CN116900421A - An unequal rake angle cutting tool and its construction method - Google Patents

Abstract

The invention discloses an unequal rake angle tooth cutting tool in the field of tooth cutting tool construction and a construction method thereof. It consists of a surface and a flank surface; the cutting edge is located on the conjugate surface of the machined tooth surface; the rake surface is located in the area close to the cutting edge and is a free-form surface with a rake angle that changes regularly, and other areas of the rake surface are filled curved surfaces ; The flank surface is a free-form surface composed of multiple cutting edges; the cutter teeth are helical teeth, and the rotation direction of the cutter teeth is one of left-hand or right-hand rotation, and the rotation angle is 10‑30°; the front tool in the cutting edge field The surface is a free-form surface with a non-constant rake angle; starting from the gear cutting tool body, the gear cutting tool body is constructed. The tooth cutting tool constructed by this construction method has high tooth surface machining accuracy and can The non-uniform wear trend of the cutter teeth is evened out, giving the cutter a longer life and reducing costs.

Description

An unequal rake angle cutting tool and its construction method

Technical field

The invention belongs to the field of tooth cutting tool construction, specifically a tooth cutting tool with unequal rake angles and a construction method thereof.

Background technique

Gear cutting technology is a new gear processing technology that has gradually developed in the 21st century. It can not only realize the processing of lightweight gear parts such as internal teeth without undercut grooves, double gears, but also can achieve dry cutting, and the processing accuracy reaches GB/T6 level and above. Above, the processing efficiency is 3-4 times higher than that of gear hobbing and gear shaping, showing significant features such as high precision, high efficiency, and green environmental protection. However, there are some problems in the industrialization process of tooth cutting technology, that is, the tooth cutting knife wears quickly and has a short service life.

In order to solve the above problems, Chinese patent publication number CN116197466A discloses a tooth cutting tool and a preparation method thereof. The tooth cutting tool includes: a tooth cutting tool body, the blade surface of the tooth cutting tool body is formed with multiple concave and convex structures, and the multiple concave and convex structures are arranged at intervals along at least one direction on the blade surface; and a composite film layer, which is provided on the blade surface , and the composite film layer includes: a metal film layer, formed on the blade surface, and covering the surface of multiple concave and convex structures, the material of the metal film layer includes metal; a transition film layer, arranged on the side of the metal film layer away from the blade surface, The transition film layer includes a first film layer formed on the metal film layer and a second film layer formed on the first film layer. The material of the first film layer includes metal nitride, and the material of the second film layer includes metal and Nitride of an alloy of aluminum; and a functional film layer, which is provided on the side of the transition film layer away from the blade surface. The material of the functional film layer includes nitride of an alloy of metal, aluminum and silicon.

The above device adds multiple layers of film to the tool body to slow down the wear of the gear cutting tool and improve the service life of the gear cutting tool. This method is costly; therefore, it is necessary to propose a gear cutting tool with unequal rake angles and Its construction method is to construct the gear cutting tool body based on the gear cutting tool body. The unequal rake angle gear cutting tool constructed by this construction method has high tooth surface processing accuracy and can even out the non-uniformity of the blade teeth. The uniform wear trend makes the tool have a higher life and reduces the cost.

Contents of the invention

The object of the present invention is to propose a tooth cutting tool with unequal rake angles and a construction method thereof. Starting from the tooth cutting tool body, the tooth cutting tool body is constructed. The unequal rake angle tooth cutting tool constructed by this construction method has It has high tooth surface machining accuracy and can even out the non-uniform wear trend of the cutter teeth, giving the tool a longer life and reducing costs.

In order to achieve the above object, the technical solution of the present invention is as follows: an unequal rake angle cutting tool and its construction method, including a tool body and a number of teeth evenly distributed along the axial direction of the tool body; wherein, the teeth are composed of a cutting edge, It consists of a rake surface and a flank surface; the cutting edge is located on the conjugate surface of the machined tooth surface; the rake surface is located in the area close to the cutting edge and is a free-form surface with a rake angle that changes regularly. The other areas of the rake surface are Filled surface; the flank surface is a free-form surface composed of multiple cutting edges.

Furthermore, the blade teeth are straight teeth.

Furthermore, the cutter teeth are helical teeth, and the rotation direction of the cutter teeth is either left-hand or right-hand, and the rotation angle is 10-30°; the rake surface in the cutting edge field is a free-form surface with a non-constant rake angle; The rake angle is 3-30°, and the cutting rake angle of the cutting edge is -5-25°; the width of the flank surface gradually decreases from the front end of the tool body to the rear end of the tool body, and the relief angle of the tool body is 6-10 °.

Further, the construction method of the non-equal rake angle cutting tool includes the following steps:

Step 1: Establish the cutting edge; establish the conjugate surface of the machined tooth surface according to the workpiece parameters and processing parameters, select some points on the conjugate surface according to the constraints as the shape value points of the cutting edge, and perform splines on the shape value points Curve fitting obtains a spatial curve;

Step 2: Establish the rake face; calculate the working zone of the cutting rake angle at each edge point based on the processing parameters and the cutting edge obtained in step 1; construct the rake face according to the definition of the cutting rake angle and the design value of the lower limit of the cutting rake angle working zone Generating vector of

Among them, the definition of cutting rake angle refers to: establishing a tool cutting angle coordinate system at any point on the cutting edge curve. According to metal cutting theory, the angle between two straight lines in the main section is the cutting rake angle;

The selection conditions for the lower limit of the cutting rake angle working zone are: based on the calculation of the working zone of the cutting rake angle at each edge point, determine the minimum value of the global cutting rake angle as the lower limit of the cutting rake angle working zone;

Step 3: Establish the flank surface; calculate the change in center distance after each regrinding based on the set change in the cutting edge tooth tip position after each regrinding and the design relief angle of the tool, and obtain the weight according to the method in step 1. The cutting edge after grinding;

Repeat the above steps to obtain several reground cutting edges. According to the shape value points on each cutting edge, a cubic B-spline surface is constructed through interpolation. The cubic B-spline surface is the flank surface.

Furthermore, the calculation method for calculating the working zone of the cutting rake angle of each edge point is as follows: substituting the cutting edge into the cutting motion equation of gear cutting.

Further, the workpiece parameters include workpiece module, number of teeth, helix angle, tooth tip circle diameter, tooth root circle diameter, base circle diameter, index circle diameter, span-rod distance and common normal; processing parameters include rotation speed and axis intersection angle.

Furthermore, the re-sharpened left and right cutting edges are still conjugate with the left and right tooth surfaces of the workpiece respectively.

Furthermore, in step one, the constraints refer to: the axial cutting distance of the workpiece tooth surface and the height difference of the tool cutting edge.

Furthermore, the selection conditions for some points are: the range of available points can be calculated according to the constraints, and the points are selected uniformly within this range.

Furthermore, in step three, the change in the position of the cutting edge tip after each regrinding and the design method of the tool are: several regrinding cutting edges located on the theoretical conjugate surface are used to form the flank surface to ensure that the regrinding The consistency of the blade shape accuracy after regrinding; the position of the conjugate surface where the cutting edge is located after regrinding changes accordingly compared with before regrinding. By adjusting the center distance between the tool and the workpiece, several theoretical conjugates after regrinding are obtained noodle.

After adopting the above solution, the following principles and beneficial effects are achieved:

(1) The present invention starts from the gear cutting tool body and constructs the gear cutting tool body. The unequal rake angle gear cutting tool provided by this construction method has no theoretical machining error and has high tooth surface processing accuracy.

(2) The tooth-cutting cutter provided by the present invention has unequal rake angles, which can even out the non-uniform wear trend of the cutter teeth and make the cutter have a higher service life.

(3) The cutting edge of the unequal rake angle cutting tool provided by the present invention is still conjugate with the processed tooth surface after re-sharpening, and the processing accuracy remains constant after re-sharpening.

(4) The design method provided by the present invention can effectively reduce the cutting resistance of the tooth-cutting tool and reduce the vibration of the machine tool, thereby improving the processing quality of the part surface and achieving higher processing accuracy.

(5) The design method provided by the present invention is versatile and suitable for processing various involute and non-involute internal and external cylindrical gears.

Description of the drawings

Figure 1 is a schematic structural diagram of a tooth cutting tool according to an embodiment of the present invention.

Figure 2 is a schematic structural diagram of the teeth of a cutting knife according to an embodiment of the present invention.

