JPH03236460A - Method and device for directly thermal-spraying valve lifter - Google Patents

Abstract

PURPOSE:To form a uniform thermally sprayed layer without causing a decrease in the hardness of a value lifter by passing cooling water through a lower holder in the course of the thermal spraying of a wear-resistant material on the side surface of the lifter and air-cooling the lifter. CONSTITUTION:An inverted cup-shaped valve lifter 21 made of a light metal is clamped by an upper holder 2 and a lower holder 3 and slowly rotated around its axis. A wear-resistant material is thermally sprayed on the side wall 23 of the lifter from a thermal spray gun 4 to form a thermally sprayed layer 11. Cooling water is passed through the cooling water passage 10 of the lower holder 3 in the course of thermal spraying. An air pump is simultaneously operated to inject cooling air on the end wall 22 and side wall 23 of the lifter 21 from the injection port 6 of the holder 3, and the lifter 21 is cooled. Consequently, a uniform thermally sprayed layer is obtained without generating steam due to dew condensation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal spraying method and apparatus for forming a thermal spraying layer on the surface of a light alloy direct impact type valve lifter to improve wear resistance.

[Prior Art] As shown in FIG. 2, a direct-acting valve lifter (hereinafter referred to as a valve lifter) has an upper end wall 22 and a side wall 2 on the side.
3, it has an inverted cup shape, and recently, in order to reduce weight, it is being considered to form it from an aluminum alloy. However, since aluminum alloys generally have insufficient wear resistance, it is necessary to perform the following thermal spraying treatment, for example.

That is, the end wall 22 of the valve lifter 21 is sandwiched from above and below by the substantially cylindrical upper holder 2 and the substantially cylindrical lower holder 13, and the valve lifter 21 is rotated around its axis by a known rotary drive device (not shown). Rotate more gently. Then, while moving the thermal spray gun 4 disposed on the side of the valve lifter 21 up and down, a wear-resistant material is sprayed from the thermal spray gun 4 onto the outer peripheral surface of the side wall 23 of the valve lifter 21 to form a thermal spray layer 11 . Typical wear-resistant materials used for this thermal spray layer 11 include, for example, N1-CrB-3i alloy and cermet.

[Problems to be Solved by the Invention] The above wear-resistant material is heated at a considerably high temperature (for example, N1-Cr-
In the case of B-3i alloy, it is thermally sprayed at about 100°C). Since this thermal spraying is performed while rotating the valve lifter 21 around its axis as described above, the valve lifter 21 is cooled to some extent by natural heat radiation while rotating. In addition, the valve lifter 21 dissipates the heat from the upper holder 2 and the lower holder 1.
It is also cooled by conduction to 3.

However, the cooling effect due to the above-mentioned natural heat dissipation was not very high, and the heat conduction to the holders 2 and 13 was also insufficient because the cooling effect decreased due to the temperature rise of the holders 2 and 13 themselves. Therefore, it is necessary to use valve lifter 2.
1 was heated to a considerably high temperature, which caused a problem in that the hardness of the aluminum alloy from which it was formed decreased.

This problem becomes more noticeable with small valve lifters.

In addition, since the holder 2.13 thermally expands due to the temperature rise, delicate adjustment of the clearance may be required to properly hold the valve lifter 21, or if the thermal spraying process is repeated continuously, the holder 2. The .13 itself also suffered from thermal deterioration due to repeated heating, which sometimes caused operational problems.

Therefore, it is necessary to forcefully cool the valve lifter 21 and the holders 2, 13, or if cooling water is applied directly to the valve lifter 21 and the holders 2, 13, the cooling water becomes water vapor due to the heat during thermal spraying, and the water vapor A new problem arose in that a uniform sprayed layer 11 could not be formed due to the adverse effect on the thermal spraying.

Moreover, if the pressure of the cooling air is too low, the cooling effect will be insufficient if the pressure of the cooling air is too low, and even if the pressure is high, the holder 2. , 13 was insufficient.

