JPH0549386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an overlay welding device, and particularly to a technique for efficiently overlaying an engine valve.

PRIOR ART In an engine valve having a shaft portion and a seated valve portion formed with a large diameter at one end thereof, a valve seat is disposed approximately vertically in a relatively shallow annular groove formed on the seating surface of the valve portion. Overlay welding is performed using a plasma arc torch. In the subsequent finishing process, the surface layer of the overlay formed on the seating surface of the valve part is removed along with the rest of the valve part to give it a predetermined shape, and the seating part is made of a highly durable material that is overlay welded. Configure. That is, in order to increase the durability of the seating surface of the engine valve, welding is performed locally using a highly durable metal material prior to the finishing process.

However, with conventional overlay welding equipment, when finish processing is applied to engine valves,
A large amount of the surface layer of the fillet was removed, and a sufficient yield of the expensive material constituting the fillet was not necessarily obtained.

On the other hand, as described in Japanese Utility Model Application Publication No. 58-143063, it has been proposed to tilt the center line of the engine valve so that the part to be overlaid is placed in a horizontal state. In this way, the molten metal heaped up by the plasma arc torch becomes symmetrical with respect to the center of the width in the width direction of the annular groove, so that an appropriate amount of metal buildup can prevent underfilling. At the same time, the amount of surface layer cutting is reduced and the material yield is improved.

Problems to be Solved by the Invention By the way, in the conventional overlay welding apparatus described above, if the arc emitted from the plasma arc torch together with the overlay material is too thin, the overlay cannot sufficiently cover the width of the annular groove. , there was a drawback that insufficient build-up occurred in the width direction. On the other hand, if the arc emitted from the plasma arc torch along with the overlay material is made thicker, the welding of the base metal will increase the amount of melted parts, and the hardness of the overlay will decrease due to the welding of the base metal. Ta.

Means for Solving the Problems The present invention has been made against the background of the above circumstances, and its gist is to provide an engine valve having a shaft portion and a valve portion formed with a large diameter at one end thereof. , an overlay welding device for performing overlay welding on a relatively shallow annular groove formed in the seating surface of the valve portion using a overlay plasma arc torch disposed in a substantially vertical direction, The engine valve is held in a state where its axis is inclined at an angle of 10 to 60 degrees with respect to the vertical line, and the annular groove of the engine valve is positioned below the plasma arc torch. A valve holding drive device that rotates around the shaft is installed,
Furthermore, the nozzle diameter of the plasma arc torch is set to 0.6 to 1.3 times the width of the annular groove.

Operation and Effects of the Invention As a result, the axis of the engine valve is tilted at an angle of 10 to 60 degrees with respect to the vertical line.
This prevents the build-up from being unevenly distributed on the end face side of the valve portion and causing underfill, and the amount of cutting of the fill-up surface layer during finishing is gradually reduced. Moreover, since the nozzle diameter of the plasma arc torch is set to be 0.6 to 1.3 times the width of the annular groove, the width of the annular groove caused by the arc emitted from the plasma arc torch together with the overlay material is too narrow. This solves the problem that the hardness of the build-up decreases due to an increase in the amount of penetration of the base material due to insufficient build-up in the direction or an arc that is too thick.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 3 is a schematic plan view showing the entire engine valve overlay welding device, and 10 is a turntable. On the outer periphery of the turntable, a plurality of grippers 12 (six in this embodiment) are arranged at equal angular intervals in the circumferential direction. Turntable 1
0 is designed to be rotated intermittently every 120 degrees by a drive device (not shown), and a pair of grippers 1
2 is arranged to be sequentially positioned to a supply position, a build-up position, and a discharge position. That is, the turntable 10 and the gripper 12 constitute a handling device that sequentially moves the engine valve 20 from the supply position to the build-up position and to the discharge position.

As shown in FIG. 4, the gripper 12 includes a first arm 14 projecting from the turntable 10;
A second arm 16 pivotable about a horizontal axis perpendicular to the longitudinal direction of its first arm 14
and a pair of clamping pieces 18 which are provided at the distal end of the second arm 16 so as to be relatively rotatable around a vertical axis, and which are constantly biased in a direction toward each other. A groove 24 for clamping the shaft portion 22 of the engine valve 20 and a tapered surface 26 extending from the tip end to the groove 24 are formed on the facing surface of the clamping piece 18, so that the shaft portion 22 of the engine valve 20 can be gripped. When pushed along both tapered surfaces 26, the engine valve 20 is clamped, and the engine valve 20 is forcibly pressed against the clamping piece 18.
The engine valve 20 is removed from the gripper 12 by being driven in the distal direction.

