CN207982928U - The caliberating device of contact on-line detecting system for lathe - Google Patents

Abstract

The utility model discloses a calibration device for a contact type on-line detection system of a lathe, which comprises a clamping shaft and an L-shaped device main body; one end of the clamping shaft is used for lathe chuck clamping, and the other end is as long as the L-shaped device main body. The top of the side is connected, and the central axis of the clamping shaft is collinear with the center line of the long side of the L-shaped device body; the bottom end of the L-shaped device body is provided with a stepped hole and the first hole; the central axis of the first hole, the clamping shaft The central axis of the center axis and the center line of the long side of the L-shaped device body are collinear and coincide with the center of rotation of the lathe spindle; the stepped hole is composed of a through hole at the top and a second hole at the bottom; the central axis of the through hole and the second hole The central axis of the hole is collinear and parallel to the center of rotation of the lathe spindle; the line connecting the center of the first hole and the through hole is parallel to the transverse feed direction of the lathe; the central axis of the through hole is parallel to the central axis of the first hole. The device is suitable for a contact-type online detection system of a two-axis horizontal CNC lathe through structural improvement.

Description

Calibration device for contact on-line detection system of lathe

technical field

The utility model relates to the technical field of numerical control equipment, in particular to a calibration device for a contact-type online detection system of a lathe.

Background technique

In order to improve the positioning accuracy and processing efficiency of the positioning reference before the process, the online detection technology of the trigger probe has been widely used in the CNC machining process.

However, the principle of the trigger probe is to rely on the trigger force generated by the contact between the measuring ball and the workpiece to overcome the preload of the internal spring, thereby breaking the closed circuit inside the probe and finally sending out a trigger signal. In this way, after the measuring ball touches the workpiece to be measured, it needs a small displacement to stop. This displacement is called pre-travel error. Therefore, it is necessary to calibrate the probe before measuring to compensate for its pre-travel error. In addition, because the two-axis CNC lathe lacks a degree of freedom of movement, the installation error generated in the direction of the missing degree of freedom of movement cannot be eliminated by traditional calibration methods.

At present, the traditional devices used for probe calibration include standard balls and ring gauges. Calibration method: Adjust the measuring ball until it can collide with the largest outer circle of the calibration device, record the measured value displayed at this time, and compare it with the factory size of the calibration device to obtain the pre-travel error. However, on a two-axis CNC lathe, on the one hand, standard balls or ring gauges have the disadvantage of inconvenient clamping; on the other hand, even if the clamping is successful, the lathe lacks a degree of freedom of movement, resulting in tool setting on the probe. During calibration, the measuring ball may not necessarily be able to collide with the largest outer circle of the calibration device, resulting in inaccurate calibration.

In order to correct the installation error in the direction of the lathe’s lack of freedom of movement, the following measures are commonly used: 1. Measure the distance from the guide rail to the center of rotation of the spindle with a measuring tool such as a ruler or a caliper, and adjust the number and thickness of the shims according to this distance, so that the measured The center of the measuring ball of the head system is equal to the center of rotation of the spindle; 2. Using a fixed height ruler, the thickness of the head system that needs to be raised can be calculated according to the number of grids displayed by the ruler. But in the process of using a trigger probe, neither of these methods is applicable. The accuracy of the former is not enough, it is only a rough method, and it is not suitable for accurately adjusting the installation error in the direction of the lathe’s lack of freedom of movement; the actual measurement object of the latter is the tool tip, which is equivalent to the ball center of the trigger probe , and cannot be directly measured. