CN116276323A - A NC Grinding Method for Roller Surface of Cylindrical Roller Convexity Super-precision Guide Roller - Google Patents

Abstract

The invention relates to a numerical control grinding method of a cylindrical roller convexity superfinishing guide roller curved surface, the invention trims the axial profile of the circumferential surface of a flat grinding wheel into a circular arc shape on a numerical control outer circle grinding machine, and the circular arc profile of the grinding wheel is used for grinding the guide roller curved surface according to the envelope grinding principle, and the motion characteristics during grinding are as follows: the guide roller fixed shaft rotates and moves left and right along with the workbench, and the grinding wheel fixed shaft rotates and moves back and forth along with the grinding wheel frame; the grinding wheel axial profile arc center moves along a track curve relative to the guide roller in a plane determined by the grinding wheel frame and the guide roller axis through the linkage of the numerical control two shafts of the grinding wheel frame moving back and forth and the workbench moving left and right, wherein the track curve is an equidistant line of the guide roller profile curve, and the equidistant value is an arc radius value of the grinding wheel axial profile. The axial profile circular arc radius value of the grinding wheel is calculated and determined so as to ensure grinding quality and efficiency. The invention has the outstanding advantages of high grinding precision, high grinding efficiency, high grinding surface quality and the like of the guide roller shape.

Description

A NC Grinding Method for Roller Surface of Cylindrical Roller Convexity Super-precision Guide Roller

technical field

The invention relates to the technical field of mechanical processing and manufacturing, in particular to a numerically controlled grinding method for the curved surface of a cylindrical roller convex super-precision guide roller.

Background technique

Cylindrical roller bearings are widely used in important fields such as aviation, automobiles, and machine tools due to their excellent characteristics such as strong load capacity and high limit speed, and are often key components in major equipment. As the core part of the bearing, the machining requirements of cylindrical rollers are very high. Through-type superfinishing is usually the last process of small and medium-sized cylindrical rollers, which requires machining the roller crown and greatly improving the surface quality of the rollers. The key tooling of this process is the guide roller of the superfinishing machine, which is usually called a cylindrical roller convex superprecision guide roller.

The roll shape of the cylindrical roller crown super-precision guide roll is an axisymmetric surface, and its axial section is called the roll curve, which is usually composed of multiple convex peaks, transition curves between convex peaks, and transition curves between entrances and exits. Among them, the convex The peak curve is used to control the roller penetration trajectory, which directly affects the crown of the roller after superfinishing. The convex curve is a convex curve, but its mathematical expression is complex, and the shape of each convex curve is different, so it is very difficult to precision process.

At present, the roller-shaped curved surface of the guide roller is ground on an ordinary cylindrical grinding machine. The grinding forming principle is to grind out a multi-level straight-profile conical surface to approach the roller-shaped curved surface. The method is to first scratch the surface of the cylindrical guide roller. Line to control the position of each cone, and then by adjusting the horizontal twist angle of the grinder table, use a straight-profile grinding wheel to grind straight-profile cones with different cone angles. This grinding method has limitations such as low roll shape precision, strong dependence of grinding quality on the operator, low processing efficiency, and high labor intensity, which makes it difficult to meet the increasing needs of cylindrical roller superfinishing.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a numerically controlled grinding method for the curved surface of the cylindrical roller convex super-precision guide roller. The grinding method of the present invention not only has high grinding efficiency, but also the grinding guide roller Roll shape precision is high and surface quality is good.

In order to achieve the above object, the specific scheme adopted by the present invention is:

A numerically controlled grinding method for the curved surface of a cylindrical roller convexity super-precision guide roller. On a numerically controlled cylindrical grinding machine, the axial profile of the circumferential surface of the flat grinding wheel is trimmed into an arc shape, and the arc profile of the grinding wheel is used to According to the grinding principle of the envelope method, the roller-shaped curved surface of the guide roller is ground; the movement characteristics during grinding are: the guide roller rotates on a fixed axis and moves left and right with the worktable, the grinding wheel rotates on a fixed axis and moves forward and backward with the grinding wheel frame; through the grinding wheel The CNC two-axis linkage between the front and rear movement of the frame and the left and right movement of the worktable makes the center of the circular arc of the axial profile of the grinding wheel move relative to the guide roller in a plane determined by the axis of the guide roller. The trajectory curve is the guide roller The equidistance line of the curve, and the equidistance value is the radius value of the circular arc of the axial profile of the grinding wheel.

