Design method of large suspension depth and small diameter duplex gear pinion gear grinding tool bar

Abstract

The present application belongs to the technical field of mechanical processing, and relates to a design method of a large-suspension-depth and small-diameter double-gear pinion gear grinding tool bar. The method comprises the following steps: considering the tool removal amount of the center of a grinding wheel relative to the end face of a pinion gear during grinding wheel grinding, and also considering the safety distance between the outer edge of the grinding wheel and the end face of a gear to ensure that the outer edge of the grinding wheel does not interfere with the end face of the gear during the feeding and retracting of the tool, and designing the maximum diameter of a repairable grinding wheel; designing the maximum diameter of a quick-change tool bar according to the maximum diameter of the quick-change tool bar, the total tooth height of the pinion gear, the maximum diameter of the grinding wheel, the safety height of the grinding wheel repair, and the reserved repair allowance; projecting the geometric dimensions of the parts to be processed from the pinion gear to the gear direction, determining the geometric relationship between the parts of the gear grinding tool, and determining the minimum suspension depth length of the quick-change tool bar according to the geometric relationship; and adding the minimum suspension depth length, the preset length of the clamping end of the tool bar, and the preset length of the connecting end of the tool bar to obtain the total length of the quick-change tool bar.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanical processing and relates to a design method of a gear grinding tool bar for a small gear of a large-suspension-depth and small-diameter double gear. BACKGROUND

[0002] With the development of science and technology and industrial production, higher requirements are put forward for the machining precision and surface quality of aviation products. High yield, high quality, low consumption, light weight and long service life are the basic goals pursued by the development of aviation engines, and the realization of these goals is based on machining precision and quality. Double gear is more and more widely used in the field of aviation engines and engine accessories due to its advantages of simple structure, high gear transmission ratio and the like.

[0003] Aviation gears belong to single-piece and small-batch processing, and the geometric dimensions of different types of double gears differ greatly. At present, in order to grind the small gear of the double gear, a suitable gear grinding tool bar needs to be designed for each part, which leads to long production preparation time, long tooling design and manufacturing cycle, and high inventory cost. At the same time, in the process of gear grinding, the geometric space is severely limited due to the small distance between the two gears and the large height difference of the gear outer diameter; the rigidity of the gear grinding tool bar is weak, and the tooth shape and tooth direction of the small gear often fail to meet the requirements in the grinding process, which cannot meet the machining requirements of aviation gears above level 4. SUMMARY

[0004] The application aims to provide a design method of a gear grinding tool bar for a small gear of a large-suspension-depth and small-diameter double gear, which solves the problems of long production preparation time, long tooling design and manufacturing cycle, high inventory cost and unstable grinding quality of the gear grinding tool bar.

[0005] TECHNICAL SCHEME

[0006] The design method of the gear grinding tool bar for the small gear of the large-suspension-depth and small-diameter double gear comprises a transfer tool holder, a quick-change tool bar and a dressable grinding wheel; one end of the quick-change tool bar is clamped by the transfer tool holder, and the other end is connected with the dressable grinding wheel; and the transfer tool holder and the dressable grinding wheel of different sizes can be combined and replaced.

[0007] The method comprises the following steps:

[0008] When the grinding wheel is ground, the amount of tool removal of the center of the grinding wheel relative to the end face of the small gear should be considered, and the safety distance between the outer edge of the grinding wheel and the end face of the large gear should also be considered to ensure that the outer edge of the grinding wheel does not interfere with the end face of the large gear during the feeding and retracting of the tool, and the maximum diameter of the dressable grinding wheel is designed;

[0009] The maximum diameter of the quick-change tool bar is designed according to the full tooth height of the small gear, the maximum diameter of the grinding wheel, the safety height of the grinding wheel dressing, and the reserved dressing allowance.

[0010] According to the geometry of the part to be machined, project the part from the small gear to the large gear direction to determine the geometry relationship between the parts of the gear grinding cutter, and determine the minimum overhang length of the quick-change tool bar according to the geometry relationship;

[0011] Add the minimum overhang length, the preset length of the tool bar clamping end, and the preset length of the tool bar connecting end to obtain the total length of the quick-change tool bar.

