A liquid rocket engine thrust chamber positioning fixture

Abstract

A liquid rocket engine thrust chamber positioning fixture comprises a transmission part and a positioning part. The transmission part includes a chuck, a drive shaft, a drive screw, and a hook key. The positioning part includes positioning claws, a column, a transmission cylinder, a guide sleeve, a positioning plate, and a spring. During operation, the column first positions the positioning fixture against the worktable. The thrust chamber is then placed on the positioning fixture, and the supporting claws of the positioning plate fix the thrust chamber in the appropriate position, completing the first positioning step. The drive shaft of the worktable meshes with the drive screw, and the rotational motion of the drive shaft is transmitted to the drive shaft through the drive screw, causing the positioning claws on the chuck to move at a constant speed along the radial direction, thereby tightening the throat of the engine thrust chamber, completing the second positioning step. By positioning the thrust chamber at these two points, the thrust chamber axis is aligned. This invention is widely used in positioning and alignment of sheet metal forming parts and brazed forming parts, offering advantages such as ingenious structure, ease of use, and strong adaptability.

Description

Technical Field

[0001] This invention relates to a positioning fixture for the thrust chamber of a liquid rocket engine, which is used for aligning the central axis of sheet metal parts and brazed parts such as the thrust chamber of a liquid rocket engine, as well as for scribing and measuring the conical nozzle of the thrust chamber. Background Technology

[0002] The thrust chamber, as the core component of a liquid rocket engine, comprises multiple independent assemblies. These assemblies are primarily connected by welding, and each assembly requires both assembly and welding. Due to the specialized manufacturing process of the thrust chamber, the assembly of its components largely employs a fit-fit method, involving final machining of the mating surfaces based on measured data to achieve precise assembly. Furthermore, to ensure assembly accuracy, the main assembly components must have positioning references matching the installation precision, and are also assembled, positioned, and welded using dedicated positioning fixtures. After assembly, the external interface dimensions of the thrust chamber must be measured. The relative positions and interface dimensions of these components directly affect the subsequent engine assembly accuracy; therefore, precise measurement of the positional relationships of each component is essential.

[0003] The thrust chamber is a conical thin-walled structure. Locating its central axis requires determining the positions of two points. Therefore, a simple positioning fixture is needed to determine its central axis. Summary of the Invention

[0004] The technical problem solved by the present invention is to overcome the shortcomings of the prior art and provide a positioning fixture for the thrust chamber of a liquid rocket engine, used for aligning the central axis of sheet metal parts and brazed parts such as the thrust chamber of a liquid rocket engine, as well as for scribing and measuring the conical nozzle of the thrust chamber.

[0005] The technical solution of this invention is:

[0006] A liquid rocket engine thrust chamber positioning fixture includes a transmission part and a positioning part; the transmission part includes a chuck, a transmission shaft, and a transmission lead screw; the positioning part includes a positioning claw, a column, a transmission cylinder, a guide sleeve, a positioning disc, and a spring.

[0007] The column is integrally machined, with its lower end inserted into the positioning hole of the worktable and fixed to the worktable via a flange. The upper end is connected to the transmission cylinder, and the contact surface between the column and the worktable is an annular structure. The positioning plate has a petal-shaped structure with several support claws welded to the outside and a flange welded to the inside. The guide sleeve is fitted onto the outer wall of the column, and the annular structure at the bottom of the guide sleeve is bolted to the flange of the positioning plate. The guide sleeve and the positioning plate are supported by springs and can slide up and down along the column. The outer edge of the positioning plate is tapered and is used to contact the inner wall of the thrust chamber, positioning the lower center of the thrust chamber on the center line of the positioning fixture.

[0008] The lead screw is located in the cavity of the column, and the transmission teeth at the lower end of the lead screw mesh with the drive shaft of the worktable; the transmission shaft is located in the cavity of the transmission cylinder, and the lower end of the transmission shaft is inserted into the upper cavity of the lead screw and connected to the upper cavity of the lead screw by a hook key; the upper end of the transmission shaft meshes with the chuck through a spline, and the positioning jaws are installed on the top of the chuck; the positioning jaws can retract or open as the chuck rotates.

