An inner supporting profiling positioning tool for processing cylindrical cam profile

Abstract

An inner support profiling positioning tool for processing cylindrical cam profile surface, comprising a nut, a conical bushing, a cylindrical cam to be processed, an expansion clamp with cam profile features and a bolt, wherein the expansion clamp is provided with a boss for embedding the conical bushing, the cylindrical cam to be processed is sleeved on the boss, and profiling structure is arranged on the inner surface of the expansion clamp to increase the supporting area as much as possible without interfering with the profile processing tool path, which can ensure that most of the cam features are supported during the entire processing process, and can also avoid local stress too large causing injury; the upper end of the bolt is provided with a thread for screwing with the nut after passing through the conical bushing, and the bottom end of the bolt is provided with a square head matched with the bottom of the expansion clamp, and the expansion clamp expands outward after tightening the nut, so as to clamp the cylindrical cam to be processed in an inner support manner.

Description

Technical Field

[0001] This utility model relates to the field of positioning tooling technology, and in particular to an internal support contour positioning tooling for machining cylindrical cam profiles. Background Technology

[0002] Cylindrical cams are common components in aircraft nose wheel steering systems. They are components with curved profiles created on the end face of a cylinder. Their overall structure is essentially an evolution of a moving cam rolled into a cylinder. They utilize profile fitting to continuously provide a counterforce for centering during turns, assisting the steering system in centering and providing necessary damping. Therefore, the profile of the cylindrical cam is a key feature for controlling turns and centering, and its relative position to the inner bore of the cylindrical cam requires high precision.

[0003] For machining cylindrical cam profiles, the traditional method is to use a three-jaw chuck to grip the inner hole of the cylindrical cam. After the end face of the cylindrical cam is in contact with the plane of the three-jaw chuck, the profile is machined by profile milling using a CNC center. Because the contact area between the jaws of the three-jaw chuck and the inner hole of the cylindrical cam is small, the inner hole of the cylindrical cam is easily damaged when the clamping force is large. In addition, due to the influence of the tool path of the machining profile, the clamping position of the three jaws cannot exceed the lowest point of the cylindrical cam profile. Therefore, during the machining process, most of the cylindrical cam structure is in an unsupported state, which can easily cause machining deformation. Utility Model Content

[0004] The technical problem solved by this utility model is to provide an internal support contour positioning fixture for machining cylindrical cam profiles, so as to solve the problems in the background art mentioned above.

[0005] The technical problem solved by this utility model is achieved by the following technical solution: A conformal positioning fixture for machining cylindrical cam profiles includes a nut, a tapered bushing, a cylindrical cam to be machined, an expansion clamp with cam profile features, and a bolt. The expansion clamp has a boss for inserting the tapered bushing, and the cylindrical cam to be machined is fitted onto the boss. A conformal structure that avoids the cam profile is also provided on the inner surface of the expansion clamp. The upper end of the bolt has a thread for threading through the tapered bushing and connecting with the nut, and the bottom end of the bolt has a square head that mates with the bottom of the expansion clamp. Tightening the nut expands the expansion clamp outwards, clamping the cylindrical cam to be machined in an internally supporting manner.

[0006] In this invention, the expansion sleeve has an inner conical structure, and the conical bushing has the same taper as the inner conical surface of the expansion sleeve to achieve a contact fit.

[0007] In this invention, the bottom of the expansion sleeve is provided with a square groove that mates with the square head, which serves to limit the angle.

[0008] In this invention, the contouring structure provided on the expansion sleeve can increase the support area as much as possible without interfering with the tool path of the surface machining. This ensures that most of the cam features have support during the entire machining process and also avoids pinching damage caused by excessive local stress.

[0009] In this invention, the bottom of the expansion sleeve is configured as a disc structure, and the disc structure has four positioning holes for calibrating the tooling position.

[0010] In this utility model, the expansion sleeve and the conical bushing form a centering expansion and contraction mechanism. The two are engaged by the conical surfaces of the same taper. Tightening the nut drives the conical bushing to move downward and push the expansion sleeve to expand evenly, thereby clamping the inner hole of the cylindrical cam to be processed in an internal support manner.

[0011] Beneficial effects: This utility model utilizes an inner conical expansion sleeve in conjunction with a conical bushing to form a centering expansion and contraction mechanism. The conical bushing evenly pushes the expansion sleeve to expand and clamp the inner hole of the cylindrical cam. At the same time, the expansion sleeve is provided with a contouring structure that avoids the cam profile, so as to maximize the support area without interfering with the tool path of the profile machining. This ensures that most of the cam features have a support body during the entire machining process and avoids excessive local stress that could cause clamping damage. Attached Figure Description

[0012] Figure 1 This is an exploded view of a preferred embodiment of the present invention.

[0013] Figure 2 This is an assembly diagram of a preferred embodiment of the present invention.

[0014] Figure 3 This is a cross-sectional view of a preferred embodiment of the present invention.

[0015] Figure 4 This is a schematic diagram of the expanded jacket in a preferred embodiment of the present invention.

[0016] Figure 5 This is a schematic diagram comparing the effective contact area in a preferred embodiment of the present invention. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the following description, in conjunction with specific illustrations, further elaborates on this utility model.

