Cylindrical gear transmission rod processing fixture and method

Abstract

The application discloses a processing clamp and method for drum gear transmission rod, the processing clamp comprises a clamp base and a ball head positioning pin, the clamp base is provided with a circular blind hole, the inner wall cylindrical surface of the circular blind hole is used as a positioning matching circle, the clamp base is further provided with an angular groove with threads and communicated with the circular blind hole, the axis of the angular groove is perpendicular to the axis of the circular blind hole, and the ball head positioning pin is inserted into the angular groove. When the transmission part of the drum gear transmission rod is processed, the repeated positioning precision is controlled by the gap between the inner wall cylindrical surface of the processing clamp and the outer circle of the gear part, and the angular positioning precision is ensured by controlling the tooth profile precision and the precision of the ball head positioning pin. The application solves the positioning problem that the gear part is firstly processed and then the transmission part working surface is processed, ensures the parallelism of the working surface when the transmission part is processed, and ensures the symmetry requirement of the gear part and the transmission part.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aero-engine manufacturing, and particularly relates to a drum gear transmission rod tooth profile accurate positioning method and a gear automatic centering fixture design. BACKGROUND

[0002] As shown in a drum gear transmission rod shown in Figure 1 and Figure 2 , the drum gear transmission rod mainly consists of a transmission part and a gear part, in order to meet the requirements of aero-engine transmission and working rotation, the position size, symmetry and other requirements between the two parts are very high.

[0003] However, due to the structural characteristics of the part, the part cannot process the transmission part first and then process the gear part, and must be arranged according to the overall process route to process the gear part first and then process the transmission part, which leads to the need to solve the gear positioning technology and the automatic centering fixture of the gear, so as to meet the high symmetry requirements of the transmission part and the gear part, which is the significance of the present application.

[0004] For example, when the above-mentioned drum gear transmission rod is assembled to the hydraulic drive assembly of the engine for transmission power and torque, the transmission site size precision is high, and the parallelism of the two working surfaces of the transmission site is 0.02, and the symmetry of the gear site to the transmission site is 0.08 (the symmetry of the drum gear middle surface to the two working surfaces of the transmission part and the reference C), as shown in Figure 1 and Figure 2 , the part transmission site has a long processing cycle, unstable processing size, and low symmetry qualification rate, which seriously restricts the progress of production and research. SUMMARY

[0005] The present application aims to provide a drum gear transmission rod processing fixture and method, to explore and summarize the gear positioning method and gear automatic centering fixture design of drum gear transmission rod parts, to improve the processing qualification rate and processing efficiency of the drum gear transmission rod, and to lay a foundation for future gear positioning processing of similar parts.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] The processing fixture of the drum gear transmission rod comprises,

[0008] The fixture base is provided with a circular blind hole in the upper end face, the hole wall of the circular blind hole forms a positioning matching surface, the hole bottom surface of the circular blind hole forms a supporting surface, and the circumferential surface of the fixture base is provided with an angular slot with internal threads which is in communication with the circular blind hole, and the axis of the angular slot is perpendicular to the axis of the circular blind hole;

[0009] A ball head positioning pin is inserted into an angular slot, and a ball head portion of the ball head positioning pin points into a circular blind hole.

[0010] The machining fixture for the drum gear transmission rod further comprises a filler which is tightly attached to the surface of the ball head portion of the ball head positioning pin.

[0011] The machining method of the drum gear transmission rod comprises a transmission portion and a gear portion, and the gear portion has been machined before the machining of the transmission portion, there is a parallelism requirement between two working surfaces to be machined on the transmission portion, there is a machined cylindrical surface reference on the transmission portion, the gear portion has a symmetry requirement to the cylindrical surface reference of the transmission portion and the symmetry center surface of the two parallel working surfaces, the positioning step is included when machining the two parallel working surfaces of the transmission portion, and the machining fixture of claim 1 is used in the positioning step, specifically comprising:

[0012] Step 1: the end surface of the gear portion is inserted into the circular blind hole and attached to the bottom surface of the circular blind hole, and the ball head portion of the ball head positioning pin is attached to the tooth profile of the gear portion after being inserted through the angular slot;

[0013] Step 2: the repeated positioning accuracy of the gear portion is ensured by controlling the cooperation gap between the outer circle of the gear portion and the cylindrical surface of the hole wall of the circular blind hole in the fixture base, and the angular positioning accuracy of the gear portion is ensured by controlling the tooth profile accuracy of the gear portion and the cooperation accuracy of the ball head positioning pin.

[0014] As an option, in step 1, the fixture base is installed on the numerical control milling machine, the positioning matching surface and the supporting surface of the fixture base are aligned to ensure that the positioning matching surface and the supporting surface have a jump value within a preset range, then the fixture base is fixed on the numerical control milling machine, and the outer circle jump value of the positioning circle of the fixture base and the straightening jump value of the angular slot are aligned before machining.

