A method for numerically controlling the grinding of toroidal worm gear hob teeth and top clearance angle surfaces thereof

Abstract

The present invention discloses a toroidal worm wheel hob cutter tooth and a CNC grinding method for a top clearance angle surface thereof, wherein a single cutter tooth of the hob comprises a top clearance angle surface, a top land surface, a rake surface, a side land surface, a clearance surface and a side clearance angle surface, the hob is mounted on a CNC lathe, and the hob can rotate around a rotary axis S1; the rake surface rotates around S1 by an angle #imgabs0# to obtain a top land line; assuming that the transmission ratio of a double-conical secondary enveloping toroidal worm used in conjunction with the toroidal worm wheel hob is i 12 ; Tool setting steps: align the grinding wheel with the top edge line and make contact with it to complete tool setting; Grinding steps: control the angle of the hob around the C axis to be #imgabs1# and the angle of the grinding wheel tool holder around the B axis to be #imgabs2# to complete grinding. By simultaneously adjusting the angle of the hob, the angle of the tool holder turntable, and the radial and axial distances of the tool holder turntable center relative to the hob center to perform four-axis linkage CNC grinding, the top back angle surface of each tooth can be completely ground to meet the actual use needs.

Description

Technical Field

[0001] The invention relates to a grinding method for a toroidal worm gear hob top clearance angle surface, which belongs to a processing method for a toroidal worm gear hob, and in particular to a numerical control grinding method for a toroidal worm gear hob tooth and a top clearance angle surface thereof. Background Art

[0002] In the field of toroidal worm transmission, the most widely used is the secondary enveloping toroidal worm pair, which has the characteristics of multi-tooth double-line contact and strong load-bearing capacity, providing an effective solution for the needs of miniaturization and lightweight equipment transmission. The worm wheel in the toroidal worm pair is cut by a toroidal worm wheel hob. In order to increase the single service life of the toroidal worm wheel hob, a certain width of the land surface is retained on the top and side of each tooth.

[0003] The top clearance angle surface of the toroidal worm gear hob is a spatial curved surface with a certain clearance angle and a top edge band line as the starting line, which can avoid the interference between the toroidal worm gear hob and the bottom of the tooth root when machining the worm gear tooth root. The teeth of the toroidal worm gear hob are not exactly the same, and the shapes of their top edge band surfaces and top clearance angle surfaces are not exactly the same. At present, manual processing is mostly used in production to obtain the top clearance angle surface, which makes it difficult to guarantee the top edge width and top clearance angle of each tooth. Summary of the invention

[0004] The purpose of the present invention is to propose a method for CNC grinding of toroidal worm gear hob teeth and their top clearance angle surfaces, so as to solve the problem that the top clearance angle surfaces are obtained by manual processing in the prior art, resulting in difficulty in ensuring the top edge width and top clearance angle of each tooth.

[0005] The technical solution of the present invention is as follows:

[0006] The technical solutions adopted to achieve the purpose of the present invention include:

[0007] A method for numerically controlling the grinding of a top clearance angle surface of a toroidal worm gear hob, wherein a single tooth of the hob comprises a top clearance angle surface, a top land surface, a rake surface, a side land surface, a clearance surface and a side clearance angle surface;

[0008] The hob is mounted on a CNC lathe and can rotate around a rotation axis S1; the front cutting edge rotates around S1 by an angle Obtain the top land line;

[0009] Assume that the transmission ratio of the double-conical secondary enveloping toroidal worm used in conjunction with the toroidal worm hob is i 12 ;

[0010] Tool setting steps: Align the grinding wheel with the top edge line and make contact with it to complete the tool setting;

[0011] Grinding steps: Control the angle of the hob around the C axis to The rotation angle of the grinding wheel seat around the B axis is Finish grinding.

[0012] Further, the tool setting step includes:

[0013] Assume that the total number of rake faces of the double-conical secondary enveloping toroidal worm gear hob is m, the number of worm heads is z1, and the value of the n-th tooth is as follows: the throat tooth is the first tooth, and its throat angle is The teeth on the left are 0, -1, -2, -3, etc., and the teeth on the right are 2, 3, 4, 5, etc. For the nth tooth, the C-axis phase angle corresponding to the tool point is: Corresponding B-axis rotation angle: The distance that the tool holder turntable (9) moves along the X axis is: The moving distance along the Z axis is:

[0014] Further, the grinding step includes:

[0015] When grinding the nth tooth, the angle of the hob rotation around the C axis is The rotation angle of the grinding wheel seat around the B axis is At this time along O2O B The increase in distance is Δl, and Δl = R i -R a , O B The distance to O2 becomes R i -(a0+R m ), the corresponding X-axis and Z-axis positions are: in With R i Satisfies the relationship:

[0016] Further, the grinding step includes:

[0017] When grinding the jth tooth, the C-axis rotation angle is increased by the phase angle during tool setting and grinding: That's it.

