Oppositely-combined type jet flow element

Abstract

The invention belongs to the technical field of jet-type hydraulic down-the-hole hammer drilling tools, and relates to an involution type jet-flow element which is formed by involution of a jet-flow element plate A and a jet-flow element plate B. The jet-flow element plate A and the jet-flow element plate B are of a mirror symmetry structure. And an input channel, a left signal channel, a left control channel, an upper cavity emptying channel, a right control channel, a right signal channel, an output channel, a lower cavity emptying channel, a main nozzle, a split wedge fixing screw hole, an involution plate fixing pin hole A and an involution plate fixing pin hole B. According to the invention, the processing difficulty is reduced, the processing period is shortened, the processing cost is reduced, and the production efficiency is improved. According to the flow channel with the small depth-to-width ratio, the stress of a stress concentration area is reduced, the jet element is promoted to adopt a hard alloy with a lower mark and higher erosion resistance, then the erosion resistance of the jet element is improved, the service life of the jet element is prolonged, the small-depth-to-width-ratio oppositely-combined jet element provides possibility for design and machining of the jet element with the ultra-large width-to-depth ratio, and the design cost is reduced. And enough strength redundancy is provided.

Description

Technical Field

[0001] The invention belongs to the technical field of jet - type hydraulic down - the - hole hammer drilling tools, and particularly relates to a mating jet element. Background Art

[0002] As a core component, the short service life and high cost of the jet element greatly limit the application and popularization of the jet - type hydraulic down - the - hole hammer. In the existing structure, the signal channels of the jet element are arranged on one side only. Its large depth - to - width ratio often leads to a decline in processing accuracy and an increase in manufacturing cost. At the same time, the overall strength is insufficient, especially manifested as the fracture phenomenon at the right - angled part at the bottom of the signal channel. In order to improve the overall strength of the element, compromises are often made in material selection. Therefore, hard alloy materials with a larger grade are usually selected, which in turn results in poor erosion resistance of the jet element. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a jet element that can improve the processing accuracy of the jet element, shorten the processing cycle, reduce the processing cost, and improve the strength and erosion resistance of the jet element.

[0004] To solve the above - mentioned technical problem, the technical solution of the present invention is as follows:

[0005] A mating jet element, as Figure 1 , Figure 2 shown, is formed by mating jet element plate A and jet element plate B. Jet element plate A and jet element plate B are mirror - symmetric structures to each other. On the mating surface of jet element plate A, there are an input channel, a left signal channel, a left control channel, an upper - cavity evacuation channel, a right control channel, a right signal channel, an output channel, a lower - cavity evacuation channel, a main nozzle, split - tip fixing screw holes, mating - plate fixing pin holes A, and mating - plate fixing pin holes B.

[0006] The main nozzle is a reduced - diameter throat structure on the mating surface of jet element plate A. This reduced - diameter throat structure is a funnel - shaped groove that is symmetric about the vertical axis on the mating surface of jet element plate A. A pair of through - holes, mating - plate fixing pin holes A, are symmetrically distributed on the left and right sides outside the main nozzle. A pair of through - holes, mating - plate fixing pin holes B, are symmetrically distributed on the outside below the mating - plate fixing pin holes A.

[0007] The left lower end of the main nozzle is connected to the upper right end of the left control channel. The left control channel and the right control channel are symmetric about the vertical axis on the mating surface of the jet element plate A. The left control channel is a straight groove, which is horizontal or inclined upward to the left, with a maximum inclination angle of 12°. The left end of the left control channel is connected to the right end of the left signal channel. The left signal channel includes three parts: an arc-shaped groove, a vertical groove, and an inclined straight groove. The part of the left signal channel connected to the left control channel is the arc-shaped groove. The center of the above-mentioned arc-shaped groove is located on the left side of the vertical axis of the mating surface of the jet element plate A. The arc-shaped groove can avoid the large energy loss caused by right-angle conversion, prevent the working frequency from decreasing due to untimely jet switching, and at the same time reduce the probability of easy damage of the hard alloy brittle material in the right-angle case. For the part of the above-mentioned arc-shaped groove far from the left control channel, when its tangent is a vertical straight line, the arc-shaped groove is connected to the upper end of the vertical groove. The lower end of the vertical groove is smoothly connected to one end of the inclined straight groove, and the other end of the inclined straight groove is connected to the input channel. The inclined straight groove is inclined upward to the left. The left signal channel and the right signal channel are symmetric about the vertical axis on the mating surface of the jet element plate A.

