JP2002285313A - Cylinder block thermal spraying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder block thermal spraying method causing high productivity and excellent quality by performing thermal spraying on a bore surface of a plurality of cylinder blocks of the type having no crank case. SOLUTION: The cylinder block thermal spraying method for performing thermal spraying on the bore surface 1 of the cylinder block 3 comprises a step for providing a space between bore ends of the cylinder block 1, and a step for spraying thermal spraying flame 33 on the bore surface 1 in a space- provided state. As the method for providing the space between the bore ends, a method for chamfering one side of an end in the axial direction of the bore 5 around the circumferential direction and a method for disposing cylinder blocks 3 separate from each other in the axial direction are exemplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal spraying method for simultaneously and efficiently treating a plurality of cylinder blocks when forming a thermal spray coating on a bore surface of a cylinder block having no crankcase.

[0002]

2. Description of the Related Art Normally, in a cylinder block of an internal combustion engine made of an aluminum alloy, a method of forming a film having excellent wear resistance and seizure resistance on the surface of the cylinder block is adopted in order to improve the durability of the bore surface. Thermal spraying is one of the methods. Here, thermal spraying means supplying powder or wire made of metal or metal oxide into a heat source, heating and melting instantaneously, and colliding and welding the droplets at high speed to the workpiece. This is a method of forming a film on the surface of the agent to be treated. This spraying
Since there is a high degree of freedom in selecting the material of the coating and the material to be treated, it has been put to practical use as the surface treatment of the bore surface of the cylinder block described above, and many proposals have been made. Conventional techniques using this thermal spraying include, for example, Japanese Patent Publication No. 59-618.
Japanese Patent Application Laid-Open No. 8 (1999) -1995 proposes a method in which a cylinder block is fixed on a table, rotated while being clamped, and the spray gun is moved up and down to spray the bore surface.

[0003]

However, in the above-mentioned conventional technique, thermal spraying is performed one cylinder block at a time, and therefore, it is necessary to repeat clamping and unclamping every time one cylinder block is processed. Occurred many times. For this reason, the problem is remarkable in a single cylinder cylinder block with low production efficiency, particularly with a small number of cylinders. Therefore, it is desired to spray a plurality of cylinder blocks at one time, but there has been no such technique in the past.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and in particular, in a cylinder block without a crankcase, a plurality of cylinder blocks having high productivity and excellent quality are formed by simultaneously spraying a plurality of bore surfaces thereof. It is intended to provide a thermal spraying method.

[0005]

In order to achieve the above object, a method for spraying a cylinder block according to the present invention comprises the steps of: Providing a gap in the bore matching part and stacking in the axial direction;
In this state, a step of spraying the thermal spray frame to the bore surface is included. According to this thermal spraying method, thermal spraying can be simultaneously performed on a plurality of cylinder blocks, so that the productivity of the cylinder blocks can be greatly improved. Further, the thermal spray frame is sprayed obliquely upward or at right angles to the bore surface, but the thermal spray frame is blocked by the lower end of the bore of the upper cylinder block that is not chamfered. Therefore, since the thermal spraying is not performed on the bore ends of the upper and lower cylinder blocks, there is no problem that the thermal spray coating is peeled off when the cylinder block is removed.

Further, in one aspect of the method for spraying a cylinder block according to the present invention, the step of providing a gap in the bore mating portion includes chamfering a bore surface at one axial end of the bore along a circumferential direction. In this method, a plurality of cylinder blocks are stacked so that one end thereof is on the upper side, and thereby a recess is formed in a bore matching portion between upper and lower cylinder blocks. When one end of the bore of the cylinder block is chamfered and the cylinder blocks are stacked with the chamfered side facing upward, concave portions are formed on the bore mating surfaces of the upper and lower cylinder blocks. In this state, if the thermal spray coating is formed on the bore surface, the thermal spray coating is divided between the stacked cylinder blocks, and the thermal spray coating does not peel off when the cylinder block is removed after the thermal spraying. Therefore, a plurality of spray cylinders having excellent quality can be manufactured at the same time. Further, since the upper and lower cylinder blocks are in close contact with each other, no thermal spray coating is formed on the surfaces other than the bore surfaces of each other, so that masking between the cylinder blocks is unnecessary.
The shape of the concave portion is not particularly limited, and various shapes such as a substantially triangular cross section and a substantially fan-shaped cross section can be adopted.