[0018] Furthermore, the grinding wheel is an arc grinding wheel.

[0019] Furthermore, the width b0 of the arc grinding wheel is greater than the maximum tooth top width of each tooth.

[0020] Furthermore, the B axis of the machine tool is coaxial with the rotation axis S2 of the tool holder turntable (9).

[0021] A toroidal worm wheel hob tooth is prepared by adopting the above-mentioned numerical control grinding method of the top back angle surface of the toroidal worm wheel hob.

[0022] Furthermore, the interval range of the top edge line of the cutter tooth meets the range of 0.59 to 0.63 mm, and the distribution interval range of the top clearance angle of the cutter tooth meets the range of 11.0° to 12.1°.

[0023] The invention adopting the above technical solution has the following advantages:

[0024] The beneficial effect of the present invention is that when a toroidal worm gear hob is ground using a circular arc grinding wheel whose truncated shape is consistent with the toroidal worm gear hob tooth top annular surface, four-axis linkage CNC grinding is performed by simultaneously adjusting the rotation angle of the hob, the rotation angle of the tool holder turntable, and the radial distance and axial distance of the center of the tool holder turntable relative to the center of the hob, so that the top back angle surface of each tooth can be completely ground, and the top back angle surface angle of each tooth can be obtained within a very small range, meeting the needs of actual use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0026] Figure 1 This is a schematic diagram of the tooth structure of a toroidal worm gear hob of the present invention;

[0027] Figure 2 A grinding principle diagram of a method for numerically controlling the back angle surface of a toroidal worm gear hob tooth in the present invention;

[0028] Figure 3 This is a simulation effect diagram of the numerical control machining of a toroidal worm gear hob tooth of the present invention;

[0029] Figure 4 It is a simulation effect diagram of the CNC machining of the edge band and top clearance angle surface of a single tooth in a toroidal worm gear hob cutter of the present invention;

[0030] In the figure: 1-top clearance angle surface, 2-top land surface, 3-front cutting edge surface, 4-side land surface, 5-back cutting edge surface,

[0031] 6—side back angle surface, 7—top edge line, 8—hobbing cutter, 9—tool holder turntable, 10—arc grinding wheel. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that in the drawings or descriptions of the specification, similar or identical parts use the same figure numbers, and the implementation methods not shown or described in the drawings are forms known to ordinary technicians in the relevant technical field. In addition, the directional terms mentioned in the embodiments, such as "upper", "lower", "top", "bottom", "left", "right", "front", "back", etc., are only referenced to the directions of the drawings and are not used to limit the scope of protection of the present invention.

[0033] Example 1

[0034] like Figure 1-4 As shown, a method for grinding the top clearance angle surface of a toroidal worm gear hob of the present invention is provided, wherein a single tooth of a double-conical secondary enveloping toroidal worm gear hob (8) is composed of a top clearance angle surface (1), a top land surface (2), a rake surface (3), a side land surface (4), a clearance surface (5) and a side clearance angle surface (6), and the rake surface (3) is rotated around the axis of the toroidal worm gear hob by an angle of A top edge band line (7) is obtained, and the top edge band line (7) is the intersection line of the top clearance angle surface (1) and the top edge band surface (2), wherein the edge band width is e.

[0035] The rotation axis S1 of the hob (8) intersects the middle plane of its throat perpendicularly at the center point O1. The radius of the tooth root arc of the hob (8) is R a , the center of the circle is O2, O1O2 is the center distance a of the toroidal worm pair, O B The grinding wheel is mounted on the tool holder turntable (9). In this embodiment, the grinding wheel is a circular grinding wheel (10). The rotation axis S0 of the circular grinding wheel (10) is S0. O is the rotation center of the circular grinding wheel (10). In this embodiment, OO B ⊥S0, ensure that the grinding wheel does not deviate.

[0036] O B The distance from O is the grinding wheel distance a0, the arc radius of the truncated arc grinding wheel (10) is the same as the radius of the tooth top ring of the toroidal worm gear hob. In this embodiment, the width b0 of the arc grinding wheel (10) is greater than the maximum tooth top width of each tooth, so that the width of the arc grinding wheel (10) can completely cover the top edge band line (7), and repeated operations are not required during grinding, thereby improving processing efficiency and improving the accuracy of the finished product.

[0037] The maximum radius of the truncated arc grinding wheel (10) is R m The origin of the machine tool is located at point O1. In this embodiment, the B axis of the machine tool is coaxial with the rotation axis S2 of the tool holder turntable (9). This arrangement facilitates the mutual conversion of numerical control parameters during processing, thereby improving the grinding efficiency.