Further, according to the axial truncation curve of each half-peak in each convex peak of the guide roller, a circular arc radius of the axial profile of the grinding wheel that just makes the full width of the grinding wheel can participate in grinding is calculated according to the principle of envelope grinding, Denote it as the full-width contact arc radius of the grinding wheel, compare the full-width contact arc radius of each convex peak with the transition arc radius between adjacent peaks, and select the minimum value as the arc radius value of the axial profile of the grinding wheel.

Beneficial effect:

(1) The guide rollers ground by the grinding method of the present invention have high roll shape accuracy. The invention adopts the grinding principle of the envelope method, and there is no principle processing error in grinding the roll shape. In contrast, the existing grinding method uses multi-level straight-profile conical surfaces to approach the roll-shaped curved surface, and there is principle processing error. In addition, in the existing method, the angular error and the axial position error of the multi-stage conical surface affect the roller grinding accuracy, but these errors do not exist in the method of the present invention.

(2) The surface quality of the curved surface of the guide roller is good when the grinding method of the present invention is used. The method of the present invention can adjust the feed speed and grinding depth through numerical control programming to ensure the surface quality after grinding, while the grinding quality of each level of conical surface in the existing method depends on the naked eye observation of the operator to grasp.

(3) The method of the present invention has high efficiency in grinding the roll shape of the guide roll. The present invention adopts the envelope method for grinding, the grinding process is continuous, and the automation of the grinding process is realized through numerical control programming, so as to achieve high efficiency, while the existing method needs to adjust the grinding position every time one level of conical surface is ground And the angle of the workbench is very labor-intensive and time-consuming, and it is difficult to improve efficiency.

Description of drawings

Figure 1 is a schematic diagram of the guide roll grinding method.

Fig. 2 Schematic diagram of the envelope grinding method for the convex surface of the guide roller.

Fig. 3 is the curve diagram of the guide roller roll shape required by the design of the embodiment.

Fig. 4 is a graph showing the coordinate system of the mathematical expression of the convex peak curve of the guide roller and the geometric meaning of related parameters in the embodiment.

Fig. 5 is a schematic diagram of calculating the arc radius of the axial profile of the grinding wheel.

Icon marks: 1. Guide roller, 2. Grinding wheel, 3. Movement track of the center of the arc center of the axial profile of the grinding wheel, 4. Roller curve of the guide roller, 5. Arc profile of the grinding wheel.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The invention discloses a numerical control grinding method for the curved surface of a cylindrical roller convex super-precision guide roller, which has the outstanding advantages of guide roller grinding accuracy, grinding efficiency and high grinding surface quality.

It should be noted that, from right to left, the axial truncation curves of the guide rollers successively include the first to the Nth convex peak curves arranged at intervals, and the adjacent two convex peak curves are connected by an intermediate transition curve. Connection, the right side of the first peak curve and the left side of the Nth peak curve are also equipped with entrance and exit transition curves, the middle transition curve and the entrance and exit transition curve are usually circular arcs or a combination of circular arcs and straight lines, when the middle transition When the curve or entrance and exit transition curve is a combination of a transition arc and a straight line, the transition arc is tangent to the adjacent convex curve and straight line, and the convex curve is designed according to the through track of the roller during superfinishing.

A numerically controlled grinding method for the curved surface of a cylindrical roller convexity super-precision guide roller. On a numerically controlled cylindrical grinding machine, the axial profile of the circumferential surface of the flat grinding wheel is trimmed into an arc shape, and the arc profile of the grinding wheel is used to According to the principle of enveloping grinding, the roller-shaped curved surface of the guide roller is ground. The movement characteristics during grinding are: the guide roller rotates on a fixed axis and moves left and right with the worktable, the grinding wheel rotates on a fixed axis and moves forward and backward with the grinding wheel frame; The CNC two-axis linkage of forward and backward movement and left and right movement of the worktable makes the arc center of the axial profile of the grinding wheel move relative to the guide roller in a plane determined jointly by the axis of the grinding wheel and the axis of the guide roller. The trajectory curve is the shape of the guide roller The equidistance line of the curve, the equidistance value is the arc radius value of the axial profile of the grinding wheel. It should be noted that the roll shape curve of the guide roll is given by the customer.

