An outer circle grinding tool and method for thin-walled web sealing bushing

Abstract

The application discloses a kind of thin-walled web's sealing bush outer circle grinding frock and method, frock includes base, body, sleeve, threaded bush, gasket, plug, filling ring, first pressing plate, connecting shaft, second pressing plate, multiple fixed bolts, compression nut and plunger, wherein sleeve realizes radial outer inflation by liquid plastic in body, and the inner hole of sealing bush of thin-walled web is inflated tightly.Filling ring is inserted into the web face cavity of sealing bush of thin-walled web, and then first pressing plate, second pressing plate and compression nut are cooperated to realize the tightening clamping of part.Before grinding, inner hole is inflated tightly by moving plunger, and is installed on outer circle grinding machine by connecting shaft and the top hole on the end face of base.The application has high clamping precision, overcomes the deformation problem of web during grinding process, and improves the one-time machining qualification rate of outer circle grinding of sealing bush under the premise of meeting technical condition requirements.

Description

Technical Field

[0001] This invention belongs to the field of machining technology for sealing bushings in aero engines, specifically relating to machining methods and tooling for sealing bushings. Background Technology

[0002] Currently, there are many types of sealing bushings used in the structural design of aero-engine fan components. The technical requirements for the outer diameter of these sealing bushings are extremely high. In operation, the outer diameter of this type of sealing bushing mates with the high-speed rotating inner surface of graphite to provide a seal. The outer diameter of this type of sealing bushing is the outer part of a thin-walled web structure, and the technical requirements for its machining are a cylindricity of 0.005 mm and an outer diameter tolerance of 0.01 mm.

[0003] During machining, the outer diameter needs to be machined on a chrome-plated surface, so grinding is used. Due to the special structure of the thin-walled web and the overall structural characteristics of the part, which restrict the tooling design, the outer diameter of the part deforms under the grinding pressure of the grinding wheel during machining, resulting in taper after machining. Ultimately, this causes the cylindricity and outer diameter tolerances of the part to be unqualified.

[0004] Currently, this type of sealing bushing is processed by leaving a margin and then making secondary adjustments based on the amount of deformation, as well as re-chrome plating for repair. However, the first-pass yield of this processing method is only 30%, which not only affects the product delivery schedule, but also makes it difficult to meet the requirements in terms of processing cost and processing quality.

[0005] For the reasons mentioned above, it is necessary to design a tooling and method that can improve the first-pass yield of such sealing bushings. Summary of the Invention

[0006] This invention aims to provide a tooling and method for grinding the outer diameter of a sealing bushing with a thin-walled web, solving the problems of deformation during the machining of the thin-walled web structure of the sealing bushing and the difficulties in fixture design caused by its special structure, thereby improving the clamping accuracy of the sealing bushing of the thin-walled web, overcoming the deformation problem encountered during the machining process, and ultimately improving the first-pass yield of the outer diameter grinding of the sealing bushing while meeting the technical requirements.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A grinding fixture for the outer cylindrical portion of a thin-walled web sealing bushing includes:

[0009] The body, the interior of which contains a liquid plastic cavity for filling with liquid plastic;

[0010] The base is assembled at the first axial end of the body, and the base is coaxial with the body and a first center hole is machined on the axial end face of the base away from the body.

[0011] A plunger, which is mounted on the body and has one end extending into the liquid-plastic cavity;

[0012] A sleeve is fitted onto the circumferential surface of the body, and the sleeve is disposed at the outlet of the corresponding liquid plastic cavity;

[0013] A connecting shaft is detachably connected to the second axial end of the main body. The connecting shaft is coaxial with the main body and has a second center hole machined on the axial end face away from the main body.

[0014] A filling ring, the shape of which is consistent with the contour of the cavity of the sealing bushing of the thin-walled web and fills the cavity of the cavity of the sealing bushing of the thin-walled web. The filling ring is made of rubber and is arranged at the second axial end of the body.

[0015] The first pressure plate is detachably connected to the second axial end of the body via a connector, and the axial end face of the first pressure plate is used to press the sealing bushing of the thin-walled web.

[0016] The second pressure plate is sleeved on the connecting shaft, and the axial end face of the second pressure plate is used to press the filling ring;

[0017] A clamping nut is threaded onto the connecting shaft and clamps the second pressure plate.

[0018] Furthermore, a stepped hole is formed on the circumferential outer surface of the body, which communicates with the liquid plastic cavity. A threaded bushing is installed in the stepped hole. After the plunger passes through the threaded bushing, one end extends into the liquid plastic cavity, and the other end is connected to the first fixing bolt placed in the threaded bushing.

