 and scattered forward, and is applied to the inner surface of the cylinder bore 3. The thermal spray coating 17 is formed by adhering. The atomizing gas passage 7d has a tapered shape such that the cross section of the passage becomes smaller toward the tip side, and the discharge port 7d1 at the tip is formed with an intersection portion on each extension line of the inclined portions 7a2 and 7b2, that is, the discharge arc 13. It is oriented to the position.

  When forming the thermal spray coating 17, the thermal spray gun 5 moves in the axial direction of the cylinder bore 3 as indicated by an arrow B while rotating as indicated by the arrow A shown in FIG. As a result, the thermal spray coating 17 can be formed on almost the entire inner surface of the cylinder bore 3. Note that the inner surface of the cylinder bore 3 is formed as a concavo-convex shape portion 3 a as shown in FIG. 3 in order to increase the adhesion of the thermal spray coating 17. The uneven portion 3a is formed by, for example, threading.

  Here, in this embodiment, the thermal spraying operation is performed in a state where the cylinder block 1 is accommodated in the thermal spray booth 19 as shown in FIG. At that time, air as a gas is circulated in the spraying booth 19 in order to collect extraneous spray particles and soot and other foreign matters generated during spraying to collect the dust. The thermal spray booth 19 has a rectangular parallelepiped or cubic box shape, and is provided with an intake pipe 21 on one side surface and a lower exhaust pipe 23 on a bottom surface. A side exhaust pipe 25 is provided on the side surface opposite to the side surface on which the intake pipe 21 is provided, and an upper exhaust pipe 27 is provided on the upper surface. In addition, the cylinder block 1 shall be supported by the support member which is not shown in figure in the thermal spray booth 19, for example, the outer peripheral part of a lower part.

  The above-described lower exhaust pipe 23 communicates with the open portion where the inner opening 23 a that opens into the thermal spray booth 19 opens to the crankcase side below the cylinder block 1 via the guide portion 29. The outer opening 23b of the lower exhaust pipe 23 opens to the outside of the thermal spray booth 19, and communicates with a suction device 31 including, for example, a fan.

  The air in the spraying booth 19 is also sucked from the side exhaust pipe 25 and the upper exhaust pipe 27 in addition to the lower exhaust pipe 23, but this suction force is weaker than the suction force from the lower exhaust pipe 23 and the suction amount is reduced. To do. In this case, a fan or the like is provided for each of the side exhaust pipe 25 and the upper exhaust pipe 27. Alternatively, air is sucked from the lower, side, and upper exhaust pipes 23, 25, and 27 by the same suction device, and a flow control valve is provided in each exhaust pipe 23, 25, and 27 or a passage connected to these exhaust pipes. The flow rate control valve may be controlled by a control unit (not shown).

  By sucking air in the thermal spray booth 19 from the lower exhaust pipe 23, the side exhaust pipe 25 and the upper exhaust pipe 27, external air flows into the thermal spray booth 19 through the intake pipe 21. The air that has flowed into the thermal spray booth 19 mainly passes through the cylinder bore 3 and is discharged from the lower exhaust pipe 23 to the outside of the thermal spray booth 19. A part of the air flowing into the thermal spray booth 19 from the intake pipe 21 is discharged from the side exhaust pipe 25 and the upper exhaust pipe 27 to the outside of the thermal spray booth 19.

  In the cylinder bore 3, as shown in FIG. 4, air flows along the axial direction of the four cylinder bores 3 as indicated by an arrow C from the opening on the cylinder head mounting surface side toward the lower portion. The air flowing through the four cylinder bores 3 merges in the guide portion 29 on the lower outlet side. Further, by sucking air also from the side exhaust pipe 25 and the upper exhaust pipe 27, an air flow is generated around the cylinder block 1 as indicated by arrows D and E.