The roller-shaped curved surface grinding method of the guide roller of the present invention is shown in Figure 1. The guide roller 1 rotates at a speed of n _and the grinding wheel 2 rotates at a speed of n. The grinding _wheel moves along the axial direction at _a speed of f; the grinding wheel 2 feeds in a radial direction at a speed of _f . Between f _vertical and f _horizontal should meet the CNC two-axis linkage requirements. The circular arc profile of the grinding wheel is trimmed by the grinding wheel dresser.

Further, in order to ensure the grinding quality and efficiency of the roller-shaped curved surface of the guide roller, given the width of the grinding wheel, the axial profile of the grinding wheel is calculated and selected according to the axial section curve of each convex peak of the guide roller and the radius of the transition arc between the convex peaks. The method is: according to the axial truncation curve of each half-peak roll shape in each convex peak of the guide roll, calculate a curve that just makes the full width of the grinding wheel participate in grinding according to the principle of envelope grinding The arc radius of the axial profile of the grinding wheel is called the full-width contact arc radius of the grinding wheel, and the full-width contact arc radius of the grinding wheel is the maximum sand profile arc radius allowed by the curve between the highest point and the lowest point of the grinding peak Based on this, when the guide roller contains N convex peaks, 2N grinding wheel full-width contact arc radii can be calculated, and the full-width contact arc radius of the grinding wheel of each convex peak and the transition arc radius between adjacent convex peaks (In the guide roller, the radii of the transition arcs between the first and the Nth convex peaks are all equal) for comparison, the minimum value is selected as the arc radius value of the axial profile of the grinding wheel.

The technical principle of the present invention is the principle of envelope method grinding. The roller-shaped curved surface of the guide roller is an axisymmetric curved surface. The grinding principle of the envelope method is shown in Figure 2. The contour of the peripheral surface of the grinding wheel is trimmed into a section of arc curve, and the center of the arc is equidistant along the roller-shaped curve of the guide roller. line movement, the equidistant value is the radius of the arc, then the envelope line after the arc profile of the grinding wheel moves is theoretically the roll curve of the guide roller. During the grinding process, the circular arc profile of the grinding wheel is always tangent to the roll curve, and the tangent point is the grinding point. While the grinding point moves on the circular arc profile of the grinding wheel, it also moves on the roller curve of the guide roller. As shown in Figure 2, as the arc center of the grinding wheel moves along the trajectory line, the grinding point is successively located at points a, b, and c on the arc of the grinding wheel, and correspondingly, it is successively located at points a ₁ and b ₁ on the roller curve , c ₁ point. In order to ensure that the full length of the roll curve is ground, a ₁ point and c ₁ point should be located at the starting point and end point of the full length of the busbar. The arc length from point a to point c is called the grinding arc length of the grinding wheel, which is the arc length of the grinding wheel that actually participates in grinding when the grinding wheel grinds this section of roller curve. Increasing the grinding arc length of the grinding wheel can improve the utilization rate of the grinding wheel, improve the grinding efficiency and slow down the local wear of the grinding wheel, but the arc length cannot exceed the range of the arc length of the grinding wheel limited by the width of the grinding wheel.

When the roller penetration track is a circular arc, the mathematical expression of the convex curve is:

The coordinate system of expression (1) and the geometrical meaning of related parameters are as shown in accompanying drawing 4, in formula (1) and accompanying drawing 4, A and A ₁ are respectively the circle center of front and rear guide roller throat sections, and coordinate origin O is located at its connecting line At the midpoint, the Y ₁ axis coincides with the line segment AA ₁ and is located in the horizontal plane, the Z ₁ axis is vertically upward, and OX ₁ Y ₁ Z _I is an orthogonal rectangular coordinate system. The center of the throat section of the front and rear guide rollers is the two closest points on the axis of the front and rear guide rollers. The radius of the guide roller in the throat section is called the throat diameter, which is represented by R ₀ . Point B is any point on the axis of the guide roller, x is the value from any point B to the throat of the guide roller, the radius of the guide roller at this point is y, point _B1 is the point on the axis of the leading guide roller that is ₁ x away from point A, d Point D is the highest point of the roller center penetrating track, point D is the point corresponding to the axis of the guide roller at the highest point of the roller center penetrating track, λ indicates the inclination angle of the guide roller in the vertical plane, and γ ₀ indicates the rolling angle of the guide roller throat section. The contact angle between the roller and the guide roller, r _w is the radius of the cylindrical roller, d _h is the drop of the roller center through the track at the point corresponding to x, ε is the clip between the horizontal projection of the roller motion track and the horizontal projection of the guide roller axis R is the radius of the arc of the roller penetration track; m is the transverse length from the highest point of the arc of the roller penetration track to the throat position, and n represents the half length of the guide roller.

It should be noted that the processing parameters given by the customer include the values of the parameters contained in formula (1), which are based on the geometric parameters of the cylindrical roller to be processed, the convexity, the geometric parameters of the guide roller, and the guide roller and roller The positional relationship is determined.

As a specific example, the roll shape curve of the guide roll required by the ultra-precision design of the crown of a certain type of roller given by the customer is shown in Figure 3. The entire roll shape curve includes 4 sections of convex peak curves, 8 sections of transition arcs and 5 sections of transition straight lines, which are symmetrically distributed relative to the length center of the guide roller. Figure 3 only shows the roll shape curve of the half length of the guide roller. The parameters related to the shape of the guide roller are: the throat diameter _R0 is 77.5mm, the half-length n of the guide roller is 470mm, the inclination angle λ of the guide roller in the vertical plane is 1°, the distance between the roller and the guide roller in the throat section of the guide roller The contact angle γ ₀ is 16.5°, the radius r _w of the cylindrical roller is 4mm, the arc radius R of the roller penetration track is 730mm and 500mm at the first and second convex peaks respectively, and the roller corresponding to the first convex peak of the guide roller The arc radius R of the through track is 730mm, and the x coordinate of the arc high point is 325.5mm; the arc radius R of the roller track corresponding to the second convex peak of the guide roller is 500mm, and the x coordinate of the arc high point is 108.5mm, the first, The working ranges of the two convex peaks in the x coordinate direction are 97mm and 93mm respectively. The radius of the transition arc between adjacent peaks is 1057mm.

Using a CNC cylindrical grinder with a 15° included angle between the axis of the grinding wheel and the moving direction of the worktable, the width B of the given grinding wheel is 50 mm, and the roll curve of the guide roller of the embodiment is CNC-ground. The method is as follows.

Calculate and determine the radius r of the axial profile of the grinding wheel. Accompanying drawing 5 is the schematic diagram of calculating the arc radius of the sand profile. In the figure, B is the width of the grinding wheel, O point is the highest point of the convex curve, and its tangent is a horizontal line, and A point is the lowest point of the guide roller convex curve, and its tangent is opposite to The angle of inclination to the horizontal is θ. When the grinding point is at point A of the convex peak curve of the guide roller, it is just at the edge of the width of the grinding wheel on the sand profile arc; and when the grinding point is at point O of the convex peak curve of the guide roller, the grinding point is on the arc of the grinding wheel Silhouetted at the center of its width.

According to the calculation principle diagram of the arc radius of the axial profile of the grinding wheel shown in Fig. 5, for any convex curve, the full-width contact arc radius r of the grinding wheel is

where θ can be calculated according to the peak curve expression (1) and related roll shape parameters. The expression of the slope of any point of the convex peak curve can be obtained by deriving the formula (1) as follows

In formula (3),

y ₄ =(R ₀ +r _w )sinγ ₀ -d _h

y ₅ = d _h '

According to the x-coordinate of the lowest point A of the convex peak curve of the guide roller and other roller shape parameters given above, θ can be obtained by using formula (3), and the corresponding full-width contact arc of the grinding wheel can be calculated by using formula (2) Radius r value.