[0008] Preferably, the included angle between the vertical groove and the inclined straight groove is 120° - 160°.

[0009] Directly below the main nozzle is the working chamber, which is an isosceles trapezoidal groove structure symmetric about the vertical axis on the mating surface of the jet element plate A. The upper left end of the working chamber is connected to the lower right end of the left control channel. The lower left side of the working chamber is connected to the input channel, and the lower right side of the working chamber is connected to the output channel. The input channel and the output channel are symmetric about the vertical axis on the mating surface of the jet element plate A. The input channel includes a vertical channel and an inclined channel. The lower end of the vertical channel of the input channel starts from the bottom end of the jet element plate A. The upper left part of the vertical channel of the input channel is connected to the bottom end of the inclined straight groove of the aforementioned left signal channel. There is an upper cavity evacuation channel between the working chamber and the left signal channel. The upper cavity evacuation channel is a waist-shaped groove. The lower right part of the upper cavity evacuation channel is connected to the upper left part of the inclined channel of the aforementioned input channel. The lower cavity evacuation channel is symmetric about the vertical axis on the mating surface of the jet element plate A with the upper cavity evacuation channel. The jet diffusion angle is 24°.

[0010] Preferably, the included angle between the left control channel and the left side of the working chamber is 78° - 90°.

[0011] Preferably, the included angle between the left side of the working chamber and the center line of the main nozzle is greater than 24°.

[0012] Between the input channel and the output channel is a split wedge. There are through holes and split wedge fixing screw holes on the split wedge. The center of the split wedge fixing screw holes is located at the lower part of the longitudinal axis of the jet element plate A. There is an arc-shaped notch in the middle of the top of the split wedge, and two wedges are formed therefrom. The arc-shaped notch guides a small part of the fluid to form a vortex above the wedge, entraining a small part of the fluid on the non-wall-attached side, enhancing the stability of the wall-attached jet, increasing the energy of the main jet, and the wedge can prevent signal switching caused by the lower drill tool not reaching the end when the flow rate is too large, and can reduce sensitivity to a certain extent.

[0013] On the mating surface of the jet element plate A, except for the upper cavity drain channel and the lower cavity drain channel running through the front and back of the jet element plate A, the depths of the remaining grooves are the same.

[0014] Through the above design scheme, the present invention can bring the following beneficial effects:

[0015] (1) The present invention abandons the conventional single-sided channel design with a large depth-width ratio and changes to a symmetric mating jet element, reducing the depth of the single-sided channel by 50%, reducing the processing difficulty of numerical control milling, shortening the processing cycle, and reducing the processing cost.

[0016] (2) The small depth-width ratio channel of the present invention reduces the stress in the stress concentration area, prompting the jet element to use a harder alloy with a lower grade and stronger erosion resistance, thereby enhancing its erosion resistance and service life.

[0017] (3) The small depth-width ratio mating jet element provides the possibility for the design and processing of an ultra-large width-depth ratio jet element, giving it sufficient strength redundancy. Description of the Drawings

[0018] The following further describes the present invention in conjunction with the drawings and specific embodiments:

[0019] Figure 1 It is the front view of the jet element plate A of a mating jet element of the present invention.

[0020] Figure 2 It is the A-A sectional view of a mating jet element of the present invention.

[0021] In the figure, 1 - upper cavity drain channel, 2 - jet element plate A, 3 - left signal channel, 4 - jet element plate B, 5 - mating plate fixing pin hole B, 6 - lower cavity drain channel, 7 - right signal channel, 8 - mating plate fixing pin hole A, 9 - left control channel, 10 - right control channel, 11 - input channel, 12 - split wedge fixing screw hole, 13 - main nozzle, 14 - output channel, 15 - working chamber. Specific Embodiments

[0022] The technical solution of an opposed jet element of the present invention will be further described below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0023] Embodiment 1

[0024] An opposed jet element is formed by the opposed combination of a jet element plate A2 and a jet element plate B4. The jet element plate A2 and the jet element plate B4 are mirror-symmetric structures to each other. As Figure 1 and Figure 2 shown, on the opposed surface of the jet element plate A2, there are an input channel 11, a left signal channel 3, a left control channel 9, an upper cavity evacuation channel 1, a right control channel 10, a right signal channel 7, an output channel 14, a lower cavity evacuation channel 6, a main nozzle 13, a split wedge fixing screw hole 12, an opposed plate fixing pin hole A8, and an opposed plate fixing pin hole B5.