[0018] See Figures 1-5The illustrated internal support contour positioning fixture for machining cylindrical cam profiles includes a nut 1, a tapered bushing 2, a cylindrical cam 3 to be machined, an expansion clamping sleeve 4 with cam profile features, and a bolt 5. The expansion clamping sleeve 4 has a boss for inserting the tapered bushing 2. The tapered bushing 2 and the internal tapered surface of the expansion clamping sleeve 4 have the same taper to achieve a contact fit. The cylindrical cam 3 to be machined is fitted onto the boss. Simultaneously, a contouring structure 6 that avoids the cam profile is provided on the inner surface of the expansion clamping sleeve 4. The upper end of the bolt 4 has a thread for threading through the tapered bushing 2 and connecting to the nut 1. The bottom end of the bolt 4 has a square head, which engages with a square groove at the bottom of the expansion clamping sleeve 4 to limit the angle. After tightening the nut 1, the expansion clamping sleeve 4 expands outward, clamping the cylindrical cam 3 to be machined in an internal support manner.

[0019] In this embodiment, the expansion sleeve 4 has an inner conical structure.

[0020] In this embodiment, the contouring structure 6 provided on the expansion sleeve 4 can increase the support area as much as possible without interfering with the tool path of the surface machining. This ensures that most of the cam features have support during the entire machining process and also avoids pinching damage caused by excessive local stress.

[0021] In this embodiment, the bottom of the expansion sleeve 4 is configured as a disc structure, and the disc structure has four positioning holes for calibrating the tooling position.

[0022] In this embodiment, the working principle of the internal support contour positioning fixture is as follows: As attached Figure 4 As shown in (a-d), the expansion sleeve 4 and the conical bushing 2 form a centering expansion and contraction mechanism. The two are engaged by conical surfaces with the same taper. In 4a, tightening the nut 1 drives the conical bushing 2 to move downward P and push the expansion sleeve 4 to expand evenly, thereby clamping the inner hole of the cylindrical cam 3 to be processed in an internal support manner. In 4c, the expansion sleeve 4 expands evenly around the perimeter. In 4d, the outer diameter of the expansion sleeve 4 increases and the opening widens. As attached Figure 5 As shown in (a-d), the expansion sleeve 4 is designed with a contouring structure 6 that avoids the cam surface. Through the uniform expansion of the contouring mechanism 6, the effective contact area between the tooling and the inner circular surface of the cam is ensured to be large enough. This not only ensures the stability of the machining process, but also distributes the clamping force evenly to avoid damaging the parts. Among them, 5a represents the expansion sleeve 4, the shaded part Y in 5b is the effective contact area of ​​the existing three-jaw clamping, 5c represents the expansion sleeve 4 fitted with the conical bushing 2, and the shaded part in 5d is the effective contact area of ​​the inner support contouring positioning tooling clamping.

[0023] In this embodiment, the method of using the rapid positioning fixture is as follows: Before use, the tooling position needs to be calibrated accurately, that is, by using the four positioning holes on the expansion sleeve 4 for calibration. Then, the expansion sleeve 4 is fixed on the machine tool. Then, the cylindrical cam 3 to be machined is fitted onto the boss of the expansion sleeve 4 (at this time, the cylindrical cam has not been machined and still has a cylindrical feature). The fit between the bottom surface of the cylindrical cam and the expansion sleeve 4 is checked by micrometer. Then, the nut 1 is tightened, which drives the inner support of the expansion sleeve 4 to clamp the cylindrical cam 3 to be machined. The tool is then calibrated, and the CNC program is called to complete the surface machining. Notice: The expansion sleeve 4 has a large range of expansion and contraction dimensions, which can be compatible with the machining of various types of cylindrical cams with similar profiles and inner holes within the expansion and contraction range. However, if the production cost allows, the best effect is achieved when the outer circle of the expansion sleeve 4 and the inner hole of the cylindrical cam are precisely matched in the free state, which can maximize the contact area during clamping. Due to the self-centering expansion and contraction effect of the expansion sleeve 4, the tooling can be used to correct the poor perpendicularity between the inner hole and the end face of the cylindrical cam 3 to be processed. This tooling has a wide range of applications. When necessary, it can be used in turning. Using the inner hole of the workpiece as a reference, the inner hole can be supported to machine the outer circle, which can also avoid deformation during the machining process without the need for an additional turning mandrel.

[0024] The specific embodiments described herein are merely illustrative examples of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or adopt similar methods to replace them, but without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A conformal positioning fixture for machining a cylindrical cam profile, comprising a nut, a tapered bushing, a cylindrical cam to be machined, an expansion sleeve with cam profile features, and a bolt, characterized in that, The expansion sleeve is provided with a boss for embedding the tapered bushing. The cylindrical cam to be processed is fitted onto the boss. At the same time, a contour structure that avoids the cam profile is provided on the inner surface of the expansion sleeve. The upper end of the bolt is provided with a thread for threading with the nut after passing through the tapered bushing. The bottom end of the bolt is provided with a square head that mates with the bottom of the expansion sleeve.

2. The internal support contour positioning fixture for machining cylindrical cam profiles according to claim 1, characterized in that, The expansion sleeve has an inner conical structure, and the conical bushing has the same taper as the inner conical surface of the expansion sleeve.

3. The internal support contour positioning fixture for machining cylindrical cam profiles according to claim 1, characterized in that, The bottom of the expansion sleeve is provided with a square groove that matches the square head.

4. The internal support contour positioning fixture for machining cylindrical cam profiles according to claim 1, characterized in that, The bottom of the expansion sleeve is designed as a disc structure.

5. The internal support contour positioning fixture for machining cylindrical cam profiles according to claim 4, characterized in that, The disc structure has four positioning holes.

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