Figure 3 is a schematic diagram of the structure of the cutting edge located on the conjugate surface of the tooth surface to be processed according to the embodiment of the present invention.

Figure 4 is a schematic diagram of the cutting rake angle working belt according to the embodiment of the present invention.

FIG. 5 is a schematic diagram of the cutting angle reference plane according to the embodiment of the present invention.

Figure 6 is a schematic diagram of a rake surface formation method according to an embodiment of the present invention.

Figure 7 is a schematic diagram of the formation method of the flank surface according to the embodiment of the present invention.

Detailed ways

The following is further detailed through specific implementation methods:

The reference numbers in the drawings of the description include: tool body 1, tooth 2, cutting edge 201, rake surface 202, flank surface 203, conjugate surface 3, tool rake angle 6, and filled curved surface 9.

The embodiment is basically as shown in Figures 1-7:

An unequal rake angle cutting tool and its construction method, including a tool body 1 and a number of teeth 2 evenly distributed along the axial direction of the tool body 1; wherein, the teeth 2 are composed of a cutting edge 201, a rake surface 202 and a flank It consists of 203 faces.

The cutting edge 201 is located on the conjugate surface 3 of the processed tooth surface; the rake surface 202 is located in the area close to the cutting edge 201. The rake surface 202 is a free-form surface with a rake angle that changes regularly. The other areas of the rake surface 202 are Filling curved surface 9; flank surface 203 is a free-form surface composed of multiple cutting edges 201.

The cutter teeth 2 are straight teeth or helical teeth. In this embodiment, the cutter teeth 2 are helical teeth. The rotation direction of the cutter teeth 2 is one of left-handed or right-handed, and the rotation angle is 10-30°; the cutting edge 201 area The rake surface 202 inside is a free-form surface with a non-constant rake angle; the tool rake angle 6 is 3-30°, and the cutting rake angle of the cutting edge 201 is -5-25°; the width of the flank surface 203 varies from the tool body 1 The front end to the rear end of the tool body 1 gradually decreases, and the clearance angle of the tool body 1 is 6-10°.

The construction method of a non-equal rake angle cutting tool includes the following steps:

Step 1: Establish the cutting edge 201; establish the conjugate surface of the machined tooth surface according to the workpiece parameters and processing parameters, select some points on the conjugate surface according to the constraints as the shape value points of the cutting edge 201, and conduct the shape value points Spline curve fitting obtains a spatial curve;

Step 2: Establish the rake face 202; calculate the working zone of the cutting rake angle at each edge point according to the processing parameters and the cutting edge 201 obtained in step 1; according to the definition of the cutting rake angle and the design value of the lower limit of the cutting rake angle working zone, construct the front The bus vector of the blade surface 202; through the bus vector, use the cutting edge 201 obtained in step 1 as a conductor to construct a free-form surface in the area of the cutting edge 201;

Among them, the definition of cutting rake angle refers to: establishing a tool cutting angle coordinate system at any point on the cutting edge curve. According to metal cutting theory, the angle between two straight lines in the main section is the cutting rake angle; as shown in the figure As shown in 5, these two straight lines are the tangent No of the intersection of the main section Po and the rake face and the intersection N1 of the main section Po and the base plane Pr;

The selection conditions for the lower limit of the cutting rake angle working zone are: based on the calculation of the working zone of the cutting rake angle at each edge point, determine the minimum value of the global cutting rake angle as the lower limit of the cutting rake angle working zone;

Step 3: Establish the flank surface 203; calculate the change in center distance after each regrinding based on the set change in the tip position of the cutting edge 201 after each regrinding and the design relief angle of the tool, follow the method in step 1 Obtain the reground cutting edge 201; repeat the above steps to obtain several reground cutting edges 201, and construct a cubic B-spline surface through interpolation according to the shape value point on each cutting edge 201. The cubic B-spline surface This is the flank surface 203.

The calculation method for calculating the working zone of the cutting rake angle of each edge point is as follows: Substituting the cutting edge 201 into the cutting motion equation of tooth cutting; the workpiece parameters include workpiece module, number of teeth, helix angle, tooth tip circle diameter, tooth root circle diameter, Base circle diameter, indexing circle diameter, cross-rod distance and common normal; processing parameters include rotation speed and axis intersection angle; the left and right cutting edges 201 after re-sharpening are still conjugate with the left and right tooth surfaces of the workpiece respectively.