[0025] The main nozzle 13 is a constricted throat structure on the opposed surface of the jet element plate A2. This constricted throat structure is a funnel-shaped groove that is symmetric about the vertical axis on the opposed surface of the jet element plate A2; on the outer side of the main nozzle 13, a pair of through holes, the opposed plate fixing pin hole A8, are symmetrically distributed left and right. Below the outer side of the opposed plate fixing pin hole A8, a pair of through holes, the opposed plate fixing pin hole B5, are symmetrically distributed.

[0026] The left lower end of the main nozzle 13 is connected to the upper right end of the left control channel 9. The left control channel 9 and the right control channel 10 are symmetric about the vertical axis on the opposed surface of the jet element plate A2. The left control channel 9 is a horizontal straight groove. The left end of the left control channel 9 is connected to the right end of the left signal channel 3. The left signal channel 3 includes three parts: an arc-shaped groove, a vertical groove, and an inclined straight groove. The part of the left signal channel 3 connected to the left control channel 9 is an arc-shaped groove. The center of the above arc-shaped groove is located on the left side of the vertical axis of the opposed surface of the jet element plate A2. For the part of the above arc-shaped groove far from the left control channel 9, when its tangent is a vertical straight line, the arc-shaped groove is connected to the upper end of the vertical groove. The lower end of the vertical groove is smoothly connected to one end of the inclined straight groove. The included angle between the vertical groove and the inclined straight groove is 120°. The other end of the inclined straight groove is connected to the input channel 11. The inclined straight groove slopes upward to the left. The left signal channel 3 and the right signal channel 7 are symmetric about the vertical axis on the opposed surface of the jet element plate A2.

[0027] Directly below the main nozzle 13 is the working chamber 15, which is an isosceles trapezoidal groove structure that is symmetric about the vertical axis on the mating surface of the jet element plate A2. The upper left end of the working chamber 15 communicates with the lower right end of the left control channel 9; the lower left side of the working chamber 15 communicates with the input channel 11, and the lower right side of the working chamber 15 communicates with the output channel 14. The input channel 11 and the output channel 14 are symmetric about the vertical axis on the mating surface of the jet element plate A2. The input channel 11 includes a vertical channel and an inclined channel. The lower end of the vertical channel of the input channel 11 starts from the bottom end of the jet element plate A2, and the upper left part of the vertical channel of the input channel 11 communicates with the bottom end of the oblique straight groove of the aforementioned left signal channel 3; there is an upper cavity evacuation channel 1 between the working chamber 15 and the left signal channel 3. The upper cavity evacuation channel 1 is a waist-shaped groove. The lower right part of the upper cavity evacuation channel 1 communicates with the upper left part of the inclined channel of the aforementioned input channel 11. The lower cavity evacuation channel 6 is symmetric about the vertical axis on the mating surface of the jet element plate A2 with the upper cavity evacuation channel 1. The jet diffusion angle is 24°, the included angle between the left control channel 9 and the left side of the working chamber 15 is 78°, and the included angle between the left side of the working chamber 15 and the center line of the main nozzle 13 is greater than 24°.

[0028] Between the input channel 11 and the output channel 14 is a split split tip. There is a through-hole split split tip fixing screw hole 12 on the split split tip. The center of the split split tip fixing screw hole 12 is located at the lower part of the vertical axis of the jet element plate A2. There is a circular arc notch in the middle of the top of the split split tip, and two split tips are formed therefrom.

[0029] Except for the upper cavity evacuation channel 1 and the lower cavity evacuation channel 6 that penetrate through the front and back of the jet element plate A2 on the mating surface of the jet element plate A2, the depths of the remaining grooves are the same.