[0012] The three vertices of the triangle corresponding to the geometry relationship are: the limit contact point of the adapter tool holder and the large gear when the dressable grinding wheel works to the limit position, the center point of the dressable grinding wheel, and the center of the small gear; The minimum overhang is the height of the triangle passing through the limit contact point minus half the thickness of the dressable grinding wheel.

[0013] The quick-change tool bar is locked to the adapter tool holder by a locking nut, and the calculation formula of the minimum overhang length of the tool bar is:

[0014]

[0015] Wherein, L 悬min —The minimum overhang length of the tool bar, R 小 —The dedendum circle radius of the small gear, L—The distance between the large and small gears, L1—The tool removal amount, L2—The safety distance, H2—The reserved dressing amount, R 刀柄 —The radius of the locking nut, R 大 —The addendum circle radius of the large gear, L3—The thickness of the grinding wheel.

[0016] The calculation formula of the maximum diameter of the dressable grinding wheel is:

[0017] Dmax=(L-L1-L2)*2;

[0018] Wherein, Dmax—The maximum diameter of the grinding wheel, L—The distance between the large and small gears, L1—The tool removal amount, L2—The safety distance.

[0019] The calculation formula of the maximum diameter Lmax of the quick-change tool bar is:

[0020] Lmax=Dmax-2*(H+H1+H2);

[0021] Wherein, H—The full tooth height, H1—The safety height.

[0022] The dressable grinding wheel is screwed with the connecting end of the adapter tool holder through a compression nut.

[0023] The thickness of the compression nut is selected according to the preset length of the tool bar connecting end.

[0024] The thickness of the locking nut is selected according to the preset length of the tool bar clamping end.

[0025] Beneficial effects: provide a large suspension depth, small diameter double gear pinion gear grinding tool bar design method, the tool bar can be quickly changed, the length and diameter can be adjusted, and one tool bar can process multiple parts; can solve the problems of long production preparation time, long tooling design and manufacturing cycle, high inventory cost and unstable grinding processing quality. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 For the method step flow chart of the application;

[0027] Figure 2 For the method structure diagram of the application;

[0028] 1-adapter handle; 2-spring collet; 3-locking nut; 4-fast-changing tool bar; 5-repairable grinding wheel; 6-gasket; 7-locking nut.

[0029] Figure 3 For the maximum diameter determination process diagram of the grinding wheel of the method of the application;

[0030] Figure 4 For the maximum diameter determination process diagram of the tool bar of the method of the application;

[0031] Figure 5 For the fast-changing tool bar of the method of the application;

[0032] Figure 6 For the fast-changing tool bar length determination process diagram of the method of the application;

[0033] Figure 7 For the fast-changing tool bar of the method of the application;

[0034] Figure 8 For the method of the application, the compression nut is shown in the figure. DETAILED DESCRIPTION

[0035] A large suspension depth, small diameter double gear pinion gear grinding tool bar design method, through the hierarchical design principle, based on the clamping method of spring collet to get the design method of universal tool bar; including adapter handle, spring collet, locking nut, fast-changing tool bar, repairable grinding wheel, gasket, compression nut, the adapter handle is connected with the machine tool at one end and the tool bar at the other end; the tool bar is divided into clamping part, suspension depth part and connecting part, the clamping part extends into the adapter handle to realize stable connection with the handle, and the connecting part is used for cooperation with the grinding wheel to make the grinding wheel and the tool bar integrated.

[0036] Break the traditional thinking, increase the adapter handle between the machine tool and the tool bar, the adapter handle is connected with the machine tool at one end and the tool bar at the other end, the same handle can clamp different tool bars, and provides the basis for the quick change of the tool bar.

[0037] The tool holder uses a spring clip to clamp the tool shank, which facilitates quick tool shank replacement and effectively saves preparation time.