  In a state where such an air flow is generated in the spraying booth 19, the spray coating 17 is formed in order from the one side in the arrangement direction to the other side of the four cylinder bores 3 by the spray gun 5. Perform the work. FIG. 4 shows a state in which a thermal spray coating 17 is formed on the first cylinder bore 3 at the left end in the drawing, and then the second, third, and fourth on the right side adjacent thereto. The thermal spray coating 17 is sequentially formed on the cylinder bores 3.

  Here, in order to increase the adhesion of the thermal spray coating 17 to the inner surface of the cylinder bore 3 that is the sprayed surface, the cylinder block 1 may be preheated. FIG. 5 shows the temperature change of the cylinder block 1 when the sprayed coating is formed in the spraying booth 19 shown in FIG. 1 after the cylinder block 1 is heated to, for example, about 170 ° C. in a preheating furnace or the like. ing. The solid line is the temperature of the first cylinder bore 3A, and the broken line is the temperature of the fourth cylinder bore 3D.

  In FIG. 5, suction is started with respect to the air in the thermal spray booth 19 at time t1. At this time, air is sucked from the lower exhaust pipe 23, the side exhaust pipe 25, and the upper exhaust pipe 27 and discharged to the outside, and the external air is supplied into the thermal spray booth 19 through the intake pipe 21. By sucking the air in the thermal spray booth 19, an air flow, that is, an air flow is generated in the thermal spray booth 19, and the cylinder block 1 (first to fourth cylinder bores 3) is cooled by the influence of the air flow. The temperature drops.

  When thermal spraying is started on the first cylinder bore 3A at time t2, the temperature of the first cylinder bore 3A rises due to thermal spraying. While thermal spraying is being performed on the first cylinder bore 3A, the temperature of the fourth cylinder bore 3D gradually decreases due to the continuously generated airflow. When thermal spraying is started on the fourth cylinder bore 3D at time t3, the temperature of the fourth cylinder bore D3 rises due to thermal spraying.

  When the second and third cylinder bores 3B and 3C are sprayed, the temperature gradually decreases due to the continuously generated air flow as in the case of the fourth cylinder bore 3D, and the subsequent spraying starts. Sometimes the temperature rises due to thermal spraying.

  Thus, the temperature of the cylinder bore 3 gradually decreases with respect to the temperature immediately after the preheating, and the adhesion of the thermal spray coating 17 decreases due to the temperature decrease. Therefore, in the present embodiment, the cylinder bore 3 is heated in order to suppress a decrease in the adhesion of the thermal spray coating 17 due to a temperature decrease.

  FIG. 6 shows a method for heating the periphery of the cylinder bore 3 according to the first embodiment. The heating method according to the first embodiment uses a heater 33 as a heater serving as a heat source. The heater 33 includes a base portion 33 a and a substantially U-shaped heat generating portion 33 b extending downward from the base portion 33 a, and the heat generating portion 33 b is inserted into the cylinder bore 3. The base portion 33a includes an electric circuit for causing the heat generating portion 33b to generate heat. The length from the base 33a to the tip (the lower end in FIG. 6) of the heat generating portion 33b is substantially equal to the length of the cylinder bore 3 in the axial direction.

  In FIG. 6, the first cylinder bore 3A is sprayed and a spray coating 17 is formed, and the spray gun 5 is inserted into the second cylinder bore 3B for spraying. And the heat generating part 33b of the heater 33 is inserted into the third cylinder bore 3C and the fourth cylinder bore 3D, respectively, to heat the periphery of the cylinder bores 3C and 3D. That is, when the cylinder bore 3 is heated, at least the periphery of the cylinder bore 3C to be sprayed next is heated with respect to the cylinder bore 3B that is currently sprayed.