The purpose of the present invention is to solve the above-mentioned problems and to provide a direct-impinging type valve lifter that can form a uniform thermal spray layer without causing a decrease in the hardness of the light alloy valve lifter, and that can perform smooth thermal spraying operations. An object of the present invention is to provide a thermal spraying method and apparatus.

[Means for Solving the Problems] In order to achieve the above object, the thermal spraying method for a direct impact type valve lifter according to claim 1 includes an upper holder and an end wall of an inverted cup-shaped valve lifter made of a light alloy. A wear-resistant material is thermally sprayed from the side of the valve softer onto the outer circumferential surface of the side wall of the valve lifter while being held between the lower holder and rotated around the axis to form a thermally sprayed layer, and at least during the thermal spraying, the The lower holder is water-cooled by passing cooling water through the lower holder, and the valve lifter is air-cooled by blowing cooling air from the lower holder to the valve lifter.

A thermal spraying treatment apparatus for a direct impact type valve lifter according to claim 2 includes an upper holder and a lower holder that sandwich the end walls of an inverted cup-shaped valve softer formed of a light alloy, and a shaft that supports the upper holder and the lower holder. In the thermal spray processing apparatus, the lower holder includes a rotary drive device that rotates the valve lifter, and a thermal spray gun that seals a wear-resistant material from the side of the valve lifter to the outer peripheral surface of the side wall of the valve lifter. A jet hole opening toward the lower holder, an air passage communicating with the jet hole and allowing cooling air to pass therethrough, and a cooling water flow path through which cooling water passes within the lower holder are provided.

In this specification, "light alloy" refers to an alloy whose specific gravity is lower than 5, which is close to the average specific gravity of Fe and Afl, such as AfJ-3l alloy, A,Q-Cu alloy, A,l!
-Cu-Mg alloy (duralumin, super duralumin)
, A, Q -Zn-Mg alloy, An -ZnM g-C
Various A1 alloys such as u alloy (ultra super duralumin), Mg-
1 alloy, Mg-Zn alloy, Mg-A, Q-Zn alloy, M
Various Mg alloys such as g-Zn-Zr alloy, Ti-A, 1l
Various Ti alloys such as -V alloy can be exemplified.

[Function] According to the thermal spray processing apparatus and its apparatus of the present invention, the valve lifter is effectively forcedly cooled during thermal spraying by the following function.

(2) By passing cooling water through the cooling water flow path of the lower holder to cool the lower holder, heat from the thermal spraying from the valve lifter is quickly conducted to the lower holder.

(2) The valve lifter directly radiates heat by cooling the valve lifter by jetting cooling air from the jet hole of the lower holder to the valve lifter. At this time, since the lower holder is cooled as described above, even if the cooling air passes through the lower holder, it will not be heated unnecessarily and reduce the cooling effect.

In addition to the above effects, the lower holder does not undergo thermal expansion, so the valve lifter can be properly held without the need for the clearance adjustment. Furthermore, thermal deterioration of the lower holder does not occur even if the thermal spraying process is continued.

[Example] Hereinafter, an example in which the present invention is embodied in a thermal spraying method and apparatus for an aluminum alloy valve lifter (same as the valve lifter 2 described in the prior art section) will be described with reference to FIG. do.

The thermal spray processing apparatus 1 of this embodiment includes an upper holder 2 and a lower holder 3, and a rotation drive device (not shown) that rotates the end wall 22 of the valve lifter 21 around an axis. and a thermal spray gun 4 disposed on the side of the side wall 23 of the valve lifter 21 so as to be movable up and down.

Here, the upper holder 2 may be a simple cylindrical member similar to those listed in the prior art section, or may be of any type as long as it holds the end wall 22. Furthermore, any known means such as an electric motor, a hydraulic motor, etc. can be used as the rotational drive device. Further, as the thermal spray gun 4, guns of various known methods such as flame thermal spraying, arc thermal spraying, plasma thermal spraying, etc. can be used.