In another aspect of the cylinder block thermal spraying method according to the present invention, the concave portion has a thickness of the thermal sprayed coating of t, a depth of the concave portion in a bore radial direction of L1, and a height of the concave portion of L2. In this case, L1 ≧ 2t and L2 ≧ 2t. If the hole has a diameter almost twice as large as that of the thermal spray coating, the sealing treatment can be performed. If L1 which is the depth of the recess in the bore diameter direction and L2 which is the height of the recess is not less than twice the thickness of the sprayed coating, the sprayed coating will not be integrated and continuous. In addition, when the cylinder block is removed, the sprayed coating does not peel off.

In another aspect of the cylinder block spraying method according to the present invention, the step of providing a gap in the bore matching portion includes disposing the cylinder blocks at an interval above and below the cylinder block. Is a method of forming such that D ≧ 2t, where t is the thickness of the thermal spray coating. According to the thermal spraying method, the bore surface is discontinuous by providing a gap between the cylinder blocks and stacking the cylinder blocks. Therefore, when the thermal spray coating is formed, the thermal spray coating is divided between the stacked cylinder blocks, and the thermal spray coating does not peel off when the cylinder block is removed after the thermal spraying is completed. Therefore, a cylinder block having excellent quality can be manufactured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for spraying a cylinder block according to an embodiment of the present invention will be described below in detail with reference to the drawings.

The method of spraying a cylinder block according to an embodiment of the present invention is a method of stacking a plurality of cylinder blocks in a vertical direction such that the center axes of the cylinders substantially coincide with each other, particularly in a cylinder block having no crankcase. This is a method of spraying the bore surface with the bore set so that it looks like a single cylinder. In this case, by preventing the thermal spray coating from being continuously formed between the stacked cylinder blocks, it is possible to prevent the thermal spray coating from being peeled when the cylinder block is removed after the thermal spraying is completed.

FIG. 1A is a sectional view showing an example of the cylinder block 3 before thermal spraying is performed on the bore surface 1. A bore 5 penetrates the cylinder block 3 in the axial direction, and a bore surface 1 which is an inner peripheral surface of the bore 5 is a sliding surface of a piston. The upper surface of the cylinder block 3 is formed on the cylinder head surface 15, and the lower portion is formed on the skirt 17. This cylinder block 3
Is a type in which a crankcase is not provided below the skirt portion 17. Further, as shown in FIG. 1 (b), the lower end of the bore surface of the skirt portion 17 of the cylinder block 3 is formed in a cutout surface 7 which is chamfered along the circumferential direction, and is indicated by a dashed line. As compared with the shape 9 before the chamfering, the lower end of the bore surface 1 is formed so as to extend obliquely downward toward the outer peripheral direction by the cutout surface 7.

[First Embodiment] In a first embodiment, a cylinder block 3 in which an end of a bore surface 1 is chamfered is stacked one on another, and the cutout surface 7 is provided between the cylinder blocks 3 and 3. Is a method in which thermal spraying is performed on the bore surface 1 in a state where the concave portion is formed.

First, as shown in FIG. 1B, the cylinder block 3 in which the lower end of the bore surface is chamfered is turned upside down, and the skirt portion in which the notch 11 is formed by the notch 7 is turned upward. With the cylinder head surface 15 facing down, as shown in FIG.
Are stacked. At this time, in order to prevent the upper and lower bore surfaces 1 and 1 from shifting in the radial direction, the fixing jigs 2 are fixed so that the bore central axes of the respective cylinder blocks 3 and 3 coincide.
Position and fix with 1.

Cylinder head surface 1 of cylinder block 3
5 and fins 6 are provided with positioning recesses or holes 23 in advance.
(Refer to FIG. 1A). The positioning and fixing are performed by fitting the convex portion 25 of the fixing jig 21 into these concave portions or holes 23. In this state, as shown in FIG. 3, the surface 13 on the skirt portion side of the lower cylinder block 3 and the cylinder head surface 15 of the upper cylinder block 3 are in contact with each other. A recess 27 having a substantially right-angled triangular cross section is formed at the side end (bore matching portion) by the cylinder head surface 15 and the cutout surface 7.

Next, while rotating the cylinder block 3 which is the object to be processed, the thermal spray gun 29 is inserted into the bore 5 and moved up and down to form the thermal spray coating 31 on the entire bore surface 1. it can. At this time, FIG.
As shown in the figure, in the concave portion 27 formed in the bore mating portion,
A portion that becomes a shadow with respect to the thermal spray frame 33 ejected from the thermal spray gun 29 is generated. When spraying the thermal spray frame 33 from the thermal spray gun 29 to perform thermal spraying, the thermal spraying is performed from an obliquely upper side with a spray angle θ to the bore surface 1 arranged in a substantially vertical direction. Is generally in the range of 30 to 90 °, and the spraying flame is prevented by the corner 1a of the bore surface 1 between the cylinder head surface 15 forming the recess 27 and a part of the cutout surface 7. 33 is not injected. In addition, when jetting from a direction perpendicular to the bore surface 1 (θ = 90 °)
Is sprayed in the horizontal direction with respect to the cylinder head surface 15, so that the thermal spray coating 31 is not formed.