  Here, when the spraying of the cylinder bore 3B is completed, the heater 33 is taken out from the cylinder bore 3C, and then the spray gun 5 is inserted into the cylinder bore 3C to perform the spraying. At this time, the cylinder bore 3D is continuously heated. Since the cylinder bore 3C is heated by the heater 33 before spraying, even if air flows in the cylinder bore 3C due to dust collection, temperature drop due to the dust collection air is suppressed. For this reason, the adhesion of the thermal spray coating 17 formed on the cylinder bore 3C is high, and the thermal spray coating 17 with high reliability is obtained.

  Similarly, when the spraying of the cylinder bore 3C is completed, the heater 33 is taken out from the cylinder bore 3D, and then the spray gun 5 is inserted into the cylinder bore 3D for spraying. Since the cylinder bore 3D is heated by the heater 33 before spraying, even if air is flowing in the cylinder bore due to dust collection, the temperature drop due to the dust collection air is suppressed, and therefore the thermal spray formed on the cylinder bore 3D. The adhesion of the film 17 is high.

  The second cylinder bore 3B is also heated by the heater 33 when the first cylinder bore 3A is sprayed, so that the temperature drop due to the dust collection air is suppressed. Will be expensive. The first cylinder bore 3A is sprayed first after the cylinder block 1 is preheated, so the temperature drop due to the dust collection air is small, and thus the temperature is kept high. The adhesion strength of 17 is high.

  Thus, in the first embodiment, at least the periphery of the cylinder bore 3 to be sprayed next is heated with respect to the cylinder bore 3 that is currently spraying. Thereby, since the temperature fall of the cylinder bore 3 by dust collection air is suppressed, the contact | adhesion power of the thermal spray coating 17 can be maintained highly, and the thermal spray coating 17 with high reliability can be obtained.

  In the first embodiment, the periphery of the cylinder bore 3 is heated by the heater 33 that is a heater provided inside the cylinder bore 3. For this reason, the cylinder bore 3 can be heated more reliably with a simple configuration. In FIG. 6, when the cylinder bore 3B is sprayed, the two cylinder bores 3C and 3D are heated. However, only the cylinder bore 3C to be sprayed next may be heated. In this case, since only one heater 33 is required, cost reduction such as equipment costs can be realized.

  FIG. 7 shows a method of heating the periphery of the cylinder bore 3 according to the second embodiment. In the heating method according to the second embodiment, hot air 35 serving as a heat source is supplied to the cylinder bore 3. The hot air 35 is supplied from a hot air supply unit 37 that includes, for example, a heater and a blower such as a blower that sends air heated by the heater to the cylinder bore 3. In order to supply warm air to the individual cylinder bores 3 by the blower, a duct may be connected to the blower. By connecting the end of the duct opposite to the blower so as to cover the opening of each cylinder bore 3, the hot air can be reliably supplied to the individual cylinder bores 3.

  In FIG. 7, as in FIG. 6, the first cylinder bore 3A has been sprayed and the spray coating 17 is formed, and the spray gun 5 is inserted into the second cylinder bore 3B for spraying. Then, warm air 35 is supplied to the third cylinder bore 3C and the fourth cylinder bore 3D instead of heating by the heater 33 to heat the periphery of the cylinder bores 3C and 3D. That is, when the cylinder bore 3 is heated, at least the periphery of the cylinder bore 3C to be sprayed next is heated with respect to the cylinder bore 3B that is currently sprayed.

  Here, when the spraying of the cylinder bore 3B is completed, the supply of the hot air 35 to the cylinder bore 3C is stopped, and then the spray gun 5 is inserted into the cylinder bore 3C to perform the spraying. At this time, the hot air 35 is continuously supplied to the cylinder bore 3D. Since the cylinder bore 3C is heated by the warm air 35 before spraying, even if air flows in the cylinder bore 3C due to dust collection, temperature drop due to the dust collection air is suppressed. For this reason, the adhesion of the thermal spray coating 17 formed on the cylinder bore 3C is high, and the thermal spray coating 17 with high reliability is obtained.