Now, the feature of this embodiment lies in the lower holder 3, which is approximately circular with an outer diameter slightly smaller than the inner diameter of the side wall 23 of the two valve lifters so as to create a sufficient gap for air cooling between the side wall 23 of the two valve lifters. It is formed into a column.

The center portion of the upper surface of the lower holder 3 is flat so as to come into surface contact with the end wall 22 of the valve lifter 21, but around it is an inclined surface 5 that is lower on the peripheral edge side. Second slope 5
1 or 2 or more jet holes 6 which open diagonally outward toward the end wall 22 of the valve lifter 21 are formed in the lower holder 3, and the inside from the outer periphery of the lower holder 3 communicates with the jet holes 6 to supply cooling air. The number of air passages 7 through which the air passes through is formed according to the number of ejection holes 6. An air pump (not shown) is connected to this air passage 7, and is configured to send out cooling air at a pressure of, for example, 4 kgf/-. The temperature of this cooling air may be room temperature, but the air cooling effect can be further enhanced by cooling it to below room temperature.

Furthermore, the inner center of the lower holder 3 has a substantially circular cross section;
A cavity 8 with a closed upper end is formed, and a cylindrical cooling pipe 9 having an outer diameter smaller than the inner diameter of the cavity 8 is formed.
is arranged so as not to touch the top surface of the cavity 8. Therefore, from the inside of the cooling pipe 9 to the gap between the outer circumferential surface of the cooling pipe 9 and the inner circumferential surface of the cavity 8 constitutes a cooling water flow path l○ through which the cooling water passes. The entrance of this cooling water flow path l○,
That is, a water pump (not shown) is connected to the lower end of the cooling pipe 9. The temperature and pressure of this cooling water are preferably set to such a temperature and pressure that the lower holder 3 is maintained at around room temperature during the thermal spraying process described later. This is because when the lower holder 3 is cooled to a temperature considerably lower than room temperature during thermal spraying work, dew condenses on the outer surface of the lower holder 3.
This is because it causes the generation of water vapor, which may prevent a uniform sprayed layer from being obtained.

Next, a method of thermal spraying the valve lifter 21 using the thermal spraying apparatus 1 configured as described above will be described.

First, the end wall 22 of the valve lifter 21 is held between the upper holder 2 and the lower holder 3, and the gap between the inner circumferential surface of the side wall 23 and the lower holder 3 is made approximately equal over the entire circumference.

Next, while the valve lifter 21 is slowly rotated around its axis by a rotary drive device, a wear-resistant material is thermally sprayed onto the side wall 23 from a vertically moving thermal spray gun 4 set on the side of the valve lifter 21 to form a thermal spray 111. do. here,
The rotational speed of the valve lifter 21 is approximately 400 to 600 rpm, which is appropriate. In addition, in this example, N1Cr-B-3i alloy is used as the wear-resistant material, and the spraying temperature is approximately 10
The temperature was 00°C.

During the thermal spraying process and immediately after the thermal spraying process, the water pump is operated to pass cooling water through the cooling water flow F11110 of the lower holder 3, and the lower holder 3 is moved between the pallet lifter 2 and the lower holder 3 as described above.
Water cooling is performed to maintain the temperature around room temperature even when thermal spraying heat is conducted from 1. At the same time, the air pump is operated to blow out cooling air from the blow-off holes 6 of the lower holder 3 onto the inner surfaces of the end wall 22 and side wall 23 of the valve lifter 21, thereby air-cooling the valve lifter 21.

Therefore, the valve lifter 21 is effectively forcedly cooled by the following action.

(2) Heat from the spraying is quickly conducted from the valve lifter 21 to the lower holder 3, which is maintained at around room temperature during spraying due to the water cooling.