Returning to FIG. 3, the engine valves 20 are guided along an inclined supply rail 28 so as to be fed in line to a pair of reversing devices 30 provided at the feeding position. . Fifth
As shown in detail in the figure, the reversing device 30 includes a reversing drive device 3 that drives the bracket 32 to reciprocate by 180 degrees.
It is equipped with 4. At the tip of the bracket 32,
A pair of pawls 38 are provided at the shaft end of the engine valve 20 and engage with a large diameter valve portion 36 to latch the engine valve 20, and the engine valve is latched to the pawls 38. A pressing member 40 that is movably provided so as to be able to press the 20 valve parts 36, and a holding cylinder 42 that drives the pressing member 40 to hold the engine valve 20.
and is provided. FIG. 5 shows a state in which one engine valve 20 supplied from the supply rail 28 is sent to the reversing device 30 and latched on the claw 38 by means of a gate means (not shown), and is then latched by the holding cylinder 42. The engine valve 20 is held by the bracket 32 by pressing the pressing member 40 against the valve portion 36 of the engine valve 20. After that, the reversing drive device 34 causes the fifth
At the same time as the bracket 32 is driven to the position shown by the imaginary line in the figure, the engine valve 20 held by the bracket 32 is gripped by the gripper 12. That is, the reversing device 30, the supply rail 28, and the like constitute an engine valve supply device that supplies the engine valve to the gripper 12 in a constant posture. Note that the reversing drive device 34 also drives the bracket 32 in the direction of its rotational axis, and in order to prevent interference between the pawls 38 and the engine valve 20, the reversing drive device 34 is configured to drive the bracket 32 in the direction of its rotation axis. After the bracket 32 is moved toward its center of rotation and the pawl 38 is pulled out from the engine valve 20, it is rotated (returning).

As described above, the gripper 12 at the supply position
The engine valve 20 gripped by the engine valve 20 is transported to the overlay position as the turntable 10 is rotated at a constant angle (120° in this embodiment). Then,
The second arm 16 of the gripper 12 is
When tilted by a predetermined angle within the angle range of 10° to 60°, the engine valve 20
is tilted and overlay welding is started. As shown in detail in FIG. 6, a rotary drive device 46 equipped with a welding base 44 is raised by a lifting device (not shown), and the end of the shaft portion 22 of the engine valve 20 is rotated by the rod of the holding cylinder 42. When pressed in the axial direction toward the drive device 46, the end face of the valve portion 36 of the engine valve 20 is brought into contact with the welding base 4.
A relatively shallow annular groove 52 closely attached to the central portion of the plasma arc torch 50 and formed in the conical surface of the valve portion 36 is positioned below the lowered plasma arc torch 50. That is, the engine valve 20 is held in an inclined state by the welding base 44, rotation drive device 46, and pressing cylinder 48 that constitute the valve holding drive device, and is rotated around the axis. be. The plasma arc torch 50 is held by a torch holder 54 approximately vertically, that is, at a predetermined angle within an angular range of plus or minus 15 degrees with respect to the vertical line, and between a raised position and a lowered position. It is designed so that it can be raised and lowered. FIG. 6 shows the lowered position of the plasma arc torch 50. Note that a cooling passage 56 is formed in the welding base 44 for passing a cooling liquid.

Then, the engine valve 20 is rotated by the rotary drive device 4.
6 rotates one rotation around the axis, overlay welding is performed on the annular groove 52 of the valve portion 36 by the plasma arc torch 50. In the plasma arc torch 50, for example, as shown in FIG. 7, a rod-shaped electrode 58 is inserted into a torch inner cylinder 60, and the torch inner cylinder 60 is inserted into a torch outer cylinder 62.
By being inserted therein, annular passages 64 and 66 are formed between the electrode 58 and the torch inner cylinder 60 and between the torch inner cylinder 60 and the torch outer cylinder 62, respectively. Plasma gas is supplied into the passage 64 from a gas source 68, and a welding material supply device 7 is provided in the passage 66.
Powder carrier gas containing powdered welding material 74 is supplied from 0 through a pair of pipes 72 . This welding material 74 is, for example, -60
The material has a mesh size of about 300 to 300 mesh, and is a CO-based stellite type or a nickel-based colmonoy type.