[0038] The tool holder can be freely adjusted in length, and the appropriate length can be selected according to actual needs. The same tool holder can process different parts, making it highly versatile.

[0039] The diameter and shape of the tool holder can be flexibly designed to adapt to parts with different structures, especially suitable for small hollow helical gears, and can be designed as a concave tool holder for machining.

[0040] The nut is designed as a self-locking nut, which ensures that the grinding wheel does not loosen during the grinding process and increases grinding safety.

[0041] Before assembling the tool holder, dynamic balancing is required, with a dynamic imbalance of ≤0.5g.mm, to ensure that the tool holder does not wobble when running at high speed.

[0042] The tool holder is designed with high-strength materials, with an overall hardness requirement of HRC60 or higher, to enhance the rigidity of the tool holder, reduce the elastic deformation generated when the grinding wheel rotates at high speed, and reduce the vibration of the grinding wheel.

[0043] The method of this invention, based on the principle of hierarchical design and the clamping method of spring clips, obtains a design method for a universal tool holder. This method can complete the grinding of gears with large overhang and small diameter using simple clamping tools, solving the problems of complex design, frequent replacement, and long preparation cycle of grinding tool holders. Applying the method of this invention, it is possible to achieve rapid changeover of grinding tool holders, flexible processing, short preparation time, and strong versatility. It is particularly suitable for single-piece batch production and can effectively reduce processing costs.

[0044] 1. Determine the maximum diameter of the grinding wheel. For example... Figure 3 As shown, during grinding with a grinding wheel, the feed rate L1 of the grinding wheel center relative to the end face of the pinion must be considered to ensure that the teeth at the feed point are completely ground, without any concavity, convexity, or unacceptable tooth profile errors. Simultaneously, the safe distance between the outer edge of the grinding wheel and the end face of the large gear should also be considered to ensure that the outer edge of the grinding wheel does not interfere with the end face of the large gear during the feed and retraction process. The formula for calculating the maximum diameter of the grinding wheel is:

[0045] Dmax=(L-L1-L2)*2 Formula 1

[0046] Where Dmax is the maximum diameter of the grinding wheel.

[0047] L—Distance between the large and small gears

[0048] L1—Output

[0049] L2—Safe Distance

[0050] The distance L between the large gear and the pinion in this example is 21.5 mm, the tool removal amount L1 is set to 1 mm, and the safety distance L2 is set to 1 mm. By substituting the above values into formula 1 mm, the maximum diameter of the grinding wheel is obtained as follows:

[0051] Dmax=(21.5-1-1)*2=39mm.

[0052] 2. Determine the maximum diameter of the tool bar. As shown in Figure 4 , the maximum diameter of the tool bar is related to the whole tooth height of the pinion, the maximum diameter of the grinding wheel, the safety height of the grinding wheel dressing, and the reserved dressing amount. The calculation formula of the maximum diameter of the tool bar is as follows:

[0053] Lmax=Dmax-2*(H+H1+H2) Formula 2

[0054] Where Lmax is the maximum diameter of the tool bar

[0055] Dmax is the maximum diameter of the grinding wheel

[0056] H is the whole tooth height

[0057] H1 is the safety height

[0058] H2 is the reserved dressing amount

[0059] In this example, the outer diameter of the pinion is φ127.45 mm, and the root diameter is φ116.15 mm. Therefore, the whole tooth height H is (127.45-116.15) / 2=5.65 mm. The safety height H1 is set to 2 mm, and the reserved dressing amount H2 is set to 2 mm. Therefore, the maximum diameter of the tool bar is 39-2*(5.65+2+2)=19.7 mm

[0060] 3. Determine the minimum suspension depth length of the tool bar. The suspension depth length of the tool bar has many influencing factors. According to the geometric size of the part to be processed, the structure diagram of the grinding gear (as shown in Figure 6 ) can be drawn by projecting the part from the small teeth to the large teeth direction. It is ensured that the grinding wheel and the grinding wheel adapter bar (mainly concentrated on the outer diameter position of the installation end surface) do not interfere with any part of the part during simulation. In the plane of the large gear end surface, the following geometric relationship diagram, Figure 5 , the triangle.