[0015] As an option, in step 2, the ball head positioning pin is rotated and tightened along the middle surface of the drum gear of the gear portion to stop the drum gear profile, so that the ball head positioning pin is attached to the drum gear.

[0016] The ball head positioning pin and the drum gear are filled with copper sheets as fillers.

[0017] Further, the machining method of the drum gear transmission rod further comprises step 3: the drum gear transmission rod is pressed tightly, the machining reference jump value of the transmission portion is aligned, and the two parallel working surfaces of the transmission portion are milled.

[0018] The drum gear transmission rod tooth shape accurate positioning method and the automatic centering fixture of the gear solve the processing problem of the drum gear transmission rod, and can realize the processing of the part with quality and quantity at a high speed, and on the basis of the research, the processing technology of the drum gear transmission rod is finally promoted to the field of gear positioning.

[0019] Compared with the prior art, the drum gear transmission rod tooth shape accurate positioning method and the automatic centering fixture of the gear solve the processing problem of the drum gear transmission rod, and can realize the processing of the part with quality and quantity at a high speed, and on the basis of the research, the processing technology of the drum gear transmission rod is finally promoted to the field of gear positioning. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram for finish milling of a working surface of a drum gear transmission rod;

[0021] Figure 2 is a top view of Figure 1 ;

[0022] Figure 3 is a schematic diagram for positioning of a drum gear transmission rod;

[0023] In the figure, 1 is a fixture base; and 2 is a ball head positioning pin. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with the drawings and specific embodiments, but should not be understood as the scope of the subject matter described herein being limited to the following embodiments, and any modifications, replacements and changes made according to the ordinary technical knowledge and common practices in the art without departing from the above technical idea of the present application are included in the scope of the present application.

[0025] As shown in Figures 1-2 , it is a drum gear transmission rod to be processed according to the present application. Figure 2 The first tooth marked in the figure is convenient for measurement personnel to understand when measuring, and indicates that the tooth shape to be measured needs to be measured on the index circle. Figure 2 In the figure, the reference B refers to the center of symmetry of the two parallel working surfaces, the reference D refers to one side plane, and the reference C refers to a machined cylindrical surface on the transmission part.

[0026] The present application mainly includes two aspects of the exploration and establishment of the drum gear positioning method and the design of the automatic centering fixture of the gear.

[0027] Exploration and establishment of the drum gear positioning method:

[0028] Achieving gear positioning primarily requires ensuring the accuracy of both the gear and the fixture. Therefore, each component in the fixture system must be precisely positioned to ensure that each component can be installed in the same position every time it is used. The principle of this invention is to ensure repeatability by controlling the fit clearance between the outer circle of the gear and the cylindrical surface (positioning circle) containing the circular blind hole wall of the fixture; and to ensure angular positioning accuracy by controlling the accuracy of the gear teeth and the angular pins in the fixture.

[0029] The process of positioning the drum-shaped tooth profile is as follows:

[0030] 1) Design and manufacture a clamp base 1 that mates with the top of the drum-shaped tooth. The clamp base 1 is as follows: Figure 3 As shown, when the gear part is placed into the circular blind hole of the fixture base 1, a clearance of 0.02 is reserved on one side (that is, before the ball head locating pin 2 is tightened against the gear part, there is a clearance of 0.02 between the cylindrical inner wall of the circular blind hole of the fixture base 1 and the outer circle of the gear part at any position). The fixture base 1 is installed on the machining center. Before machining, the outer circle (locating circle) of the fixture base 1 is aligned (centered) at 0.005, and the angular groove straightening runout is 0.01 (straightening refers to aligning the angular locating surface of the fixture before machining, which is in the same direction as the ball head locating pin 2).

[0031] 2) Along the midpoint of the drum-shaped tooth, use a φ4.85 ball-end locating pin 2 with an M4 rating to rotate and press against the contour of the drum-shaped tooth with a tightening torque of approximately 0.5 kgfm, so that the ball-end locating pin 2 fits against the drum-shaped tooth. Figure 3 As shown; and fill the space between the ball head locating pin 2 and the gear surface with suitable copper foil to hold the part in place;

[0032] 3) Press the part firmly (at this time, the end face of the gear part of the part should be in close contact with the bottom surface of the circular blind hole of the fixture base 1, using...). Figure 1 The three points indicated by the middle arrow are clamped, two with pressure plates and one with a ball-head locating pin 2). The outer circle runout of the cylindrical surface reference C of the part is 0.005. The program is adjusted, and the milling of the two parallel working surfaces of the subsequent transmission part is carried out.