  Similarly, when the spraying of the cylinder bore 3C is completed, the supply of the warm air 35 to the cylinder bore 3D is stopped, and then the spray gun 5 is inserted into the cylinder bore 3D to perform the spraying. Since the cylinder bore 3D is heated by the hot air 35 before spraying, even if air is flowing in the cylinder bore 3D due to dust collection, the temperature drop due to the dust collection air is suppressed, and therefore the cylinder bore 3D is formed in the cylinder bore 3D. The adhesion of the sprayed coating 17 is high.

  The second cylinder bore 3B is also heated by the warm air 35 when the first cylinder bore 3A is sprayed, so that the temperature drop due to the dust collection air is suppressed. Power is high. The first cylinder bore 3A is sprayed first after the cylinder block 1 is preheated, so the temperature drop due to the dust collection air is small, and thus the temperature is kept high. The adhesion strength of 17 is high.

  Accordingly, also in the second embodiment, at least the periphery of the cylinder bore 3 to be sprayed next is heated with respect to the cylinder bore 3 that is currently spraying. Thereby, since the temperature fall of the cylinder bore 3 by dust collection air is suppressed, the contact | adhesion power of the thermal spray coating 17 can be maintained highly, and the thermal spray coating 17 with high reliability can be obtained.

  In the second embodiment, warm air is supplied into the cylinder bore 3 to heat the periphery of the cylinder bore 3. For this reason, the inner surface of the cylinder bore 3 can be heated more uniformly. Also in the second embodiment, when the cylinder bore 3B is sprayed, the two cylinder bores 3C and 3D are heated by the hot air 35, but the hot air 35 is applied only to the cylinder bore 3C to be sprayed next. You may make it supply and heat.

  FIG. 8 shows a method of heating the periphery of the cylinder bore 3 according to the third embodiment. In the heating method according to the third embodiment, the inside of the water jacket 39 of the cylinder block 1 is heated by a heater 41 as a heater. The heater 41 includes a base portion 41a and a substantially U-shaped heat generating portion 41b extending downward from the base portion 41a, as in the heater 33 of FIG. 6, and the heat generating portion 41b as shown in FIG. Insert inside. The base 41a includes an electric circuit for causing the heat generating part 41b to generate heat. The length from the base 41a to the tip (the lower end in FIG. 8A) of the heat generating portion 41b is substantially equal to the depth of the water jacket 39.

  Then, while the inside of the water jacket 39 is heated by the heater 41, a sprayed coating is sequentially formed on the inner surface of the cylinder bore 3 (3 </ b> A, 3 </ b> B, 3 </ b> C, 3 </ b> D) by the spray gun 5. In FIG. 8, the heaters 41 are disposed on the water jackets 39 at positions corresponding to the four cylinder bores 3 </ b> A, 3 </ b> B, 3 </ b> C, 3 </ b> D on both sides of the cylinder bore 3. That is, eight heaters 41 are used in total.

  In this case, all eight heaters 41 are operated and heated while spraying the four cylinder bores 3A, 3B, 3C, 3D. Alternatively, as in the first and second embodiments, the cylinder bore 3 that is currently sprayed is provided in the vicinity of the cylinder bore 3 to be sprayed next so that at least the periphery of the cylinder bore 3 to be sprayed next is heated. Only a certain heater 41 may be operated.

  As described above, also in the third embodiment, at least the periphery of the cylinder bore 3 to be sprayed next is heated with respect to the cylinder bore 3 that is currently spraying. Thereby, since the temperature fall of the cylinder bore 3 by dust collection air is suppressed, the contact | adhesion power of the thermal spray coating 17 can be maintained highly, and the thermal spray coating 17 with high reliability can be obtained.

  Further, in the third embodiment, the periphery of the cylinder bore 3 is heated by the heater 41 which is a heater provided inside the water jacket 39 of the cylinder block 1. For this reason, heating around the cylinder bore 3 can be more reliably performed with a simple configuration.