[0019] Furthermore, the liquid plastic cavity includes a first cavity extending along the axial direction of the body and a second cavity extending along the radial direction of the body. The first cavity and the second cavity are connected and filled with liquid plastic. One end of the plunger is located in the first cavity, and a sleeve is correspondingly provided at the outlet of the second cavity.

[0020] Furthermore, a plug is provided at the entrance of the first cavity, and the plug is located between the base and the first axial end of the body and seals the liquid plastic in the first cavity with a mating gasket.

[0021] Furthermore, the outer dimensions of the filling ring are such that a gap is left between it and the inner wall of the cavity of the sealing bushing of the thin-walled web.

[0022] Furthermore, the filling ring is made of fluororubber.

[0023] As one solution:

[0024] The sleeve is detachably connected to the body by second fixing bolts evenly distributed along the outer circumferential surface of the body.

[0025] The connecting shaft is detachably connected to the second axial end of the body via a third fixing bolt;

[0026] The first pressure plate is detachably connected to the second axial end of the body via the fourth fixing bolt.

[0027] As one embodiment, the base is detachably assembled to the first axial end of the body via a fifth fixing bolt for connection and a sixth fixing bolt for angular positioning.

[0028] A method for grinding the outer diameter of a sealing bushing with a thin-walled web, using the aforementioned grinding fixture for the outer diameter of a sealing bushing with a thin-walled web, and including the following steps:

[0029] Step 1: Before grinding, clamp the inner hole of the sealing bushing of the thin-walled web plate onto the outer surface of the sleeve.

[0030] Step 2: Use the first pressure plate and connectors to press the axial end face of the sealing bushing of the thin-walled web plate;

[0031] Step 3: Place the filling ring into the cavity of the web surface of the sealing bushing of the thin-walled web, and then press the filling ring tightly with the second pressure plate.

[0032] Step 4: Rotate the clamping nut on the connecting shaft to tighten the second pressure plate;

[0033] Step 5: Move the plunger towards the interior of the body to squeeze the liquid plastic in the liquid plastic cavity. Use the liquid plastic to push the sleeve to generate radial displacement, thereby tightening the inner hole of the sealing bushing of the thin-walled web.

[0034] Step Six: Using the first and second centers, place the external cylindrical grinding fixture with the thin-walled web sealing bushing clamped into the external cylindrical grinding machine to grind the outer cylindrical surface of the thin-walled web sealing bushing.

[0035] Furthermore, in step one, the outer circular surface of the sleeve and the inner hole of the sealing bushing of the thin-walled web are interference fit.

[0036] Compared with the prior art, the present invention has the following characteristics:

[0037] (1) A liquid plastic tensioning fixture was designed for the inner hole of the sealing bushing of the thin-walled web. This design improves the positioning accuracy of the inner hole of the part. At the same time, the reasonable interference parameters are designed to ensure that the liquid plastic tensioning surface can eliminate the gap between the inner hole surface of the part and the fixture when the part is clamped, and the part will not deform due to excessive interference after tensioning.

[0038] (2) When designing the clamping scheme between the cavities of the thin-walled web, a filler ring is added to address the deformation of the web during grinding. The contour of the filler ring matches the contour of the cavity on the web surface. As a filler material, the filler ring can be fixed by the clamping structure of the tooling during clamping, eliminating the risk of it detaching from the fixture during grinding rotation. The rubber material (e.g., fluororubber) used for the filler ring has a certain degree of ductility, allowing it to fit snugly against the inner contour of the web surface cavity during use. Simultaneously, this rubber material also possesses a certain strength when compressed, maintaining its shape after compression. In the dimensional design, a 0.20mm gap is left between the filler ring and the inner wall of the cavity on the web surface of the part, preventing interference between the filler ring and the inner cavity of the web during clamping, which could lead to deformation of the web.