[0061] The calculation formula of the minimum suspension depth of the tool bar can be derived as follows

[0062] Formula 3

[0063] Where L 悬min is the minimum suspension depth of the tool bar

[0064] R 小 is the root radius of the pinion

[0065] L is the distance between the large gear and the pinion

[0066] L1—Output

[0067] L2—Safe Distance

[0068] H2—Reserved trimming allowance

[0069] R 刀柄 —Locking nut radius

[0070] R 大 — Radius of the tip circle of the large gear

[0071] L3—Grinding wheel thickness

[0072] In this example, the root circle radius R of the pinion is... 小 The diameter is 58.075mm, the distance L between the large and small gears is 21.5mm, the cutting depth L1 is set to 1mm, the safety distance L2 is set to 1mm, the allowable dressing amount H2 is set to 2mm, the locking nut radius R, the tool holder is φ10.5mm, and the large gear addendum circle radius R 大 With R121.475mm and grinding wheel thickness L3 of 10mm, the minimum overhang depth of the tool holder can be obtained as 97.57mm by substituting into the formula.

[0073] 4. Determine the total length of the tool holder. For example... Figure 7 The exploded view of the quick-change tool holder is shown. The formula for calculating the total length of the tool holder is also provided.

[0074] L 刀总 =L 夹持 +L 悬min +L 连接 Formula 4

[0075] Among them, L 刀总 —Total length of the tool holder, L 夹持 —Length of the tool holder clamping section, L 悬min —Minimum overhang length of the tool holder, L 连接 —Length of the tool holder connection section.

[0076] In this example, the length of the clamping part is set to 40mm; the minimum overhang length is calculated as 97.57mm according to Part 3; the length of the connecting part is the sum of the thickness of the selected grinding wheel, the thickness of the shim, and the thickness of the locking nut, set to 10+4+8=22mm; substituting into Formula 4, we can obtain the total length of the tool holder as 40+97.57+22=159.57mm.

[0077] 5. Select appropriate outer diameters for the clamping nut and washer. These should be determined based on the inner diameter of the grinding wheel, the maximum diameter of the grinding wheel, and the maximum diameter of the tool holder. Generally, the washer diameter should be equal to the tool holder diameter, and the outer diameter of the clamping nut should be smaller than the washer diameter.

[0078] 6. The tool holder shall be dynamically balanced. The dynamic imbalance shall be ≤0.3g.mm. If it is not qualified, it is allowed to remove weight in the non-clamping area and non-fitting area. The weight removal position shall be smoothly transitioned and polished.

[0079] 7. Assemble the tool holder, according to... Figure 2 conduct.

[0080] A design method for a small-diameter, double-gear small-tooth grinding tool holder with large overhang is presented. Based on a hierarchical design principle and a spring-coil clamping method, a universal tool holder design is obtained. The main structure comprises seven parts: an adapter tool holder, a spring-coil, a locking nut, a quick-change tool holder, a dressable grinding wheel, a washer, and a clamping nut. It has the following advantages:

[0081] 1. Breaking with traditional thinking, an adapter tool holder is added between the machine tool and the tool holder. One end of the adapter tool holder is connected to the machine tool, and the other end is connected to the tool holder. The same tool holder can clamp different tool holders, providing a basis for rapid tool holder changeover.

[0082] 2. The tool holder uses a spring clip to clamp the tool bar, which facilitates quick tool bar replacement and effectively saves preparation time.

[0083] 3. The tool holder can be freely adjusted in length, and the appropriate length can be selected according to actual needs. The same tool holder can process different parts, making it highly versatile.

[0084] 4. The tool holder is divided into a clamping part, a cantilever part, and a connecting part. The clamping part extends into the adapter tool holder to achieve a stable connection with the tool holder. The connecting part is used to mate with the grinding wheel, making the grinding wheel and the tool holder an integral unit, which can balance flexibility and rigidity. The diameter and shape of the tool holder can be flexibly designed to adapt to parts with different structures, especially suitable for small hollow helical gears, and can be designed as a concave tool holder for machining.