The constraints refer to: the axial cutting distance of the workpiece tooth surface and the height difference of the tool cutting edge.

The selection conditions for some points are: the range of available points can be calculated according to the constraints, and the points are selected evenly within this range.

In step three, the change in the position of the cutting edge tooth tip after each regrinding and the design method of the tool are as follows: several regrinding cutting edges located on the theoretical conjugate surface are used to form the flank surface to ensure that the cutting edge tooth tip position changes after regrinding. Consistency of blade shape accuracy; the position of the conjugate surface where the cutting edge is located after regrinding changes accordingly compared to before regrinding, and several theoretical conjugate surfaces after regrinding are obtained by adjusting the center distance between the tool and the workpiece; As shown in Figure 3, the initial cutting edge and the cutting edge after several regrindings are represented by e1, e2... respectively; the conjugate surfaces where these cutting edges are located are represented by c1, c2... respectively; the teeth on each cutting edge The vertices are represented by M11, M22... respectively. The distance between the tooth vertices of adjacent cutting edges is represented by Δg, and its value can be set according to the tool relief angle.

The specific implementation process is as follows:

In this embodiment, the cutter teeth 2 are helical teeth, in which the rotation direction of the cutter teeth 2 is either left-handed or right-handed, and the rotation angle is 10-30°.

According to the conjugation principle, a conjugate surface 3 model of the machined tooth surface is established. Some points on the conjugate surface 3 are selected as cutting edge 201 shape value points according to the constraints. These shape value points are fitted with spline curves to obtain A spatial curve passing through these shape value points is the cutting edge 201.

Combining the processing parameters such as rotation speed and axis intersection angle, and substituting the cutting edge 201 into the cutting motion equation of gear cutting, the cutting rake angle working zone of the cutting edge 201 can be calculated. As shown in Figure 4, each edge point on the cutting edge 201 corresponds to Respective rake angle working bandwidth;

As shown in Figure 5, the normal vector of the rake face 202 is established at each point on the cutting edge 201 so that the working zone of the cutting rake angle is between -5-25°; the normal vector of the rake face 202 at each point is connected with the blade The cross product of the tangent vector of the line is obtained to obtain a tiny line segment within the area of the cutting edge 201.

As shown in Figure 6, the cutting edge 201 is used as the conductor of the ruled surface, and the tiny line segments in the area of the cutting edge 201 are used as the generatrix of the ruled surface to form a rake surface 202 in the form of a free-form surface. The tool rake angle 6 is 3- 30°. The other areas of the rake surface 202 are filled curved surfaces 9; as shown in Figure 7, the flank surface 203 gradually decreases from the front end of the tool to the rear end, and is constructed from a free-form surface formed by cubic B-spline fitting of several cutting edges 201. Take out tooth 2.

The above are only embodiments of the present invention. Common knowledge such as the specific structures and characteristics of the solutions are not described in detail here. Those of ordinary skill in the art are aware of all common knowledge in the technical field to which the invention belongs before the filing date or priority date. Technical knowledge, being able to know all the existing technologies in the field, and having the ability to apply conventional experimental methods before that date. Persons of ordinary skill in the field can, under the inspiration given by this application, combine their own abilities to perfect and implement this plan, Some typical well-known structures or well-known methods should not be an obstacle for those of ordinary skill in the art to implement the present application. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention. These should also be regarded as the protection scope of the present invention and will not affect the implementation of the present invention. effectiveness and patented practicality. The scope of protection claimed in this application shall be based on the content of the claims, and the specific implementation modes and other records in the description may be used to interpret the content of the claims.

Claims (10)

1. A non-equal rake angle gear cutting tool is characterized in that: comprises a cutter body and a plurality of cutter teeth which are uniformly distributed along the axial direction of the cutter body; wherein, the cutter tooth is composed of a cutting edge, a front cutter surface and a rear cutter surface; the cutting edge is positioned on the conjugate surface of the machined tooth surface; the front cutter surface is positioned in the field close to the cutting edge, is a free curved surface with a front angle according with regular change, and other areas of the front cutter surface are filled curved surfaces; the clearance surface is a free curved surface formed by a plurality of cutting edges.