[0039] (3) The sealing bushing of the thin-walled web adopts a double-pressure plate structure design for support and clamping. One pressure plate is designed for the support and clamping end face of the sealing bushing. The filling ring on the web surface is clamped by another pressure plate. This design allows for the use of a larger tightening force to tighten the bolts, ensuring the pressure plates clamp the support and clamping end faces of the parts and preventing the parts from loosening. When clamping the filling ring, a smaller tightening force is used to clamp the pressure plate, avoiding excessive clamping force that could deform the filling ring.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] (1) A design scheme using liquid plastic tensioning and an interference parameter of 0.05mm (i.e., the interference fit between the outer diameter of sleeve 3 and the inner hole of the part is 0.05mm) is used to realize the clamping application of this type of positioning method on the part. This satisfies the purpose of eliminating the gap between the parts during positioning and also solves the negative effects caused by excessive tensioning force. At the same time, the inner hole of the part has a stepped surface. The 0.05mm tensioning parameter design will not damage the contact surface between the tensioning structure and the part at the transition of the inner hole stepped surface, so that the tooling can be used for the positioning of the part. The tensioning positioning accuracy is better than the traditional mandrel positioning design. Traditional mandrel positioning, due to its fixed size, can only be designed as a coarse positioning design with a gap between the mandrel and the inner hole of the part. Such a design requires the operator to repeatedly align the rotation center of the part before processing, and the part is prone to slippage during processing, resulting in poor stability. The liquid plastic tensioning structure, by limiting the interference, ensures that the part does not need to be aligned during the clamping process, and also improves the positioning accuracy and rigidity of the part, thereby improving the first-pass yield and efficiency of the part.

[0042] (2) The traditional method to prevent deformation is to fill the cavity on the web surface with a low-melting-point metal (such as...). Figure 2Low-melting-point metals expand upon cooling, causing the web surface to warp upwards during extrusion. After the low-melting-point metal is dissolved during processing, the web surface shifts downwards, resulting in runout and a false impression of acceptable machining before the filler was dissolved, affecting the part's cylindricity. This invention uses a rubber filler ring, simplifying clamping. The double-plate design simply requires placing the filler into the web cavity and then pressing the plates together. This solution eliminates the tedious steps of dissolving, filling, and re-dissolving. Furthermore, the gap between the filler ring and the web surface ensures rigidity during assembly and prevents web deformation caused by overfilling.

[0043] (3) The tooling of the present invention improves the clamping accuracy, solves the problem of web deformation of the part, simplifies the clamping process, and improves the processing efficiency of the part by 80% in actual application. The first-time processing qualification rate is increased from 30% to 100%, which solves the problems of secondary finishing and chromium removal and chromium plating reprocessing in the current processing method, and ensures that the cylindricity and outer diameter tolerance are qualified. Attached Figure Description

[0044] Figure 1 This is a schematic diagram showing the grinding requirements of the outer diameter of the sealing bushing, which is a component in this invention.

[0045] Figure 2 This is a schematic diagram of a traditional clamping method;

[0046] Figure 3 This is a schematic diagram of the clamping of the tooling of the present invention;

[0047] Figure 4 This is a schematic diagram of the tooling for the present invention;

[0048] Figure 5 for Figure 4 The left view;

[0049] Figure 6 A three-dimensional model of the sealing bushing;

[0050] In the diagram: 1-base, 2-body, 3-sleeve, 4-threaded bushing, 5-gasket, 6-plug, 7-filler ring, 8-first pressure plate, 9-connecting shaft, 10-second pressure plate, 11-first fixing bolt, 12-compression nut, 13-second fixing bolt, 14-third fixing bolt, 15-fourth fixing bolt, 16-fifth fixing bolt, 17-sixth fixing bolt, 18-plunger. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0052] like Figure 1 and Figure 6 As shown, this is a sealing bushing for the thin-walled web plate to be ground according to the present invention. The bolded lines in the figure represent the outer cylindrical surface to be machined. The figure also shows the technical requirements for the cylindricity of this outer cylindrical surface: 0.005 mm and an outer diameter tolerance of 0.01 mm. Inside this outer cylindrical surface is a ring of sealing bushing web plate cavity and a stepped inner hole.

[0053] like Figure 2 As shown, before traditional cylindrical grinding, a low-melting-point metal is filled into the cavity of the web surface of the sealing bushing.

[0054] like Figures 3-5 The image shows a grinding fixture for the outer cylindrical sealing bushing of a thin-walled web, designed according to the present invention. This fixture mainly consists of a base 1, a body 2, a sleeve 3, a threaded bushing 4, a gasket 5, a plug 6, a filling ring 7, a first pressure plate 8, a connecting shaft 9, a second pressure plate 10, a first fixing bolt 11, a clamping nut 12, a second fixing bolt 13, a third fixing bolt 14, a fourth fixing bolt 15, a fifth fixing bolt 16, a sixth fixing bolt 17, and a plunger 18.