[0009] Preferably, 2N sliding columns are evenly arranged around the circumference of the column. One end of the sliding column is fixed to the annular structure of the column, and the other end of the sliding column passes through the annular structure of the guide sleeve. A spring sleeve is designed at the top of the sliding column. The spring is sleeved on the sliding column and is located between the annular structure at the bottom of the guide sleeve and the annular structure of the column, thereby supporting the guide sleeve and the positioning plate to slide up and down along the column. N is 2 or 3.

[0010] Preferably, the chuck includes a slide, a screw spool, a chuck base, a gear spool, a support, a lifting spring, and an adjusting screw;

[0011] The lower end of the support is inserted into the upper cavity of the transmission cylinder, and the two are fixedly connected by bolts. The disc is fixed on the support, and three or six dovetail grooves are opened on the inner side of the upper end of the disc. The dovetail grooves are evenly distributed in the circumference of the disc, and the slide is inserted into the dovetail grooves. The gear disc is inserted into the inner hole of the support, and the adjusting screw is threaded to the bottom of the inner hole of the support. The lower end of the lifting spring is fixed to the adjusting screw, and the upper end contacts the gear disc to support the gear disc. The upper end of the gear disc meshes with the screw through the transmission teeth, and the upper end of the screw meshes with the slide. The internal spline on the gear disc and the external spline on the transmission shaft form a fit, transmitting the rotational motion of the transmission shaft to the chuck.

[0012] Preferably, the meshing surface of the transmission teeth of the toothed disc and the screw disc is an inclined surface.

[0013] Preferably, the upper end of the spool engages with the slide block via teeth formed based on an Archimedean spiral.

[0014] Preferably, the inner wall surface of the upper cavity of the transmission cylinder is a conical surface, and the outer wall surface of the lower end of the support is also a conical surface. The lower end of the support is inserted into the upper cavity of the transmission cylinder, and the two are positioned by the metric conical surface.

[0015] Preferably, the number of positioning claws is three or six, and is equal to the number of slides. The outer radius R is equal to the radius of the thrust chamber throat. The lower end of the positioning claw is connected to the slide on the chuck and opens or retracts together with the slide, thereby achieving positioning of the thrust chamber throat.

[0016] Preferably, the spring's elastic coefficient satisfies the requirement that it can both bear the weight of the positioning plate and the guide sleeve, and also ensure that the lower end face of the thrust chamber contacts the worktable after the thrust chamber is placed on the positioning plate.

[0017] Preferably, the positioning claw is made of cast aluminum.

[0018] A method for using a liquid rocket engine thrust chamber positioning fixture includes:

[0019] During operation, first use the column to position the positioning fixture to the worktable, place the thrust chamber on the positioning fixture, fix the thrust chamber in the appropriate position through the conical outer edge of the positioning plate, and position the lower center of the thrust chamber on the center line of the positioning fixture to complete the first positioning.

[0020] The drive shaft of the worktable meshes with the transmission screw of the positioning fixture. The rotational motion of the drive shaft is transmitted to the positioning fixture through the transmission screw, and then to the drive shaft through the hook key. When the rotational motion of the drive shaft is transmitted to the chuck, it drives the three positioning claws on the chuck to expand or contract uniformly in the radial direction, thereby tightening the throat of the engine thrust chamber and completing the second positioning.

[0021] By locating two points within the thrust chamber, the axis of the thrust chamber can be aligned.

[0022] The present invention has the following beneficial effects:

[0023] (1) This invention achieves the function of aligning the central axis of the thrust chamber by positioning it at two locations: the large end and the throat. In this invention, the transmission screw, driven by the rotational motion of the drive shaft, can transmit motion to the positioning jaws above, resulting in high transmission efficiency and real-time performance. The structure of this invention can be widely used for aligning the central axis of sheet metal parts and brazed parts such as the thrust chamber of liquid rocket engines, as well as for scribing and measuring the conical nozzle of the thrust chamber. It has the advantages of novel structure, convenient use, and strong adaptability.