[0038] The C axis of the machine tool is coaxial with the rotation axis S1 of the hob (8), the X axis of the machine tool coincides with the straight line where O1O2 is located, and the Z axis of the machine tool coincides with the rotation axis S1 of the worm; the rotation angle of the tool holder turntable (9) around the B axis is The rotation angle of the hob (8) around the C axis is The coordinate of the tool holder turntable (9) along the X axis is X, the coordinate of the tool holder turntable (9) along the Z axis is Z, B The distance to O2 is adjusted to R a -(a0+R m ).

[0039] At the beginning of tool setting, the total number of rake faces of the double-conical secondary enveloping toroidal worm gear hob is set to m, the transmission ratio is i12, the number of worm heads is z1, and the value of the n-th tooth is as follows: the throat tooth is the first tooth, and its throat angle is The teeth on the left side are 0, -1, -2, -3... respectively, and the teeth on the right side are 2, 3, 4, 5... respectively.

[0040] For the nth tooth, the C-axis phase angle corresponding to the tool setting point is: Corresponding B-axis rotation angle: The distance that the tool holder turntable (9) moves along the X axis is: The moving distance along the Z axis is: The tool setting is completed.

[0041] Grinding starts with grinding the nth tooth, and the angle of the hob around the C axis is The rotation angle of the grinding wheel seat around the B axis is At this time along O2O B The increase in distance is Δl, and Δl = R i -R a , O B The distance to O2 becomes R i -(a0+R m ), the corresponding X-axis and Z-axis positions are:

[0042] in With R i Satisfies the relationship: The coefficient K affects the size of the top clearance angle after relief grinding. When grinding the teeth, the tooth width is set to b1, R gi is the radius of the hob at different axial positions, along O2O B The maximum increase in distance is Δl max =R imax -R a , at the throat, R gi =(aR a ) is the minimum value, at this time The largest increase is

[0043] For the jth hob helical tooth, it is only necessary to increase the rotation angle of the C axis by a certain phase angle during tool setting and grinding: That's it.

[0044] The present invention grinds the toroidal worm gear hob with an arc grinding wheel whose truncated shape is consistent with the toroidal worm gear hob tooth top annular surface. By simultaneously adjusting the rotation angle of the hob, the rotation angle of the tool holder turntable, and the radial distance and axial distance of the center of the tool holder turntable relative to the center of the hob to perform four-axis linkage CNC grinding, the top back angle surface of each tooth can be completely ground, and the top back angle surface angle of each tooth can be obtained within a very small range, which meets the needs of actual use and improves the processing efficiency and processing accuracy.

[0045] Example 2

[0046] The double-cone double enveloping toroidal worm gear hob is used for rolling the worm gear of the double-cone double enveloping toroidal worm pair. The parameters of the double-cone double enveloping toroidal worm are: center distance a = 260mm, transmission ratio i 12 =8, number of worm heads z1 = 5, worm pitch circle diameter d1 = 110mm, number of worm gear teeth z2 = 40, worm gear pitch circle diameter d2 = 410mm, hob tooth top annular radius R a =193.5mm.

[0047] According to the principle of double-conical secondary enveloping toroidal worm, the helical surface of the double-conical secondary enveloping toroidal worm gear hob is processed, including the left and right side helical surfaces, to obtain a blank of the double-conical secondary enveloping toroidal worm gear hob with a front cutting surface (3) and a back cutting surface (5), wherein one of the front cutting surfaces passes through the throat point of the basic toroidal worm helical surface, and a straight front cutting surface is adopted. The back cutting surface is a plane parallel to the front cutting surface, and the distance from the front cutting surface to the back cutting surface is the tooth width b1. The hob is designed with a total number of front cutting surfaces m=10, a total of 10 rows of teeth, and 7 teeth distributed on each spiral. The front cutting surface at the throat tooth is used as the design reference to complete the toroidal worm gear hob blank with a side back angle surface.

[0048] According to the motion parameters of each axis of the machine tool, the CNC machining simulation software Vericut is used to simulate the machining process of the side back angle surface. A four-axis linkage virtual machine tool is established in Vericut, and the double-conical secondary enveloping toroidal worm hob blank with the spiral surface, front cutting surface and back angle surface processed is installed on the C axis of the machine tool; the conical grinding wheel is installed, and the grinding wheel distance a0=164mm, the grinding wheel inclination angle β=0°, the grinding wheel width b0=15mm, and the center distance a=260mm are set. The radius of the grinding wheel section is equal to the radius of the toroidal surface of the toroidal worm hob tooth top, that is, R a =193.5mm, maximum diameter of grinding wheel R m =3.5mm. The angles of the two throats of the hob are

[0049] The first rake face passes through the two throat points and the origin, and the intersection of the rake face and the tooth top annular surface is the cutting edge line; the straight groove rake face is around the hob axis A new plane is obtained, and the intersection line between the new plane and the tooth top annular surface is taken as the top land line.