2. The unequal rake tooth cutter of claim 1, wherein: the cutter teeth are straight teeth.

3. The unequal rake tooth cutter of claim 1, wherein: the cutter teeth are helical teeth, the rotation direction of the cutter teeth is one of left rotation or right rotation, and the rotation angle is 10-30 degrees; the rake face in the cutting edge field is a free-form surface with a non-constant rake angle; the front angle of the cutter is 3-30 degrees, and the cutting front angle of the cutting edge is-5-25 degrees; the width of the rear cutter face gradually decreases from the front end of the cutter body to the rear end of the cutter body, and the rear angle of the cutter body is 6-10 degrees.

4. A construction method of a non-equal-front-angle tooth cutting tool is characterized by comprising the following steps of: a method of constructing a non-equal rake tooth cutter according to any one of claims 1 to 3, comprising the steps of:

step one: establishing a cutting edge; establishing a conjugate curved surface of a machined tooth surface according to workpiece parameters and machining parameters, selecting partial points on the conjugate curved surface as shape value points of a cutting edge according to constraint conditions, and performing spline curve fitting on the shape value points to obtain a space curve;

step two: establishing a rake face; calculating a working belt of the cutting front angle of each cutting edge point according to the machining parameters and the cutting edge obtained in the step one; constructing a bus vector of the rake face according to the definition of the cutting rake angle and the design value of the lower limit of the cutting rake angle working band; constructing a free-form surface in the field of the cutting edge by taking the cutting edge obtained in the step one as a lead through a bus vector;

wherein, the definition of the cutting rake angle refers to: a cutter cutting angle coordinate system is established at any point on a cutting edge curve, and according to a metal cutting theory, an included angle between two straight lines in a main section is a cutting front angle;

the lower limit of the cutting front angle working band is selected as follows: according to the working band of the cutting front angle of each blade point, determining the minimum value of the global cutting front angle as the lower limit of the working band of the cutting front angle;

step three: establishing a rear cutter surface; calculating the change of the center distance after each regrinding according to the set change of the tooth top position of the cutting edge after each regrinding and the design relief angle of the cutter, and acquiring the cutting edge after regrinding according to the method of the step one;

repeating the steps to obtain a plurality of re-ground cutting edges, and constructing a cubic B-spline surface by interpolation according to the shape value point on each cutting edge, wherein the cubic B-spline surface is the rear cutter surface.

5. The method for constructing the unequal front angle gear cutting tool according to claim 4, wherein: the working band calculating method for calculating the cutting front angle of each blade point comprises the following steps: substituting the cutting edge into a cutting motion equation of tooth cutting machining.

6. The method for constructing the unequal front angle gear cutting tool according to claim 5, wherein: the workpiece parameters comprise workpiece modulus, tooth number, helix angle, tooth top circle diameter, tooth root circle diameter, base circle diameter, reference circle diameter, cross bar distance and common normal; the processing parameters include rotational speed and intersection angle.

7. The method for constructing the unequal front angle gear cutting tool according to claim 6, wherein: the left and right cutting edges after resharpening are still respectively conjugated with the left and right tooth surfaces of the workpiece.

8. The method for constructing a non-equal rake tooth cutter as claimed in claim 7, wherein: in step one, the constraint condition means: the axial cutting distance of the tooth surface of the workpiece and the height drop of the cutting edge of the cutter.

9. The method for constructing the unequal front angle gear cutting tool according to claim 8, wherein: the selection conditions of the partial points are as follows: the range of available points can be calculated according to the constraint conditions, and the available points are uniformly selected in the range.

10. The method for constructing the unequal front angle gear cutting tool according to claim 9, wherein: in the third step, the variation of the tooth top position of the cutting edge after each regrinding and the design method of the cutter are as follows: a plurality of regrinding cutting edges positioned on the theoretical conjugate plane are adopted to form a rear cutter surface, so that consistency of edge shape precision after regrinding is ensured; the position of the conjugate surface of the regrinded cutting edge is correspondingly changed compared with that of the conjugate surface before regrinding, and a plurality of theoretical conjugate surfaces after regrinding are obtained by adjusting the center distance between the cutter and the workpiece.