[0024] (2) This invention utilizes the Archimedes spiral principle to transform the rotational motion of the drive shaft into a constant-speed linear motion of the positioning claws along the radial direction, so that multiple positioning claws can open or retract simultaneously and at the same speed, thereby achieving positioning of the throat of the thrust chamber.

[0025] (3) The present invention can adjust the height of the chuck and positioning claw by adjusting the height of the transmission shaft, transmission screw, transmission cylinder and column; and can adapt to different thrust chamber lower diameters by changing the diameter of the outer circle of the positioning disk. Attached Figure Description

[0026] Figure 1 This is an assembly cross-sectional view of the liquid rocket engine thrust chamber positioning fixture of the present invention;

[0027] Figure 2 This is a schematic diagram of the chuck structure of the present invention;

[0028] Figure 3 This is a half-sectional view of the column of the present invention;

[0029] Figure 4 This is a structural diagram of the external spline of the drive shaft of the present invention;

[0030] Figure 5 This is a front view of the positioning claw of the present invention;

[0031] Figure 6 This is a top view of the positioning claw of the present invention;

[0032] Figure 7 This is a schematic diagram of the Archimedean spiral used in this invention;

[0033] Figure 8 This is a top view of the silk reel of the present invention.

[0034] Figure 9 This is a bottom view of the silk reel of the present invention;

[0035] Figure 10 A view of the silk reel of the present invention from direction A;

[0036] Figure 11 A view of the silk reel of the present invention from direction B;

[0037] Figure 12 This is a half-sectional view of the positioning disk of the present invention;

[0038] Figure 13 This is a top view of the positioning disk of the present invention;

[0039] Figure 14 This is a front view of the tray base of the present invention;

[0040] Among them, 1-positioning claw, 2-chuck, 3-transmission cylinder, 4-transmission shaft, 5-column, 6-hook key, 7-guide sleeve, 8-transmission screw, 9-positioning disc, 10-spring, 11-thrust chamber, 12-worktable; 201-slide, 202-screw spool, 203-disc seat, 204-gear disc, 205-support, 206-lifting spring, 207-adjusting screw, 901-disc, 902-support claw, 903-rib plate. Detailed Implementation

[0041] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0042] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0043] This invention provides a novel, easy-to-use, and highly adaptable positioning fixture for the thrust chamber of a liquid rocket engine.

[0044] like Figure 1 The liquid rocket engine thrust chamber positioning fixture of the present invention includes a transmission part and a positioning part; the transmission part includes a chuck 2, a transmission shaft 4, and a transmission lead screw 8; the positioning part includes a positioning claw 1, a column 5, a transmission cylinder 3, a guide sleeve 7, a positioning disk 9, and a spring 10.

[0045] The lower end of the column 5 is inserted into the positioning hole of the workbench and fixed to the workbench 12 by a flange. The contact surface between the column 5 and the workbench is a ring-shaped structure. The upper end of the column 5 is connected to the transmission cylinder 3, and the transmission cylinder 3 is connected to the support 205 of the chuck 2 to form a support structure.

[0046] The positioning disc 9 has a petal-shaped structure with several supporting claws welded to the outside and a flange welded to the inside. The guide sleeve 7 is fitted onto the outer wall of the column 5. The annular structure at the bottom of the guide sleeve 7 mates with the inner hole of the positioning disc 9 and is connected by bolts. The outer circle of the positioning disc 9 is conical, used to contact the inner wall of the thrust chamber, positioning the lower center of the thrust chamber on the center line of the invention. The guide sleeve 7 and the positioning disc 9 are supported by springs 10 and can slide up and down along the column 5. Specifically, four or six sliding pillars are evenly arranged along the circumference of the column. One end of the sliding pillar is fixed to the annular structure of the column 5, and the other end of the sliding pillar passes through the annular structure of the guide sleeve 7. A spring sleeve is designed at the top of the sliding pillar. The spring 10 is fitted onto the sliding pillar and is located between the annular structure at the bottom of the guide sleeve 7 and the annular structure of the column 5, thereby supporting the guide sleeve 7 and the positioning disc 9 to slide up and down along the column 5.