[0030] Embodiment 2

[0031] An opposed jet element is formed by the mating of a jet element plate A2 and a jet element plate B4. The jet element plate A2 and the jet element plate B4 are mirror-symmetric structures to each other. As Figure 1 and Figure 2 shown, on the mating surface of the jet element plate A2, there are an input channel 11, a left signal channel 3, a left control channel 9, an upper cavity evacuation channel 1, a right control channel 10, a right signal channel 7, an output channel 14, a lower cavity evacuation channel 6, a main nozzle 13, a split split tip fixing screw hole 12, a mating plate fixing pin hole A8, and a mating plate fixing pin hole B5.

[0032] The main nozzle 13 is a reduced throat structure on the mating surface of the jet element plate A2. This reduced throat structure is a funnel-shaped groove that is symmetric about the vertical axis on the mating surface of the jet element plate A2; on the outer side of the main nozzle 13, a pair of mating hole mating plate fixing pin holes A8 are symmetrically distributed, and on the outer side below the mating plate fixing pin holes A8, a pair of mating hole mating plate fixing pin holes B5 are symmetrically distributed.

[0033] The lower left end of the main nozzle 13 is connected to the upper right end of the left control channel 9. The left control channel 9 and the right control channel 10 are symmetric about the vertical axis on the mating surface of the jet element plate A2. The left control channel 9 is a straight groove inclined upward to the left, with an inclination angle of 12°. The left end of the left control channel 9 is connected to the right end of the left signal channel 3. The left signal channel 3 includes three parts: an arc-shaped groove, a vertical groove, and an inclined straight groove. The part of the left signal channel 3 connected to the left control channel 9 is an arc-shaped groove. The center of the above arc-shaped groove is located on the left side of the vertical axis of the mating surface of the jet element plate A2. For the part of the above arc-shaped groove far from the left control channel 9, when its tangent is a vertical straight line, the arc-shaped groove is connected to the upper end of the vertical groove. The lower end of the vertical groove is smoothly connected to one end of the inclined straight groove. The included angle between the vertical groove and the inclined straight groove is 160°. The other end of the inclined straight groove is connected to the input channel 11. The inclined straight groove is inclined upward to the left. The left signal channel 3 and the right signal channel 7 are symmetric about the vertical axis on the mating surface of the jet element plate A2.

[0034] Directly below the main nozzle 13 is the working chamber 15. The working chamber 15 is an isosceles trapezoidal groove structure symmetric about the vertical axis on the mating surface of the jet element plate A2. The upper left end of the working chamber 15 is connected to the lower right end of the left control channel 9; the lower left side of the working chamber 15 is connected to the input channel 11, and the lower right side of the working chamber 15 is connected to the output channel 14. The input channel 11 and the output channel 14 are symmetric about the vertical axis on the mating surface of the jet element plate A2. The input channel 11 includes a vertical channel and an inclined channel. The lower end of the vertical channel of the input channel 11 starts from the bottom end of the jet element plate A2. The upper left part of the vertical channel of the input channel 11 is connected to the bottom end of the inclined straight groove of the aforementioned left signal channel 3; there is an upper cavity evacuation channel 1 between the working chamber 15 and the left signal channel 3. The upper cavity evacuation channel 1 is a waist-shaped groove. The lower right part of the upper cavity evacuation channel 1 is connected to the upper left part of the inclined channel of the aforementioned input channel 11. The lower cavity evacuation channel 6 and the upper cavity evacuation channel 1 are symmetric about the vertical axis on the mating surface of the jet element plate A2. The jet diffusion angle is 24°. The included angle between the left control channel 9 and the left side of the working chamber 15 is 90°. The included angle between the left side of the working chamber 15 and the center line of the main nozzle 13 is greater than 24°.

[0035] Between the input channel 11 and the output channel 14 is a split wedge tip. There are through holes and split wedge tip fixing screw holes 12 on the split wedge tip. The center of the split wedge tip fixing screw holes 12 is located at the lower part of the vertical axis of the jet element plate A2. There is an arc-shaped notch in the middle of the top of the split wedge tip, and two wedge tips are formed therefrom.

[0036] Except for the upper cavity evacuation channel 1 and the lower cavity evacuation channel 6 that penetrate the front and back of the jet element plate A2 on the mating surface of the jet element plate A2, the depths of the remaining grooves are the same.