Therefore, the thermal spray coating 3 formed on the bore surface 1
1 is cut off at the shadowed portion between the upper and lower cylinder blocks 3, 3, and does not peel off the thermal spray coating 31 when the cylinder block 3 after the thermal spraying is removed from the fixing jig 21. As described above, since the thermal spraying is performed on the cylinder blocks 3 and 3 while the cylinder head surface 15 and the surface 13 on the skirt portion are in close contact with each other, unnecessary portions other than the mutual bore surfaces 1 and 1 are formed. The effect of preventing the thermal spray coating 31 from being formed is also obtained, and the cylinder blocks 3, 3
Intermediate masking is not required.

As shown in FIG. 3, a desirable dimension range of the chamfered concave portion 27 is as follows.
Assuming that the depth of the recess is L1 and the height of the recess is L2, L1 ≧ 2
t and L2 ≧ 2t. Here, thermal spraying is a surface treatment method in which a molten material is sprayed onto a material to be treated at a high speed and welded to form a film on the surface of the material to be treated, so that small holes and the like can be sealed. Have been. The present inventors have conducted intensive studies and as a result, it has been found that if the diameter of the hole is approximately twice (2t) the thickness t of the thermal sprayed coating 31, it is possible to perform the sealing treatment by spraying. And the dimensions of the recess 27 are found. Therefore, in order to separate the thermal spray coating 31 between the cylinder blocks 3 and 3 without the concave portions 27 between the stacked cylinder blocks 3 and 3 being sealed by thermal spraying, L1 ≧ 2t under the above conditions, and L2 ≧ 2t is required, and the larger the chamfer dimension, the greater the effect of dividing the thermal spray coating 31. Here, the upper limits of L1 and L2 should be designed values in consideration of the product characteristics, and are, for example, 5 mm.

In some cases, a normal chamfer 55 is formed at the bore end of the cylinder block 3 for the purpose of deburring or the like. However, the chamfer referred to in the present invention is different from this, and as shown in FIG. 4, when a chamfer 55 for deburring or the like is provided, the chamfer 55 further reduces the L1 and L2. The notch surface 7 is formed by chamfering the dimensional conditions. On the other hand, FIG.
As shown in (a), when the bore surfaces 1, 1 of the upper and lower cylinder blocks 3, 3 are set to be continuous, the bore surface 1
Spray coating 31 formed on the upper and lower cylinder blocks 3
, Resulting in a continuous integrated thermal spray coating 31. As a result, as shown in FIG. 5 (b), if the cylinder block 3 is removed after the end of the thermal spraying, the thermal spray coating 31 will peel off.

Further, as shown in FIG.
When the cylinder blocks 3 are stacked with the skirt portion side surface 13 provided with the upper side facing upward and the cylinder head surface 15 without the notch surface 7 facing downward, the formed concave portion 27 is shadowed with respect to the thermal spray frame. Therefore, if thermal spraying is performed in this state, the thermal spray coating 31 will be continuous and integral with the upper and lower cylinder blocks 3. As a result, when the cylinder block 3 is removed, as shown in FIG. 6B, the thermal spray coating 31 is peeled off, and the cylinder head surface 15 of the lower cylinder block 3 which is not chamfered is further removed.
In this case, there is a problem that the coating 31 is formed on an unnecessary portion 35 of the thermal spray coating 31.

[Second Embodiment] In a second embodiment, in FIG. 7, as an example, a bore end of a cylinder head surface 15 is chamfered, and the cylinder head surfaces 15, 15 are connected to each other. The recess 41 having a substantially isosceles triangular cross section is formed by abutting and aligning the notches of the cylinder blocks 3 and 3. Also in this case, the first
As described in the embodiment, since the thermal spray frame 33 is sprayed onto the bore surface 1 obliquely from above at the spray angle θ, the concave portion 41 that satisfies the following dimensional conditions becomes a shadow with respect to the thermal spray frame 33. A part is generated, and the thermal spray coating 31
When the cylinder block 3 is removed after the end of the thermal spraying, the thermal spray coating 31 does not peel off. Further, an effect of preventing the thermal spray coating 31 from being formed on unnecessary portions can be obtained.