[0047] The transmission screw 8 is located in the cavity of the column, and the transmission teeth at the lower end of the transmission screw 8 mesh with the drive shaft of the worktable; the transmission shaft 4 is located in the cavity of the transmission cylinder 3, and the lower end of the transmission shaft 4 is inserted into the upper cavity of the transmission screw 8 and connected to the upper cavity of the transmission screw 8 through the hook key 6; the upper end of the transmission shaft 4 meshes with the chuck 2 through the spline, and the positioning claw 1 is installed on the top of the chuck 2; the positioning claw 1 can retract or open as the chuck rotates.

[0048] like Figure 2As shown, the chuck 2 consists of a slide 201, a screw spool 202, a disc base 203, a gear spool 204, a support 205, a lifting spring 206, and an adjusting screw 207. The inner wall of the upper cavity of the transmission cylinder 3 is a conical surface, and the outer wall of the lower end of the support 205 is also a conical surface. The lower end of the support 205 is inserted into the upper cavity of the transmission cylinder 3. The two are positioned by a metric conical surface to ensure their coaxiality and are fixedly connected by bolts. The disc base 203 is fixed on the support 205. The inner side of the upper end of the disc base 203 has three or six dovetail grooves, which are evenly distributed in the circumferential direction of the disc base. The slide 201 is inserted into the dovetail grooves. The gear disc 204 is inserted into the inner hole of the support 205. Its lower end is supported by a lifting spring 206 and an adjusting screw 207 (the adjusting screw 207 is threaded to the bottom of the inner hole of the support 205; the lower end of the lifting spring 206 is fixed to the adjusting screw 207, and its upper end contacts the gear disc 204 to support it). Its upper end meshes with the threaded disc 202 via transmission teeth. The upper end of the threaded disc 202 has teeth formed based on an Archimedean spiral for meshing with the slide block 201. Figure 14 This is the front view of the tray.

[0049] The meshing surface of the transmission teeth of the toothed disc 204 and the screw disc 202 is an inclined surface.

[0050] Figures 8-11 This is a schematic diagram of the wire spool structure of the present invention. The upper end of the wire spool has teeth formed based on the Archimedean spiral, and the lower end has six teeth evenly distributed along the circumference. The two sides of each tooth are 45° and 25° respectively, which is to prevent overload of the transmission teeth when the transmission jams. The upper end of the toothed spool has the same teeth for meshing with the wire spool.

[0051] When the positioning jaws expand or contract to a certain extent and become stuck or self-locked, or when the engagement between the screw spool and the slide block is jammed, the screw spool stops rotating, while the gear spool 204 continues to rotate under the action of the drive shaft. At this time, since the meshing surface between the gear spool and the screw spool is a 45° or 25° inclined plane, the gear spool will compress the lifting spring downward, thereby disengaging the engagement between the gear spool and the screw spool, which can protect the transmission part of the positioning fixture from damage.

[0052] When the drive shaft 4 drives the gear disc 204 to rotate, the gear disc 204 drives the screw disc to rotate through the inclined teeth, and then transmits the rotation to the slide block 201. Under the constraint of the Archimedean spiral teeth, the slide block 201 moves linearly in the radial direction in the dovetail groove of the disc base 203. The dovetail groove of the disc base can cooperate with the slider structure on the slide block.

[0053] The positioning claws are connected to the slide 201 of the chuck, and there are usually three or six of them, which are equal to the number of slides 201. The outer radius R is equal to the radius of the throat of the thrust chamber. When the slide 201 moves, the positioning claws 1 open or retract along the radial direction with the slide.

[0054] The adjusting screw 207 and the lifting spring 206 are used to adjust the tightness of the meshing between the gear disc 204 and the screw spool 202. Tightening the adjusting screw upwards causes the lifting spring 206 to push the gear disc upwards, thus tightening the meshing of the transmission teeth between the gear disc 204 and the screw spool 202; conversely, tightening the adjusting screw downwards loosens the meshing. Furthermore, when the screw spool 202 is subjected to excessive load, the lifting spring 206 can also protect the transmission teeth on the screw spool 202 from damage.