[0037] Embodiment 3

[0038] An involute jet element is formed by the involution of jet element plate A2 and jet element plate B4. Jet element plate A2 and jet element plate B4 are mirror-symmetric structures to each other. As Figure 1 and Figure 2 shown, on the involution surface of jet element plate A2, there are input channel 11, left signal channel 3, left control channel 9, upper cavity evacuation channel 1, right control channel 10, right signal channel 7, output channel 14, lower cavity evacuation channel 6, main nozzle 13, split wedge fixing screw hole 12, involute plate fixing pin hole A8, and involute plate fixing pin hole B5.

[0039] The main nozzle 13 is a constricted throat structure on the involution surface of jet element plate A2. This constricted throat structure is a funnel-shaped groove that is symmetric about the vertical axis on the involution surface of jet element plate A2; on the outside of the main nozzle 13, a pair of involute plate fixing pin holes A8 are symmetrically distributed on the left and right. Below the outside of the involute plate fixing pin hole A8, a pair of involute plate fixing pin holes B5 are symmetrically distributed.

[0040] The left lower end of the main nozzle 13 is connected to the upper right end of the left control channel 9. The left control channel 9 and the right control channel 10 are symmetric about the vertical axis on the involution surface of jet element plate A2. The left control channel 9 is a straight groove inclined upward to the left, with an inclination angle of 6°. The left end of the left control channel 9 is connected to the right end of the left signal channel 3. The left signal channel 3 includes three parts: an arc-shaped groove, a vertical groove, and an inclined straight groove. The part of the left signal channel 3 connected to the left control channel 9 is an arc-shaped groove. The center of the above arc-shaped groove is located on the left side of the vertical axis of the involution surface of jet element plate A2. For the part of the above arc-shaped groove far from the left control channel 9, when its tangent is a vertical straight line, the arc-shaped groove is connected to the upper end of the vertical groove. The lower end of the vertical groove is smoothly connected to one end of the inclined straight groove. The included angle between the vertical groove and the inclined straight groove is 140°. The other end of the inclined straight groove is connected to the input channel 11. The inclined straight groove is inclined upward to the left. The left signal channel 3 and the right signal channel 7 are symmetric about the vertical axis on the involution surface of jet element plate A2.

[0041] Below the main nozzle 13 is the working chamber 15, which is an isosceles trapezoidal groove structure that is symmetric about the vertical axis on the mating surface of the jet element plate A2. The upper left end of the working chamber 15 communicates with the lower right end of the left control channel 9; the left side of the lower end of the working chamber 15 communicates with the input channel 11, and the right side of the lower end of the working chamber 15 communicates with the output channel 14. The input channel 11 and the output channel 14 are symmetric about the vertical axis on the mating surface of the jet element plate A2. The input channel 11 includes a vertical channel and an inclined channel. The lower end of the vertical channel of the input channel 11 starts from the bottom end of the jet element plate A2, and the upper left part of the vertical channel of the input channel 11 communicates with the bottom end of the inclined straight groove of the aforementioned left signal channel 3; there is an upper cavity drain channel 1 between the working chamber 15 and the left signal channel 3. The upper cavity drain channel 1 is a kidney-shaped groove. The lower right part of the upper cavity drain channel 1 communicates with the upper left part of the inclined channel of the aforementioned input channel 11. The lower cavity drain channel 6 is symmetric about the vertical axis on the mating surface of the jet element plate A2 with the upper cavity drain channel 1. The jet diffusion angle is 24°, the included angle between the left control channel 9 and the left side of the working chamber 15 is 84°, and the included angle between the left side of the working chamber 15 and the center line of the main nozzle 13 is greater than 24°.

[0042] Between the input channel 11 and the output channel 14 is a split wedge tip. There is a through hole split wedge tip fixing screw hole 12 on the split wedge tip. The center of the split wedge tip fixing screw hole 12 is located at the lower part of the vertical axis of the jet element plate A2. There is a circular arc notch in the middle of the top of the split wedge tip, and thus two wedge tips are formed.

[0043] Except for the upper cavity drain channel 1 and the lower cavity drain channel 6 that penetrate the front and back of the jet element plate A2 on the mating surface of the jet element plate A2, the depths of the remaining grooves are the same.