As shown in FIG. 8, the dimensional condition of the concave portion 41 is such that the spray angle of the thermal spray frame 33 with respect to the moving direction of the thermal spray gun 29 is θ, and the cutout surface 7 of the upper cylinder block 3 and the bore surface 1 are different from each other. When the angle formed is α, the depth of the concave portion 41 is L1, and the height of the concave portion 41 is L2, θ ≦ α <90
°, L1 ≧ 2t, and L2 ≧ 2t. The upper limit value of L1 and L2 is 5 mm as in the case of the first embodiment.

Here, the angle range of θ ≦ α <90 ° is a range in which a part of the concave portion 41 becomes a shadow with respect to the thermal spray frame 33 and the thermal spray coating 31 is hardly formed in the concave portion 41. In particular, when α = 90 °, the state is the same as that of the first embodiment, and when α> 90 °, the shape cannot be said to be a chamfered shape, so that θ ≦ α <90 °. Further, as shown in FIG. 7 and FIG. 8, the notched portions of the upper and lower cylinder blocks 1, 1 which are stacked need not be the same, and as shown in FIG. Even if the shapes are different like the notched surfaces 7 and 7 ', there is no problem as long as θ, L1, and L2 satisfy the above conditions. As mentioned above,
The chamfering is performed at one end of the bore ends of the cylinder blocks 3 and 3 as in the first embodiment, and the stacking is performed such that the chamfered end is on the upper side or the second embodiment. As in the form, one end of the bore end is chamfered,
The chamfered ends may be stacked so as to match, or both ends may be chamfered.

[Third Embodiment] A third embodiment is a method of forming a gap between stacked cylinder blocks without chamfering the end of the bore surface. That is, as shown in FIG. 10 and FIG. 11, the cylinder blocks 3 and 3 are positioned and fixed by the fixing jig as in the first embodiment, but the height of the fixing jig 43 is When the bore surface 1 is subjected to thermal spraying by providing a gap D between the upper and lower cylinder blocks 3, 3, the thermal spray coating 31 is divided at the gap D. Thermal spray coating 3 when removing block 3
No 1 is peeled off. The range of the gap D needs to be D ≧ 2t, where t is the thickness of the thermal spray coating 31 and D is the gap.

As described above, this is desirable as a condition for dividing the thermal spray coating 31 between the cylinder blocks 3 and 3 without forming the gap D when the thermal spray coating 31 is formed. However, if D is increased, the coating 31 is also formed on unnecessary portions of the thermal spray coating 31 other than the bore surface 1, and a step of removing the unnecessary coating 31 after thermal spraying may be required. It is desirable that the value of D be as small as possible within the range that satisfies. Based on this, a preferable upper limit value of D is, for example, 1 mm or less.

Hereinafter, the present invention will be described more specifically with reference to examples. [Example 1] Chamfering was performed on the bore end on the skirt side of a cylinder block without a crankcase under the dimensional conditions shown in Table 1. Then, three cylinder blocks each of which were chamfered under the same dimensional conditions were prepared, and the cylinder blocks were stacked with the chamfered side (skirt portion side) facing upward, and the plasma spraying method was applied to the bore surface under the spraying conditions shown in Table 2. To form a thermal spray coating. The angle θ of the flame sprayed from the spray gun is
The angle was set to 45 ° with respect to the moving direction of the spray gun, and the spray material was carbon steel powder. When the cylinder block was removed after the thermal spraying was completed, the number of defectives was examined, with the thermal spray coating peeled off or chipped at one of the upper and lower ends of the bore. Table 1 shows the results.

[0026]

[Table 1]

[0027]

[Table 2]

As can be seen from Table 1, when both L1 and L2 exceed 500 μm = 0.5 mm, which is twice the thickness of the thermal spray coating, a thermal spray coating of stable quality is formed without occurrence of defects. I was able to.

[Embodiment 2] Three cylinder blocks without a crankcase are prepared, and a gap D between the cylinder blocks is prepared.
Was set to 1 mm, and a thermal spray coating was formed on the bore surface. The spraying conditions, the angle of the spraying frame, and the spraying material were the same as in Example 1. As a result, although thermal spraying was performed n = 3 times (the number of cylinders: 9), no peeling or chipping of the thermal spray coating occurred when the cylinder block was removed.

The present invention is not limited to the above-described embodiment, but can be variously modified and modified based on the technical concept of the present invention. For example, as a method of providing a gap between the cylinder blocks 3 and 3, as described above, the fixing jig 2 is provided between the cylinder blocks 3 and 3.
1 and 43 are set, and the method is not limited to the method of adjusting the height of the fixing jigs 21 and 43, and the gap can be formed by other conventional means.