[0055] The guide sleeve 7 is connected to the positioning plate 9 by bolts and supported on the column 5 by spring 10. The whole assembly of the positioning plate 9 and the guide sleeve 7 can slide up and down along the column 5. The purpose of sliding is to avoid over- or under-positioning of the thrust chamber due to improper positioning plate height.

[0056] like Figure 12 and Figure 13 As shown, the positioning disk 9 is welded from a disk 901, a support claw 902, and a rib plate 903. The outer edge of the support claw 902 is designed as a conical surface, as shown in the figure. Figure 12 As shown in the figure, ∠a is greater than 90° and is used to contact the inner wall of the thrust chamber, locate the large end of the thrust chamber, and also bear part of the weight of the thrust chamber.

[0057] The mating surface between the support on the chuck and the transmission cylinder is a metric conical surface to ensure their coaxiality. The transmission shaft 4 and chuck 2 are connected by internal and external splines to utilize the excellent centering properties of the splines and ensure their coaxiality. The elastic coefficient of the spring 10 should be appropriately set, sufficient to support the weight of the positioning plate and guide sleeve, while ensuring that the lower end face of the thrust chamber contacts the worktable after it is placed on the positioning plate. The number of springs is equal to the number of support claws on the positioning plate.

[0058] like Figure 3 The lower end of column 5 is provided with a cylindrical section with high machining precision, and the lower end face of the cylindrical section is provided with a chamfer. The purpose is to position it with the circular hole on the worktable to ensure the coaxiality of column 5 and worktable.

[0059] Motion transmission: The transmission teeth at the lower end of the lead screw 8 mesh with the drive shaft of the worktable, and the upper end is connected to the transmission shaft 4 via the column 5. The upper end of the transmission shaft 4 has an external spline, such as... Figure 4 As shown, it meshes with the internal splines of the gear disc 204 on the chuck 2. The upper end of the gear disc 204 has helical teeth, which mesh with the corresponding teeth on the thread disc 202; the upper end of the thread disc 202 is provided with transmission teeth based on the Archimedean spiral, which mesh with the corresponding teeth on the slide 201. The positioning jaw 1 is connected to the slide 201 on the chuck 2 and moves together with the slide 201.

[0060] like Figure 5 and Figure 6 As shown, the outer radius R of the positioning claw 1 is equal to the radius of the thrust chamber throat, and the positioning claw 1 is an aluminum part, all to reduce the scratches that the positioning claw 1 may cause to the thrust chamber.

[0061] In this invention, the support claw of the positioning disk 9 positions the large end of the thrust chamber, and the positioning claw 1 positions the throat of the thrust chamber, forming two positioning points, both of which are adjustable.

[0062] In operation, the key to the positioning claw 1's ability to open or retract and tighten the throat of the thrust chamber lies in the meshing between the threaded disc 202 on the chuck 2 and the slide 201. The threaded disc 202 has transmission teeth shaped based on the Archimedean spiral, which mesh with corresponding teeth on the slide 201. The Archimedean spiral is also known as a constant velocity curve, such as... Figure 6 As shown, when point P moves at a constant speed along ray OP, this ray rotates around point O at a constant angular velocity. The trajectory of point P is the "Archimedes spiral".

[0063] The polar equation of the Archimedes spiral is:

[0064] ρ=ρ0+aθ

[0065] In the formula: ω is the polar radius, mm; a is the Archimedean spiral coefficient, mm / °, representing the increase in polar radius when point P rotates by 1°; θ is the polar angle, representing the total angle rotated by the Archimedean spiral; ρ0 represents the polar radius when θ = 0°, in mm.

[0066] The rectangular coordinate equation of the above expression can be obtained through trigonometric function transformations.

[0067]

[0068] ρ0 is usually known; by calculating the increase in the polar radius when point P rotates one revolution, the coefficient a can be obtained, thus yielding the complete Archimedean spiral. x and y represent the values ​​of the horizontal and vertical coordinates in a rectangular coordinate system, respectively.