Claims

1. A combined jet element, characterized in that: The invention comprises a jet element plate A (2) and a jet element plate B (4), wherein the jet element plate A (2) and the jet element plate B (4) are mirror-symmetrical structures, and the mating surface of the jet element plate A (2) is provided with an input channel (11), a left signal channel (3), a left control channel (9), an upper cavity emptying channel (1), a right control channel (10), a right signal channel (7), an output channel (14), a lower cavity emptying channel (6), a main nozzle (13), a split-split tip fixing screw hole (12), a mating plate fixing pin hole A (8), and a mating plate fixing pin hole B (5); The main nozzle (13) is a constricted throat structure on the mating surface of the jet element plate A (2), and the constricted throat structure is a funnel-shaped groove on the mating surface of the jet element plate A (2) that is symmetrical about the longitudinal axis. A pair of symmetrically arranged symmetrically on the outer side of the main nozzle (13) are symmetrically arranged for mating plate fixing pin holes A (8), and a pair of symmetrically arranged symmetrically on the outer side below the mating plate fixing pin holes A (8); The lower left end of the main nozzle (13) is connected to the upper right end of the left control channel (9). The left control channel (9) and the right control channel (10) are symmetrical about the longitudinal axis on the matching surface of the jet element plate A (2). The left control channel (9) is a straight groove. The left control channel 9 is deflected horizontally or to the upper left, and the maximum deflection angle is 12°. The left end of the left control channel (9) is connected to the right end of the left signal channel (3). The left signal channel (3) includes three parts: a circular arc groove, a vertical groove, and an oblique straight groove. The part of the left signal channel (3) connected to the left control channel (9) is a circular arc groove. The center of the arc-shaped groove is located on the left side of the longitudinal axis of the matching surface of the jet element plate A (2). When the tangent of the arc-shaped groove is a vertical straight line, the arc-shaped groove is connected to the upper end of the vertical groove, the lower end of the vertical groove is smoothly connected to one end of the oblique straight groove, and the other end of the oblique straight groove is connected to the input channel (11). The oblique straight groove is inclined to the upper left, and the oblique straight groove is vertically inclined to the left. The left signal channel (3) and the right signal channel (7) are symmetrical about the longitudinal axis on the matching surface of the jet element plate A (2). Directly below the main nozzle (13) is a working chamber (15), which is an isosceles trapezoidal groove structure symmetrical about the longitudinal axis on the mating surface of the jet element plate A (2), the upper left end of the working chamber (15) is connected to the lower right end of the left control channel (9); the lower left end of the working chamber (15) is connected to the input channel (11), and the lower right end of the working chamber (15) is connected to the output channel (14), the input channel (11) and the output channel (14) are symmetrical about the longitudinal axis on the mating surface of the jet element plate A (2), the input channel (11) includes a vertical channel and an inclined channel, and the lower end of the vertical channel of the input channel (11) is connected to the output channel (14). At the bottom end of the jet element plate A (2), the upper left portion of the vertical channel of the input channel (11) is connected to the bottom end of the oblique straight groove of the aforementioned left signal channel (3); an upper cavity emptying channel (1) is provided between the working chamber (15) and the left signal channel (3); the upper cavity emptying channel (1) is a waist-shaped groove; the lower right portion of the upper cavity emptying channel (1) is connected to the upper left portion of the inclined channel of the aforementioned input channel (11); the lower cavity emptying channel (6) and the upper cavity emptying channel (1) are symmetrical about the longitudinal axis on the mating surface of the jet element plate A (2); the jet diffusion angle is 24°, and the angle between the left side of the working chamber 15 and the center line of the main nozzle 13 is greater than 24°; A split split tip is provided between the input channel (11) and the output channel (14). The split split tip has a through hole (12) for fixing the split split tip. The center of the split split tip fixing screw hole (12) is located below the longitudinal axis of the jet element plate A (2). There is an arc-shaped notch in the middle of the top of the split split tip, thereby forming two split tips. Except for the upper cavity emptying channel (1) and the lower cavity emptying channel (6) on the mating surface of the jet element plate A (2) which penetrate the front and back of the jet element plate A (2), the other grooves have the same depth.

2. A combined jet element according to claim 1, characterized in that: The angle between the left control channel (9) and the left side of the working chamber (15) is 78° to 90°.

3. The combined jet element according to claim 1, characterized in that: The included angle between the vertical groove and the oblique groove is 120° to 160°.

4. The combined jet element according to claim 1, characterized in that: The jet element plate A (2) and the jet element plate B (4) are made of YG25 steel.

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