A high frequency power source 76 is connected between the electrode 58 and the torch inner cylinder 60, and when a high frequency current is supplied thereto, a pilot arc is formed between them and the plasma gas supplied from the gas source 68 is generated. is turned into plasma and discharged from the nozzle of the torch inner cylinder 60. A main power source 78 is connected between the electrode 58 and the welding base 44, and by supplying a welding current, the plasma drawn from the torch inner cylinder 60 is transferred to create a steady plasma arc. Between the electrode 58 and the valve part 36 of the engine valve 20, more precisely, the torch outer cylinder 6
It is formed between the annular groove 52 and the annular groove 52 located directly below the nozzle 80 of No. 2. When the powdered welding material 74 supplied from the welding material supplying device 70 is introduced into this plasma arc, the welding material 74 is melted by the plasma arc, and the annular groove 52 is melted by the plasma arc.
It is overlay welded onto the inner surface of the In the figure, 82 is a cooling water passage for cooling the tip of the plasma arc torch 50, 84 is a resistor, 86 is a distributor, and 88 is a carrier gas source.
The gas source in FIG. 3 includes the gas source 68 and the carrier gas source 88, and the power source in FIG. 3 includes the high frequency power source 76 and the main power source 7.
8.

Here, the nozzle of the plasma arc torch 50,
In other words, the diameter D of the nozzle 80 of the torch outer cylinder 62
is the width dimension W of the annular groove 52 to which overlay welding is to be performed.
It is set within the range of 0.6 times to 1.3 times. If the diameter D of the nozzle 80 is less than 0.6 times the width W of the annular groove 52, the filler 90 will not be able to sufficiently cover the width of the annular groove 52, resulting in insufficient thickness. If the diameter D of the nozzle 80 exceeds 1.3 times the width W of the annular groove 52, there will be a large amount of melted portion of the base material (valve portion 36) due to welding, and the hardness of the fill will decrease due to this. I end up.

Further, as shown in FIG. 8, in the plasma arc torch 50, the annular groove 52 belonging to the region E in the upstream half in the rotational direction in the upper half of the inclined valve part 36 is located below the plasma arc torch 50. It is set as follows. Therefore, since the welding position by the plasma arc torch 50 is relatively directed toward the descending plate, the penetration 92 of the base metal becomes shallower, and the build-up 90 tends to become thicker, as shown in FIG. 9, which is an advantage. There is. Note that the position of the nozzle 80 of the plasma arc torch 50 within the region E is appropriately determined according to the rotational speed and inclination of the engine valve 20.

In addition, engine valve 2 in overlay welding equipment
0 is inclined within the range of 10° to 60° with respect to the vertical line, but if this angle range is exceeded, the fillet 90 is likely to be biased and underfilling occurs, and the fillet 90
It becomes difficult to reduce the amount of cutting in the finishing process.
That is, as shown in FIGS. 1 and 2, the end face of the valve portion 36 of the engine valve 20 is generally a plane perpendicular to the axial direction, and the annular groove 52
The groove face K is formed at an angle of 45°±5° with respect to this end face. Then, the welded fillet 90 in the annular groove 52 is formed so as to be higher than the groove surface (the surface connecting the opening edges of the annular groove 52) K, and then the finished surface S is shaped as shown by the broken line. It is then finished through finishing processes such as cutting. Therefore, the shape of the fillet 90 only needs to be formed so as to bulge out slightly from the finished surface S shown by the broken line. This finished surface S is generally bulged toward the end face side with respect to the center of the annular groove 52 in the width direction. It is efficient to allow a large amount of bulge on the end face side. FIG. 1 shows a case where the engine valve 20 is tilted by 10 degrees with respect to the vertical line, that is, the valve portion 36
The fillet 90 is shown in a state where the angle α of the end face with respect to the horizontal line is 10°. The fillet 90 at this time is smaller than the fillet formed symmetrically with respect to the widthwise center portion of the annular groove 52 by the portion indicated by A, and the portion corresponding to A. The yield of the welding material 74 is improved, and the efficiency in finishing is increased. At this time, the angle of the groove surface K with respect to the horizontal plane is
35 degrees, and the plasma arc torch 50 is preferably set within an angular range B of 15 degrees vertically or to the left. The inclination angle of the engine valve 20
If the angle is less than 10°, the shape of the fillet 90 will be too biased due to gravity, causing the shaft portion 2 in the width direction of the annular groove 52 to
The 2nd side will be inside the finished surface S. FIG. 2 shows the shape of the fillet 90 when the engine valve 20 is inclined at 60° with respect to the vertical line, that is, when the angle α of the end face of the valve portion 36 with respect to the horizontal line is inclined at 60°. If the engine valve 20 is closed at this angle of 60 degrees or more, the thickness will be 90.
The shape is too biased, and the end surface side of the annular groove 52 in the width direction is inside the finished surface S. At this time, the torch 50 is set within a range B' of 15 degrees to the right from the vertical position, as shown in FIG. In addition,
The angle of the groove surface K at this time is 15° with respect to the horizontal line.
It is. Even at such an angle, there is a large amount of build-up from the widthwise center of the annular groove 52 of the build-up 90 to the end face side of the valve portion 36, but this is because the build-up in the fused state is caused by the gas ejected from the plasma arc torch 50. This is because 90 is pressed toward the end face side. Note that even when the groove surface K is horizontal due to the inclination of the engine valve 20 (approximately 45 degrees), the plasma arc torch 5 is
It is desirable to slope 0 within the range of B'.