[0069] Figure 7 In the diagram, the thick solid line represents the Archimedean spiral with P0 as the polar radius and θ = 360°. As can be seen from the figure, the increase in polar radius during one revolution is R2 - R1. Therefore, the coefficient... R1 represents the distance between point P and the origin when P is at 0°; R2 represents the distance between point P and the origin after rotating 360°.

[0070] The method of using the liquid rocket engine thrust chamber positioning fixture of the present invention is as follows:

[0071] During operation, the positioning fixture is first positioned on the worktable using the column. The thrust chamber is then placed on the positioning fixture, and the supporting claws of the positioning plate fix the thrust chamber in the appropriate position, completing the first positioning step. The drive shaft of the worktable meshes with the transmission screw of the positioning fixture. The rotational motion of the drive shaft is transmitted to the positioning fixture through the transmission screw, and then to the drive shaft through the hook key. The drive shaft is connected to the chuck via internal and external splines. The chuck has transmission teeth based on the Archimedean spiral. When the rotational motion of the drive shaft is transmitted to the chuck, it can drive the three positioning claws on the chuck to move at a constant speed in the radial direction, thereby tightening the throat of the engine thrust chamber, completing the second positioning step. By positioning the thrust chamber at these two points, the thrust chamber axis is aligned.

[0072] When the positioning tool of this invention is in use, the support is fixed to the transmission cylinder, and the internal spline on the gear disc engages with the external spline on the transmission shaft, transmitting the rotational motion of the transmission shaft to the chuck. The upper end of the gear disc is provided with transmission teeth that can mesh with corresponding teeth on the screw spool, thereby driving the screw spool to rotate. The screw spool is provided with transmission teeth formed based on the Archimedean spiral; when the screw spool rotates, it can drive the slide to move at a constant speed along the radial direction, thereby causing the positioning jaws to open or retract.

[0073] This invention can be widely used in positioning and alignment of sheet metal forming and brazed forming parts, and has the advantages of ingenious structure, convenient use and strong adaptability.

[0074] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0075] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A liquid rocket engine thrust chamber positioning fixture, characterized by: The transmission part comprises a chuck (2), a transmission shaft (4) and a transmission screw rod (8), and the positioning part comprises a positioning claw (1), a column (5), a transmission cylinder (3), a guide sleeve (7), a positioning disc (9) and a spring (10); The column (5) is integrally formed and inserted into the positioning hole of the workbench, and is fixed to the workbench through a flange. The upper end surface of the column (5) is connected to the transmission cylinder (3), and the contact surface between the column (5) and the workbench is in a circular ring structure. The positioning disc (9) is in a petal structure, and a plurality of supporting claws are welded on the outer side of the positioning disc (9), and a flange is welded on the inner side of the positioning disc (9). The guide sleeve (7) is sleeved on the outer wall surface of the column (5), and the bottom end of the guide sleeve (7) is connected to the flange of the positioning disc (9) through a bolt. The guide sleeve (7) and the positioning disc (9) are supported by the spring (10) and can slide up and down along the column (5). The outer edge of the positioning disc (9) is in a conical shape and used for contacting the inner wall surface of the thrust chamber to position the center of the lower end of the thrust chamber on the center line of the positioning clamp. The transmission screw rod (8) is located in the cavity of the column, and the transmission teeth at the lower end of the transmission screw rod (8) are engaged with the driving shaft of the workbench. The transmission shaft (4) is located in the cavity of the transmission cylinder (3), and the lower end of the transmission shaft (4) is inserted into the upper end cavity of the transmission screw rod (8) and connected to the upper end cavity of the transmission screw rod (8) through a hook head key (6). The upper end of the transmission shaft (4) is engaged with the chuck (2) through a spline, and the positioning claw (1) is installed at the top end of the chuck (2). The positioning claw (1) can be retracted or expanded with the rotation of the chuck.

2. A liquid rocket engine thrust chamber positioning fixture according to claim 1, wherein: 2N slide columns are uniformly arranged along the circumference of the column, one end of each slide column is fixed to the circular ring structure of the column (5), the other end of each slide column passes through the circular ring structure of the guide sleeve (7), and a spring sleeve is designed at the top end of each slide column. The spring (10) is sleeved on the slide column and located between the bottom end circular ring structure of the guide sleeve (7) and the circular ring structure of the column (5), so as to support the guide sleeve (7) and the positioning disc (9) to slide up and down along the column (5). N is 2 or 3.