[0050] When designing and machining each tooth, the maximum incremental rotation angle of the hob around the C axis is The maximum feed arc radius is R max =198.5mm, it can be calculated that K = -8.57° / mm. For the nth tooth, when the annular radius R i From R a Change to R max When the machine tool motion of each cutter tooth is obtained, a series of X and Z values ​​are set, and a four-axis linkage CNC program of B, C, X and Z axes is compiled, and the tooth top clearance angle of each cutter tooth is gradually ground from the top edge band line (7); the top clearance angle surface (1) of each cutter tooth on the hob (8) is adjusted and CNC ground according to the above method, and the grinding of the top clearance angle of each cutter tooth of the hob (8) can be completed.

[0051] The present invention also discloses a toroidal worm gear hob cutter tooth, wherein the top edge line (7) of each tooth has an interval range of 0.59 to 0.63 mm, and the top clearance angle distribution interval range is between 11.0° and 12.1°, thereby ensuring that the top edge width of the top clearance angle surface is consistent with the design value and the consistency of the tooth top clearance angle design.

[0052] The above is a detailed introduction to a method for CNC grinding of a toroidal worm gear hob tooth and its top back angle surface provided by the present invention. The description of the specific embodiment is only used to help understand the method and its core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for numerically controlling the grinding of the top clearance angle surface of a toroidal worm gear hob, wherein a single tooth of the hob comprises a top clearance angle surface (1), a top land surface (2), a rake surface (3), a side land surface (4), a clearance surface (5) and a side clearance angle surface (6), characterized in that: The hob is mounted on a machine tool and can rotate around a rotation axis S1; the front cutting surface (3) rotates around S1 by an angle Obtaining a top land line (7); Assume that the transmission ratio of the double-conical secondary enveloping toroidal worm used in conjunction with the toroidal worm hob is i 12 ; Tool setting steps: Align the grinding wheel with the top edge line (7) and make contact with it to complete the tool setting; Grinding steps: Control the angle of the hob around the C axis to The rotation angle of the grinding wheel seat around the B axis is Finish grinding; Wherein, the tool setting step comprises: Assume that the total number of rake faces (3) of the double-conical secondary enveloping toroidal worm gear hob is m, the number of worm heads is z1, and the value of the n-th tooth is as follows: the throat tooth is the first tooth, and its throat angle is The teeth on the left are 0, -1, -2, -3... teeth, and the teeth on the right are 2, 3, 4, 5... teeth. For the nth tooth, the C-axis phase angle corresponding to the tool point is: Corresponding B-axis rotation angle: The distance that the tool holder turntable (9) moves along the X axis is: The moving distance along the Z axis is:

2. The method for CNC grinding of the top clearance surface of a toroidal worm gear hob according to claim 1, characterized in that: The grinding step comprises: When grinding the nth tooth, the angle of the hob rotation around the C axis is The rotation angle of the grinding wheel seat around the B axis is At this time along O2O B The increase in distance is Δl, and Δl = R i -R a , O B The distance to O2 becomes R i -(a0+R m ), the corresponding X-axis and Z-axis positions are: in With R i Satisfies the relationship:

3. A method for CNC grinding of the top clearance surface of a toroidal worm gear hob according to claim 2, characterized in that: The grinding step comprises: When grinding the jth tooth, the C-axis rotation angle is increased by the phase angle during tool setting and grinding: That's it.

4. The method for CNC grinding of the top clearance angle surface of a toroidal worm gear hob according to claim 1, characterized in that: The grinding wheel is a circular arc grinding wheel (10).

5. The method for CNC grinding of the top clearance surface of a toroidal worm gear hob according to claim 4, characterized in that: The width b0 of the arc grinding wheel is greater than the maximum tooth top width of each tooth.

6. The method for CNC grinding of the top clearance surface of a toroidal worm gear hob according to claim 2, characterized in that: The B axis of the machine tool is coaxial with the rotation axis S2 of the tool holder turntable (9).

7. A toroidal worm gear hob cutter tooth, characterized in that: The method is prepared by using the CNC grinding method of the top back angle surface of the toroidal worm wheel hob according to any one of claims 1 to 6.

8. The toroidal worm gear hob cutter tooth according to claim 7, characterized in that: The range of the top edge line (7) of the cutter tooth meets the requirement of 0.59-0.63 mm, and the range of the top clearance angle of the cutter tooth meets the requirement of 11.0°-12.1°.

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