(2) The valve lifter 21 directly radiates heat due to the air cooling. At this time, since the lower holder 3 is maintained at around room temperature as described above, even if the cooling air passes through the lower holder 3, it will not be heated above the room temperature and reduce the cooling effect.

In addition to the above effects, since the lower holder 3 is maintained at around room temperature, there is no fear of generation of water vapor due to dew condensation, and a uniform sprayed layer can be obtained. Further, since the lower holder 3 does not undergo thermal expansion, the valve lifter 21 can be properly held without the need for the clearance adjustment. Furthermore, even if the thermal spraying process is repeated continuously, the lower holder 3
No thermal deterioration occurs.

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) The outer shape of the lower holder is not limited to a cylinder, but may be a square cylinder, for example.

(2) The cooling water flow path is not limited to the one formed by the cavity 8 and the cooling pipe 9, but may be formed by continuously forming holes, or by casting a curved cooling pipe into the lower holder. It could be something, etc. Further, the number of cooling water channels may be one or more or two or more.

(3) The position of the ejection hole is not limited to the inclined surface 5, and may be located at the upper side of the lower holder 3, for example. Further, the number of ejection holes may be one or two or more, but from the viewpoint of air cooling effect, two or more is preferable, and two to four are common.

(4) The air passage can also be changed as appropriate, similar to the cooling water passage. In addition, if two or more blowholes are provided,
The air passage may be shared halfway and then branched from the middle.

(5) The water cooling and air cooling may be performed at least during thermal spraying, but the cooling effect can be enhanced by performing them immediately after thermal spraying as in the embodiment.

(6) The cooling water flow path may be provided in the upper holder, and in this case, the effect of cooling the valve lifter due to heat conduction is further enhanced.

(7) The present invention can be applied to thermal spraying of valve lifters made of the aforementioned various light alloys in addition to aluminum alloys.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to form a uniform thermal spray layer without causing a decrease in the hardness of the light alloy valve lifter, and also to facilitate smooth thermal spraying processing. It has the excellent effect of being able to

[Brief explanation of drawings]

FIG. 1 is an actual sectional view of a thermal spray processing apparatus embodying the present invention, and FIG. 2 is a sectional view of a conventional example. 1...Thermal spray treatment equipment for direct impact type valve lifters, 2...
Upper holder, 3... Lower holder spout hole, 4...
Thermal spray gun, 6... Ejection hole, 7... Air passage, 8... Cavity as a cooling water flow path, 9... Cooling pipe as a cooling water flow path, 10... Cooling water flow path, 11. ...Thermal spray layer, 21...
・Valve lifter, 22... end wall, 23... (regular wall).

Claims (2)

[Claims] 1. The end wall (22) of an inverted cup-shaped valve lifter (21) made of light alloy is held between the upper holder (2) and the lower holder (3) and rotated around the axis. The valve lifter (21
A wear-resistant material is thermally sprayed onto the outer peripheral surface of the side wall (23) of the lower holder (23) to form a thermally sprayed layer (11), and at least during the thermal spraying, cooling water is passed through the lower holder (3). 3) is water-cooled, and the valve lifter (21) is air-cooled by jetting cooling air from the lower holder (3) to the valve lifter (21). 2. An upper holder (2) and a lower holder (3) that sandwich an end wall (22) of an inverted cup-shaped valve lifter (21) formed of a light alloy, and the upper holder (2) and the lower holder ( 3), and a thermal spray gun (4) disposed on the side of the side wall (23) of the valve lifter (21), the lower holder (3) includes an ejection hole (6) that opens toward the valve lifter (21), an air passage (7) that communicates with the ejection hole (6) and allows cooling air to pass through, and the lower holder (3).
) A thermal spraying treatment apparatus for a direct-type valve lifter, characterized in that a cooling water flow path (8, 9, 10) for passing cooling water is provided in the interior of the valve lifter.