[0085] 5. The nut is designed as a self-locking nut, which can ensure that the grinding wheel does not loosen during the grinding process and increase grinding safety.

[0086] 6. The tool holder must be dynamically balanced before assembly, with a balance accuracy of ≤0.5g.mm, to ensure that the tool holder does not wobble when running at high speed.

[0087] 7. The tool holder is designed with high-strength materials, with an overall hardness requirement of HRC60 or higher, to enhance the rigidity of the tool holder, reduce the elastic deformation generated when the grinding wheel rotates at high speed, and reduce the vibration of the grinding wheel.

Claims

1. A design method for a small-diameter, large-suspension-depth double-gear small-tooth grinding tool holder, characterized in that, The grinding cutter includes: a transfer tool holder (1), a quick-change tool holder (4), and a dressable grinding wheel (5); one end of the quick-change tool holder (4) is held by the transfer tool holder (1), and the other end is connected to the dressable grinding wheel (5). The transfer tool holder (1) and the dressable grinding wheel (5) of different sizes can be combined and replaced. The method includes: When grinding with a grinding wheel, the amount of cutting tool from the center of the grinding wheel relative to the end face of the small gear should be considered. At the same time, the safe distance between the outer edge of the grinding wheel and the end face of the large gear should also be considered to ensure that the outer edge of the grinding wheel does not interfere with the end face of the large gear during the cutting process. The maximum diameter of the dressable grinding wheel (5) is designed. The formula for calculating the maximum diameter of the dressable grinding wheel (5) is: Dmax=(L-L1-L2)*2; where, Dmax—maximum diameter of the grinding wheel, L—distance between the small and large gears, L1—cutting tool amount, L2—safety distance; The maximum diameter of the quick-change tool holder (4) is related to the total tooth height of the pinion, the maximum grinding wheel diameter, the safe height for grinding wheel dressing, and the reserved dressing allowance. The maximum diameter of the quick-change tool holder (4) is designed accordingly. The formula for calculating the maximum diameter Lmax of the quick-change tool holder (4) is: Lmax=Dmax-2*(H+H1+H2); where H—total tooth height, H1—safety height. According to the geometric dimensions of the part to be processed, the geometric relationship between the components of the grinding cutter is determined by projecting from the small tooth to the large tooth direction. Based on the geometric relationship, the minimum overhang length of the quick-change tool holder (4) is determined. The three vertices of the triangle corresponding to the geometric relationship are: the limit contact point between the adapter (1) and the large gear when the dressable grinding wheel (5) is working to the limit position, the center point of the dressable grinding wheel (5), and the center of the small gear. The minimum overhang is the height of the triangle passing through the limit contact point minus half the thickness of the dressable grinding wheel (5). The quick-change tool holder (4) is locked to the adapter (1) by the locking nut (3). The formula for calculating the minimum overhang length of the tool holder is: ; Among them, L 悬min —Minimum overhang length of the tool holder, R 小 —Pin gear root circle radius, L—Distance between pinion and gear, L1—Tool feed rate, L2—Safety distance, H2—Pre-set dressing allowance, R 刀柄 —Lower radius of the locking nut, R 大 — Radius of the tip circle of the large gear, L3 — Thickness of the grinding wheel; Add the minimum overhang length, the preset length of the tool holder clamping end, and the preset length of the tool holder connecting end to obtain the total length of the quick-change tool holder (4).

2. The method according to claim 1, characterized in that, The dressable grinding wheel (5) is screwed to the connecting end of the adapter handle (1) by tightening the nut.

3. The method according to claim 2, characterized in that, The thickness of the clamping nut is selected based on the preset length of the tool holder connection end.

4. The method according to claim 2, characterized in that, The thickness of the locking nut is selected based on the preset length of the tool holder clamping end.

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