[0055] Body 2 is a rotating body, serving as the main structure of the entire tooling. Its interior contains a liquid plastic cavity for filling with liquid plastic, such as... Figure 3 As shown, the liquid plastic cavity includes an axial portion and a radial portion along the body 2. One end of the axial portion serves as the inlet for filling the liquid plastic and is sealed with a plug 6 and a gasket 5. The radial portion communicates with the axial portion, and a sleeve 3 is designed at the outlet of the radial portion. The sleeve 3 is mounted on the circumferential surface of the body 2 by six second fixing bolts 13. Figure 4 As shown, the interference fit between sleeve 3 and body 2 is no greater than 0.05mm. The inner wall of sleeve 3 undergoes radial deformation under the force of the liquid plastic in the radial portion, thereby achieving the tightening of the inner hole of the sealing bushing of the thin-walled web. The design scheme of the liquid plastic tooling is prior art, therefore it will not be described in detail in this embodiment.

[0056] The base 1 and the connecting shaft 9 are respectively assembled on the two axial end faces of the body 2, and each axial end face is machined with a center hole. The connecting shaft 9 is connected to the body 2 by the third fixing bolt 14, while the base 1 is fixedly connected by the fifth fixing bolt 16 (for fixing) and the sixth fixing bolt 17 (for positioning the base 1 relative to the body 2 at an angle, such as...). Figure 4 and Figure 5 The base 1 has two planes parallel to the axis of the body 2 on its outer surface. The angular positions of these two planes relative to the body 2 are determined by the sixth fixing bolt 17. The base 1 is mounted on the body 2. Figure 5 .

[0057] A stepped hole is formed on the circumferential surface of the body 2, and the end of the stepped hole communicates with the axial portion of the liquid-plastic cavity. The plunger 18 is inserted into the stepped hole and extends into the axial portion of the liquid-plastic cavity. The clearance between the circumferential surface of the plunger 18 and the stepped hole is no greater than 0.01 mm (see...). Figure 5 This serves as a seal. A threaded bushing 4 is also installed inside the stepped hole, and a first fixing bolt 11 is installed inside the threaded bushing 4. The end of the first fixing bolt 11 is connected to the plunger 18.

[0058] The filling ring 7 is made of fluororubber, and its outline is consistent with the cavity of the web surface, with gaps left, such as... Figure 4 The bolded line indicates the gap between the outer surface of the filling ring 7 and the inner wall of the cavity of the sealing bushing. At this position, the outer diameter of the filling ring 7 leaves a distance of 0.2 mm between its outer surface and the inner wall of the cavity of the sealing bushing. This distance can prevent the inner wall of the cavity of the sealing bushing from deforming due to compression after the filling ring 7 is pressed against it.

[0059] The first pressure plate 8 and the second pressure plate 10 are assembled together with the connecting shaft 9 on the same side of the body 2. The first pressure plate 8 is connected to the body 2 by the fourth fixing bolt 15, and the second pressure plate 10 is pressed against the end face of the filling ring 7 by the clamping nut 12. The clamping nut 12 is installed through the external thread on the surface of the connecting shaft 9.

[0060] When using the tooling of the present invention to grind the outer cylindrical surface of the sealing bushing of a thin-walled web, the following steps shall be performed:

[0061] 1. When clamping, fit the inner hole of the sealing bushing of the thin-walled web plate onto the outer circular surface of the sleeve 3;

[0062] 2. Press the end face of the sealing bushing of the thin-walled web plate with the first pressure plate 8, and then tighten the fourth fixing bolt 15 to press it tight;

[0063] 3. Place the filling ring 7 into the cavity of the web surface, and then install the second pressure plate 10;

[0064] 4. Tighten the clamping nut 12 on the connecting shaft 9 until the second pressure plate 10 presses the filling ring 7;

[0065] 5. Rotate the first fixing bolt 11 to move the plunger 18 into the body 2, thereby squeezing the liquid plastic. The liquid plastic then applies force to the inner wall of the sleeve 3, causing the sleeve 3 to deform radially, thereby tightening the inner hole of the sealing bushing of the thin-walled web and eliminating the gap between it and the inner hole (the outer circle of the sleeve 3 and the inner hole of the part are interference fit of 0.05mm).

[0066] 6. Place the base 1 and the two center holes on the connecting shaft 9 into the cylindrical grinding machine and begin grinding.

[0067] The outer cylindrical surface of the sealing bushing with thin-walled web, ground according to the above steps, can meet the requirements of 0.005 mm cylindricity and 0.01 mm outer diameter tolerance.