There are 2 lowest points in each convex peak curve, and there are 2 convex peaks on the half-length of the guide roller in the embodiment, and there are 4 lowest points in total. Correspondingly, the radius r of the full-width contact arc of the 4 grinding wheels can be calculated as 1057mm respectively. , 1096mm, 1384m, 1713mm. The radii of each transitional arc are the same, both being 1057mm. Select the smallest one among the 4 full-width contact arc radius r values of the grinding wheel and each transition arc radius value, and determine that the grinding wheel axial profile arc radius r is 1057mm during grinding.

The full-width contact arc radius r value of the grinding wheel calculated according to formula (2) is the maximum sand profile arc radius value allowed by the curve between the highest point and the lowest point of the grinding convex peak. When there are two convex peaks , it is possible to calculate the r value of the full-width contact arc radius of the four grinding wheels. If the arc radius of the sand profile is greater than this value, it cannot be guaranteed that the grinding wheel is always tangent to the convex peak curve during the grinding process, which is not a complete envelope grinding. If the arc radius of the sand profile is smaller than this value, complete envelope grinding can be achieved, but the grinding point cannot reach the edge of the width of the grinding wheel at the lowest point of the convex curve, and the utilization rate of the grinding wheel will be lower. Comparing the full-width contact arc radius of the grinding wheel of each convex peak with the transition arc radius between adjacent peaks, the minimum value is selected as the arc radius value of the axial profile of the grinding wheel, that is, under the premise of ensuring complete envelope grinding, Make the utilization rate of the grinding wheel the highest, so as to ensure the grinding quality and efficiency of the guide roller.

Based on the roll shape curve shown in Figure 3, the equidistant line is taken according to the radius value of the arc of the axial profile of the grinding wheel 1057mm, as the track curve of the center of the arc of the axial profile of the grinding wheel relative to the movement of the guide roller, and the numerical control program is compiled, namely The precision grinding of the roll shape of the guide roller in this embodiment can be realized on the numerical control grinding machine.

In order to further improve the overall grinding efficiency of the roller-shaped curved surface of the guide roller, a rough grinding process can be arranged before the precision grinding of the above-mentioned roller-shaped curve. The rough grinding process can use the plunge method to grind most of the margin of the intermediate transition curve and the transition curve of the entrance and exit.

This application does not require that the angle between the axis of the grinding wheel and the moving direction of the worktable must be 15°. It is also applicable to CNC grinding machines where the axis of the grinding wheel is parallel to the moving direction of the worktable or the angle is other values, as long as the 15° in the formula (2) Just change the included angle to 0° or other corresponding values.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. All equivalent changes or modifications made according to the essence of the present invention shall fall within the protection scope of the present invention.

Claims (2)

1. A numerical control grinding method for a cylindrical roller convexity superfinishing guide roller curved surface is characterized in that on a numerical control outer circle grinding machine, the axial profile of the circumferential surface of a flat grinding wheel is trimmed to be circular arc, and the circular arc profile of the grinding wheel is used for grinding the guide roller curved surface according to an envelope grinding principle;

the motion characteristics during grinding are as follows: the guide roller fixed shaft rotates and moves left and right along with the workbench, and the grinding wheel fixed shaft rotates and moves back and forth along with the grinding wheel frame; the grinding wheel axial profile arc center moves along a track curve relative to the guide roller in a plane determined by the grinding wheel frame and the guide roller axis through the linkage of the numerical control two shafts of the grinding wheel frame moving back and forth and the workbench moving left and right, the track curve is an equidistant line of the guide roller profile curve, and the equidistant value is the radius value of the grinding wheel axial profile arc.

2. The numerical control grinding method for the cylindrical roller convexity superfinishing guide roller curved surface is characterized in that for the axial truncated curve of each half peak in each convex peak of the guide roller, a grinding wheel axial profile arc radius which just enables the full width of the grinding wheel to participate in grinding is calculated according to an envelope grinding principle and is recorded as the full width contact arc radius of the grinding wheel, the full width contact arc radius of the grinding wheel of each convex peak is compared with the transition arc radius between the adjacent convex peaks, and the minimum value is selected as the axial profile arc radius value of the grinding wheel.

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