[0033] This invention establishes a machining method for the drum-shaped gear transmission rod. First, the CNC milling parameters and corresponding fixture parameters are set according to the structural dimensions of the part. A fixture base 1 that mates with the top of the drum-shaped gear is designed and manufactured. A 0.02mm gap is reserved on one side between the outer circle of the gear part and the cylindrical hole wall of the circular blind hole of the fixture base 1 at any position.

[0034] Machining and assembly of the fixture: The fixture is machined into individual parts such as fixture base 1, ball head locating pin 2, pressure plate, and nut. Each individual part is then manufactured according to the design dimensions. The mating surfaces of each individual part should be machined to ensure accurate positioning and connection of the fixture. The pressure plate is then assembled onto the fixture base 1.

[0035] Part processing preparation: install the fixture on the numerical control milling machine, align the fixture positioning surface and support surface, ensure that the surface runout is 0.01 max, and fix it on the numerical control milling machine. Before processing, align the outer circle runout of the fixture base 1 to be within 0.005, and the angular groove straightness to be within 0.01.

[0036] Along the middle surface of the gear, use a φ4.85 ball head positioning pin 2 with M4 to rotate against the gear profile with a tightening torque of about 0.5Kgfm, so that the ball head positioning pin 2 fits the gear, as shown in Figure 2 .

[0037] Press the part tightly, the pressing method is shown in Figure 1 three arrow positions, including two vertical direction pressing and one horizontal direction pressing, align the reference C outer circle runout to be within 0.005 (after the ball head positioning pin 2 presses the gear, the part will be offset by about 0.02 relative to the center, so before processing, the reference C must be aligned within 0.005 to correct the eccentricity and ensure that the processing program center point will not change).

[0038] After the above method is used for part processing, the precision milling processing efficiency of the gear transmission rod is improved by 2-4 times compared with before, and the part can achieve 100% processing qualification.

[0039] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art. Although the above describes the specific embodiments of the present application for the purpose of understanding the present application by those skilled in the art, it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and limited by the appended claims, and all the inventions utilizing the concept of the present application are included in the protection.

Claims

1. A method for machining a drum-shaped gear transmission rod, wherein the drum-shaped gear transmission rod includes a transmission part and a gear part, and the gear part is machined before the transmission part is machined; there is a parallelism requirement between the two working surfaces to be machined on the transmission part; there is a pre-machined cylindrical surface reference on the transmission part; and the gear part has symmetry requirements with respect to the cylindrical surface reference of the transmission part and the symmetry center plane of the two parallel working surfaces, characterized in that: The machining fixtures used include, The fixture base (1) has a circular blind hole on its upper end face. The cylindrical surface where the hole wall of the circular blind hole is located forms a positioning mating surface, and the bottom surface of the circular blind hole forms a support surface. The circumferential surface of the fixture base (1) has an internally threaded angular groove that communicates with the circular blind hole. The axis of the angular groove intersects perpendicularly with the axis of the circular blind hole. Ball-head locating pin (2), the ball-head locating pin (2) is inserted into the angular groove, and the ball head part of the ball-head locating pin (2) points into the circular blind hole; The machining of the two parallel working surfaces of the transmission part includes a positioning step, and the positioning step uses the aforementioned machining fixture, specifically: Step 1: Insert the end face of the gear part into the circular blind hole and fit it against the bottom surface of the circular blind hole. After the ball head positioning pin (2) is inserted through the angular groove, the ball head part fits against the tooth profile of the gear part. Install the fixture base (1) on the CNC milling machine and align the positioning mating surface and support surface of the fixture base (1) to ensure that the runout value of the positioning mating surface and support surface is within the preset range. Then fix the fixture base (1) on the CNC milling machine. Before processing, align the fixture base (1) as the runout value of the outer circle of the positioning circle and the straightening runout value of the angular groove. Step 2: The repeatability of the gear part is ensured by controlling the fit clearance between the outer circle of the gear part and the cylindrical surface of the circular blind hole wall in the fixture base (1); the angular positioning accuracy of the gear part is ensured by controlling the tooth profile accuracy of the gear part and the fit accuracy of the ball head positioning pin (2); along the split surface of the drum-shaped tooth of the gear part, the ball head positioning pin (2) is rotated and tightened to press against the outline of the drum-shaped tooth, so that the ball head positioning pin (2) fits against the drum-shaped tooth. Step 3: Press the drum-shaped gear transmission rod tightly, align the machining reference runout value of the transmission part, and mill the two parallel working surfaces of the transmission part.

2. The machining method of the drum-shaped gear transmission rod according to claim 1, characterized in that: The space between the ball-head locating pin (2) and the drum-shaped tooth is filled with a copper sheet as a filler.

3. The machining method of the drum-shaped gear transmission rod according to claim 1, characterized in that: The machining fixture also includes a filler material that is in close contact with the ball head portion surface of the ball head locating pin (2).

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