3. A liquid rocket engine thrust chamber positioning fixture as recited in claim 1, characterized by: The chuck (2) comprises a sliding seat (201), a wire disc (202), a disc seat (203), a tooth disc (204), a support (205), a lifting spring (206) and an adjusting screw (207). The lower end of the support (205) is inserted into the upper end cavity of the transmission cylinder (3), and the two are fixedly connected through a bolt. The disc seat (203) is fixed to the support (205), and three or six dovetail grooves are formed in the inner side of the upper end of the disc seat (203). The sliding seat (201) is inserted into the dovetail grooves. The tooth disc (204) is inserted into the inner hole of the support (205), the adjusting screw (207) is threadedly fixed to the bottom of the inner hole of the support (205), the lifting spring (206) is fixed to the adjusting screw (207) at the lower end and in contact with the tooth disc (204) at the upper end, and is used for supporting the tooth disc (204). The upper end of the tooth disc (204) is engaged with the wire disc (202) through transmission teeth, the upper end of the wire disc (202) is engaged with the sliding seat (201), and the inner spline on the tooth disc (204) is matched with the outer spline on the transmission shaft (4) to transmit the rotary motion of the transmission shaft (4) to the chuck (2).

4. A liquid rocket engine thrust chamber positioning fixture according to claim 3, wherein: The driving tooth engagement surface of the tooth disc (204) and the wire disc (202) is an inclined surface.

5. A liquid rocket engine thrust chamber positioning fixture according to claim 4, wherein: The upper end of the wire disc (202) is engaged with the slide (201) through the teeth formed based on the Archimedes spiral.

6. A liquid rocket engine thrust chamber positioning fixture according to claim 4, wherein: The inner wall surface of the cavity at the upper end of the transmission cylinder (3) is a conical surface, and the outer wall surface of the lower end of the support (205) is also a conical surface. The lower end of the support (205) is inserted into the cavity at the upper end of the transmission cylinder (3), and the two are positioned by the conical surfaces.

7. A liquid rocket engine thrust chamber positioning fixture according to claim 4, wherein: The number of the positioning clamping jaws (1) is three or six, which is equal to the number of the slides. The outer radius R is equal to the throat radius of the thrust chamber. The lower end of the positioning clamping jaw (1) is connected with the slide (201) on the chuck (2) and expands or contracts with the slide (201) to realize the positioning of the throat of the thrust chamber.

8. A liquid rocket engine thrust chamber positioning fixture as recited in claim 1, characterized by: The spring (10) has a spring coefficient that can not only bear the weight of the positioning disc (9) and the guide sleeve (7), but also make the lower end surface of the thrust chamber contact the workbench after the thrust chamber is placed on the positioning disc (9).

9. A liquid rocket engine thrust chamber positioning fixture as recited in claim 1, characterized by: The material of the positioning clamping jaw is cast aluminum.

10. A method of using a liquid rocket engine thrust chamber positioning fixture according to any one of claims 1-9, wherein, The method comprises the following steps: During work, the positioning fixture and the workbench are first positioned by the column, the thrust chamber is placed on the positioning fixture, the thrust chamber is fixed in the appropriate position by the conical outer edge of the positioning disc, the center of the lower end of the thrust chamber is positioned on the center line of the positioning fixture, and the first positioning is completed; The drive shaft of the workbench is engaged with the transmission screw rod of the positioning fixture, the rotational movement of the drive shaft is transmitted to the positioning fixture through the transmission screw rod, and then transmitted to the transmission shaft through the hook key. When the rotational movement of the transmission shaft is transmitted to the chuck, the three positioning clamping jaws on the chuck expand or contract uniformly in the radial direction, thereby supporting the throat of the engine thrust chamber, and the second positioning is completed. Through the two positionings of the thrust chamber, the alignment of the axis of the thrust chamber is realized.

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