When the thermal spray coating 31 is formed, the cylinder block 3 to be processed is rotated and the thermal spray gun 2 is rotated.
Although the method of fixing 9 has been described as an embodiment, the spraying gun 29 may be rotated instead of the cylinder block 3. As for the thermal spraying method, plasma spraying, arc spraying, high-speed flame spraying and the like can be applied.
Furthermore, the number of cylinders in the cylinder block 3 is not particularly limited, and the number of stacked cylinders is not limited.

As shown in FIG. 12, a plurality of cylinder blocks 3 are set on a transport pallet,
In a system that sprays continuously while transporting on the above,
By arranging the stacked cylinder blocks 3 in the horizontal direction, thermal spraying can be performed more efficiently. This method is particularly effective when spraying onto the cylinder block 3 having a small number of cylinders such as a single cylinder. The technique of the present invention can also be applied to thermal spraying pretreatment such as shot blasting, and a greater effect can be obtained by performing a series of processing from the pretreatment step to the thermal spraying processing.

[0033]

According to the method of spraying a cylinder block according to the present invention, a plurality of cylinder blocks can be sprayed simultaneously on their bore surfaces, particularly in a cylinder block without a crankcase, so that productivity is high, and High quality cylinder blocks can be produced.

[Brief description of the drawings]

1A is a sectional view of a cylinder block used for thermal spraying of the present invention, and FIG. 1B is an enlarged sectional view of a main part of FIG.

FIG. 2 is a cross-sectional view showing a state where the thermal spraying according to the first embodiment is performed.

FIG. 3 is an enlarged sectional view of a main part of FIG. 2;

FIG. 4 is a cross-sectional view showing a shape of a notch portion applicable to the first embodiment.

FIG. 5A is a cross-sectional view of a case where the upper and lower cylinder blocks are subjected to thermal spraying without providing notches,
(B) is a sectional view of a state where the cylinder block of (a) is removed.

6 (a) is a cross-sectional view in which the positional relationship of the cylinder block in FIG. 2 is upside down and thermal spraying is performed; FIG.
FIG. 2 is a cross-sectional view of a state where a cylinder block of FIG.

FIG. 7 is a cross-sectional view showing a state in which thermal spraying according to the second embodiment is being performed.

FIG. 8 is an enlarged sectional view of a main part of FIG. 7;

FIG. 9 is a cross-sectional view showing a shape of a notch portion applicable to the second embodiment.

FIG. 10 is a cross-sectional view showing a state where thermal spraying according to a third embodiment is performed.

FIG. 11 is an enlarged sectional view of a main part of FIG. 10;

FIG. 12 is a side view showing a state in which a cylinder block is continuously sprayed while being conveyed on a line.

[Description of Signs] 1 Bore surface 3 Cylinder block 5 Bore 7 Notch surface 11 Notch portion 13 Surface on skirt portion 15 Cylinder head surface 21, 43 Fixing jig 23 Positioning concave portion 25 Convex portion 27, 41 concave portion 29 Thermal spray gun 31 thermal spray coating 33 thermal spray frame 51 transport pallet 53 lines

Continued on the front page F term (reference) 3G024 AA22 AA31 AA33 AA36 AA37 AA42 BA18 CA20 DA16 FA06 FA14 GA19 GA35 HA07 4K031 AA02 AB02 DA01 EA02 EA04 EA05 EA09

Claims (4)

[Claims] In a method for spraying a cylinder block, a plurality of cylinder blocks are stacked in an axial direction with a gap formed in a bore matching portion, and a plurality of cylinder blocks are stacked with respect to the bore surface in this state. And spraying a thermal spray frame. 2. The step of providing a gap in the bore mating portion includes chamfering a bore surface at one axial end of the bore along a circumferential direction, and forming a plurality of cylinder blocks such that the one end is on the upper side. 2. The method according to claim 1, wherein a concave portion is formed in a bore matching portion between the upper and lower cylinder blocks. 3. The concave portion satisfies L1 ≧ 2t and L2 ≧ 2t when the thickness of the thermal spray coating is t, the depth of the concave portion in the bore radial direction is L1, and the height of the concave portion is L2. The method for spraying a cylinder block according to claim 2, wherein the spraying is performed as follows. 4. The step of providing a gap in the bore matching portion includes arranging the cylinder blocks vertically with a gap therebetween, and when the gap D is the thickness of the thermal spray coating, t ≧ D ≧ 4. The method for spraying a cylinder block according to claim 1, characterized in that the cylinder block is formed so as to be 2t.