[0068] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A grinding fixture for the outer cylindrical portion of a sealing bushing in a thin-walled web, characterized in that, include: Body (2), the body (2) contains a liquid plastic cavity for filling liquid plastic; The base (1) is mounted on the first axial end of the body (2). The base (1) is coaxial with the body (2) and the axial end face of the base (1) away from the body (2) is machined with a first tip hole. A plunger (18) is mounted on the body (2), with one end of the plunger (18) extending into the liquid-plastic cavity; Sleeve (3), the sleeve (3) is fitted onto the circumferential surface of the body (2), and the sleeve (3) is set at the outlet of the corresponding liquid plastic cavity; A connecting shaft (9) is detachably connected to the second axial end of the body (2). The connecting shaft (9) is coaxial with the body (2) and a second center hole is machined on the axial end face of the connecting shaft (9) away from the body (2). The filling ring (7) has the same shape as the cavity outline of the sealing bushing of the thin-walled web and fills the cavity of the sealing bushing of the thin-walled web. The filling ring (7) is made of rubber and is arranged at the second axial end of the body (2). The first pressure plate (8) is detachably connected to the second axial end of the body (2) via a connector. The axial end face of the first pressure plate (8) is used to press the sealing bushing of the thin-walled web. The second pressure plate (10) is sleeved on the connecting shaft (9), and the axial end face of the second pressure plate (10) is used to press the filling ring (7). A clamping nut (12) is threaded onto the connecting shaft (9) and clamps the second pressure plate (10). The outer circumferential surface of the body (2) has a stepped hole, which is connected to the liquid plastic cavity. A threaded bushing (4) is installed in the stepped hole. After the plunger (18) passes through the threaded bushing (4), one end of it extends into the liquid plastic cavity, and the other end is connected to the first fixing bolt (11) placed in the threaded bushing (4). The liquid plastic cavity includes a first cavity extending along the axial direction of the body (2) and a second cavity extending radially along the body (2). The first cavity and the second cavity are connected and filled with liquid plastic. One end of the plunger (18) is located in the first cavity, and a sleeve (3) is correspondingly provided at the outlet of the second cavity.

2. The grinding fixture for the outer cylindrical portion of a thin-walled web sealing bushing according to claim 1, characterized in that: A plug (6) is provided at the entrance of the first cavity, and the plug (6) is located between the base (1) and the first axial end of the body (2) and seals the liquid plastic in the first cavity through a mating gasket (5).

3. The grinding fixture for the outer cylindrical portion of a thin-walled web sealing bushing according to claim 1, characterized in that: The outer dimensions of the filling ring (7) are such that there is a gap between it and the inner wall of the cavity of the web surface of the sealing bushing of the thin-walled web.

4. The grinding fixture for the outer cylindrical portion of a thin-walled web sealing bushing according to claim 1, characterized in that: The filling ring (7) is made of fluororubber.

5. The grinding fixture for the outer cylindrical portion of a thin-walled web sealing bushing according to claim 1, characterized in that: The sleeve (3) is detachably connected to the body (2) by second fixing bolts (13) evenly distributed along the outer circumferential surface of the body (2); The connecting shaft (9) is detachably connected to the second axial end of the body (2) by a third fixing bolt (14); The first pressure plate (8) is detachably connected to the second axial end of the body (2) by the fourth fixing bolt (15).

6. The grinding fixture for the outer cylindrical sealing bushing of a thin-walled web according to claim 1, characterized in that: The base (1) is detachably assembled to the first axial end of the body (2) by means of a fifth fixing bolt (16) for connection and a sixth fixing bolt (17) for angular positioning.

7. A method for grinding the outer cylindrical portion of a sealing bushing with a thin-walled web, characterized in that, The tooling for grinding the outer cylindrical portion of the sealing bushing of the thin-walled web as described in claim 1 includes the following steps: Step 1: Before grinding, clamp the inner hole of the sealing bushing of the thin-walled web plate onto the outer surface of the sleeve (3); Step 2: Use the first pressure plate (8) and connecting parts to press the axial end face of the sealing bushing of the thin-walled web plate; Step 3: Place the filling ring (7) into the cavity of the web surface of the sealing bushing of the thin-walled web, and then press the filling ring (7) tightly through the second pressure plate (10). Step 4: Rotate the clamping nut (12) on the connecting shaft (9) to clamp the second pressure plate (10); Step 5: Move the plunger (18) towards the inside of the body (2) to squeeze the liquid plastic in the liquid plastic cavity, and use the liquid plastic to push the sleeve (3) to generate radial displacement, thereby tightening the inner hole of the sealing bushing of the thin-walled web. Step Six: Using the first and second centers, place the external cylindrical grinding fixture with the thin-walled web sealing bushing clamped into the external cylindrical grinding machine to grind the outer cylindrical surface of the thin-walled web sealing bushing.

8. The method for grinding the outer cylindrical portion of a sealing bushing for a thin-walled web according to claim 7, characterized in that: In step one, the outer circular surface of the sleeve (3) and the inner hole of the sealing bushing of the thin-walled web are interference fit.

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