  FIG. 9 shows a method of heating the periphery of the cylinder bore 3 according to the fourth embodiment. In the heating method according to the fourth embodiment, hot air 43 is supplied into the water jacket 39 of the cylinder block 1. Here, when supplying warm air, the masking member 45 is disposed in a sealed state on the cylinder head mounting surface 1 a of the cylinder block 1. A cylinder head (not shown) is attached to the cylinder head attachment surface 1a.

  The masking member 45 is a rectangular plate-like member corresponding to the longitudinal direction of the cylinder block 1, and includes a circular opening 45 a corresponding to the end opening of the cylinder bore 3, and the water jacket 39 and the outer cavity 47. Is blocking. The masking member 45 includes an inlet duct 49 for supplying hot air on one end side in the arrangement direction of the four openings 45a, and an outlet duct 51 for discharging hot air on the other end side.

  The inlet duct 49 described above rises upward from the flat plate portion 45b of the masking member 45 and curves outward, and includes a hot air supply port 49a at the tip thereof. The lower opening of the inlet duct 49 opposite to the hot air supply port 49a communicates with the water jacket 39 in a state where the masking member 45 is disposed in a sealed state on the cylinder head mounting surface 1a as shown in FIG. 9B.

  Similarly, the outlet duct 51 rises upward from the flat plate portion 45b of the masking member 45, curves outward, and includes a hot air discharge port 51a at the tip thereof. The lower opening of the outlet duct 51 opposite to the hot air outlet 51a communicates with the water jacket 39 in a state where the masking member 45 is disposed on the cylinder head mounting surface 1a in a sealed state as shown in FIG. 9B.

  When performing the thermal spraying operation, the masking member 45 shown in FIG. 9A is placed on the cylinder head mounting surface 1a of the cylinder block 1 as shown in FIG. 9B, and a separate fixture or the like is used. And fix it. At this time, in the masking member 45, the opening 45 a is aligned with the end opening of the cylinder bore 3 and closes the end opening of the water jacket 39 and the end opening of the cavity 47.

  In this state, when the hot air 43 is supplied from the hot air supply port 49 a as shown in FIG. 9C, the supplied hot air 43 flows into the water jacket 39 through the inlet duct 49. The water jacket 39 is formed so as to surround the periphery of the four cylinder bores 3, and a bottom wall forming a bottom portion is formed on the lower crankcase side in FIG. 9 opposite to the cylinder head mounting surface 1 a. Yes.

  Accordingly, the hot air 43 flowing into the water jacket 39 flows along the circumferences of the four cylinder bores 3 and heats the outer walls around the four cylinder bores 3. The heated hot air 43 is exhausted from the hot air outlet 51 a of the outlet duct 51 as exhaust 55. In this way, while the periphery of the four cylinder bores 3 is heated, the sprayed gun 5 sequentially forms a sprayed coating on the inner surface of the cylinder bores 3 (3A, 3B, 3C, 3D).

  As mentioned above, also in 4th Embodiment, the inside of the water jacket 39 which is the circumference | surroundings of the cylinder bore 3 sprayed at least next is heated with respect to the cylinder bore 3 currently spraying. Thereby, since the temperature fall of the cylinder bore 3 by dust collection air is suppressed, the contact | adhesion power of the thermal spray coating 17 can be maintained highly, and the thermal spray coating 17 with high reliability can be obtained. Moreover, since warm air is supplied to the inside of the water jacket 39 and the periphery of the cylinder bore 3 is heated from the outside, the inner surface of the cylinder bore 3 can be heated more uniformly.

  In the fourth embodiment, the warm air 43 is supplied to the water jacket 39 with the masking member 45 disposed on the cylinder head mounting surface 1a. For this reason, the warm air 43 can be supplied to the water jacket 39 more reliably, and the surroundings of the cylinder bore 3 can be heated more reliably.