When the engine valve 20 is rotated once around the axis by the rotary drive device 46 and overlay welding is completed, the plasma arc torch 50 is raised and the welding base 44 is lowered in accordance with the reverse operation. and the pressure from the pressure cylinder 48 is released. The second arm 16 of the gripper 12 is then returned to its original horizontal position. Thereafter, by rotationally driving the turntable 10, the overlay welded engine valve 20 is transported to the unloading position. At the unloading position, a reversing device 94 configured in exactly the same manner as the above-described reversing device 30 is provided, and the engine valve 20, which has completed overlay welding, is gripped by the gripper 12 by the reversing device 94. is held and reversed so that the engine valve 20
is removed from gripper 12.

The series of operations described above is controlled by the control device 96, and by repeatedly performing such operations, overlay welding is continuously and efficiently performed on the engine valve 20.

As described above, according to this embodiment, the annular groove of the valve portion 36 is formed by rotating the engine valve 20 around the axis while being inclined within the range of 10° to 60° with respect to the vertical line. Since overlay welding is performed on the overlay 52, the overlay 90 can be formed in a state slightly protruding from the finished surface S while preventing underfilling of the overlay 90. Therefore, the yield of welding material 74 is improved, the finishing process is performed efficiently, and wear and tear on cutting tools and the like is reduced.

In addition, the nozzle diameter D of the plasma arc torch 50
is set within a range of 0.6 to 1.3 times the width W of the annular groove 52, which prevents insufficient fill in the width direction of the annular groove 52 and suppresses the amount of penetration of the base material. This has the advantage that the hardness of the fillet is maintained.

In addition, the welding position directly below the plasma arc torch 50 is a position where the welding part 90 in a fluid state is inclined so as to flow downward facing the rotational direction of the engine valve 20, so that the welding position is deep in the base metal. is suitably suppressed. Therefore, in this respect as well, the hardness of the fill 90 is prevented from decreasing.

Further, according to this embodiment, the engine valve 20
The engine valve 20 is transported from the engine valve supply device to the valve holding drive device by the handling device, and the engine valve 20 after overlay welding is automatically transported to the unloading position by the handling device. Overlay welding is performed on the valve 20.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be applied to other aspects.

For example, in the embodiment described above, a pair of grippers 12 are configured to be simultaneously positioned at the supply position, the welding position, and the unloading position, but it is also possible to use only one gripper, or three or more grippers 12 may be positioned at the same time. Alternatively, instead of the turntable 10, a conveyor or a robot arm equipped with a gripping device for gripping the engine valve 20 may be used. In the case where one gripping device is attached to the tip of the robot arm, the gripping piece 18 of the gripper 12 may be driven to open and close. In this way, the reversing device 30,
94 etc. becomes unnecessary.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIGS. 1 and 2 are sectional views of essential parts of an engine valve welded by overlay welding using an apparatus according to an embodiment of the present invention. FIG. 3 is a schematic plan view showing an apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view of essential parts of the gripper shown in FIG. 3. FIG. 5 is a diagram illustrating the reversing device of FIG. 3. FIG. 6 is a diagram illustrating the valve holding and driving device shown in FIG. 3. FIG. 7 is a diagram illustrating the plasma arc torch of FIG. 3 and its auxiliary equipment. FIG. 8 is a diagram illustrating the welding position of the plasma arc torch shown in FIG. 6 with respect to the valve portion of the engine valve. FIG. 9 is a diagram illustrating overlay welding according to the conditions shown in FIG. 8. {10... turntable, 12... gripper} (handling device), 20... engine valve, {28... supply rail, 30... reversing device}
(engine valve supply device), 36...valve section, {4
4...Welding base, 46...Rotary drive device, 48
...Press cylinder} (valve holding drive device), 50
... Plasma arc torch, 52 ... Annular groove.

Claims (1)

[Scope of Claims] 1. In an engine valve having a shaft portion and a valve portion formed with a large diameter at one end thereof, a relatively shallow annular groove formed in the seating surface of the valve portion is provided with a substantially vertical groove. An overlay welding device that performs overlay welding using a disposed overlay plasma arc torch, wherein the engine valve is in a state where its axis is inclined at an angle of 10 to 60 degrees with respect to a vertical line. A valve holding and driving device is provided to rotate the engine valve around an axis while holding the engine valve in such a manner that the annular groove of the engine valve is positioned below the plasma arc torch, and furthermore, the nozzle diameter of the plasma arc torch is adjusted to the An overlay welding device characterized in that the width is 0.6 to 1.3 times the width of the annular groove.