  In each of the above-described embodiments, the workpiece is the engine cylinder block 1 and the hole is the cylinder bore 3. For this reason, when the spray coating 17 is formed on the inner surface of the cylinder bore 3, even if the cylinder block 1 is preheated in advance and dust collection gas is allowed to flow through the cylinder bore 3 during spraying, Heating with a heater or warm air can suppress a decrease in temperature, and a decrease in adhesion of the thermal spray coating 17 can be suppressed.

  As mentioned above, although embodiment of this invention was described, these embodiment is only the illustration described in order to make an understanding of this invention easy, and this invention is not limited to the said embodiment. The technical scope of the present invention is not limited to the specific technical matters disclosed in the above embodiment, but includes various modifications, changes, alternative techniques, and the like that can be easily derived therefrom. For example, in the above-described embodiment, the cylinder block 1 of the in-line four-cylinder engine has been described. However, the present invention can also be applied to a cylinder block of an in-line six-cylinder engine or a V-type six-cylinder engine.

  In addition, although the heaters 41 in FIG. 8 are arranged corresponding to the four cylinder bores 3, only the periphery of the cylinder bore 3 to be sprayed next is heated with respect to the cylinder bore 3 to be sprayed. The heater 41 may be only two. In this case, as the thermal spraying is sequentially performed on the four cylinder bores 3, the two heaters 41 are also moved sequentially. Although the eight heaters 41 in FIG. 8 are separate bodies, they may be integrated. Thereby, the insertion operation | work to the water jacket 39 of a heater becomes easy.

1 Cylinder block (work)
1a Cylinder head mounting surface of cylinder block 3 Cylinder bore (hole)
5 Thermal spray gun 17 Thermal spray coating 33, 41 Heater (heater, heat source)
35, 43 Hot air (heat source)
39 Water jacket 45 Masking member 45a Masking member opening 49a Hot air supply port 51a Hot air discharge port

Claims (7)

A thermal spraying method for continuously forming a thermal spray coating on the inner surface of a plurality of holes formed in a workpiece,
The thermal spraying method characterized by heating the inner surface of the hole sprayed at least next to the hole sprayed by the thermal spray gun among the plurality of holes by a heat source different from the thermal spray gun.   The heat source is a heater different from the spray gun, and the heater provided at least inside the hole sprayed at least next to the hole sprayed by the spray gun among the plurality of holes, 2. The thermal spraying method according to claim 1, wherein an inner surface of a hole to be sprayed at least next to a hole sprayed by the thermal spray gun among a plurality of holes is heated.   The heat source is hot air supplied from a hot air supply unit different from the spray gun, and the inside of the hole sprayed at least next to the hole sprayed by the spray gun among the plurality of holes. 2. The inner surface of the hole to be sprayed at least next to the hole sprayed by the spray gun among the plurality of holes is heated by supplying the hot air to Thermal spraying method.   The workpiece is a cylinder block of an engine, the hole is a cylinder bore, the heat source is a heater different from the spray gun, and the cylinder bore is formed by the heater provided inside a water jacket of the cylinder block. The thermal spraying method according to claim 1, wherein the inner surface of the substrate is heated.   The workpiece is a cylinder block of an engine, the hole is a cylinder bore, the heat source is hot air supplied from a hot air supply unit different from the spray gun, and the water block is provided inside the water jacket of the cylinder block. The thermal spraying method according to claim 1, wherein the warm air is supplied to heat an inner surface of the cylinder bore.   A hot air supply port provided in the masking member, wherein a masking member that closes an end opening of the water jacket and has an opening corresponding to the end opening of the cylinder bore is disposed on the cylinder head mounting surface of the cylinder block. The warm air supplied from the inside is flown into the water jacket to heat the inner surface of the cylinder bore, and the heated warm air is discharged from the warm air outlet provided in the masking member to the outside of the water jacket. The thermal spraying method according to claim 5, wherein   The thermal spraying method according to claim 1, wherein the workpiece is a cylinder block of an engine, and the hole is a cylinder bore.

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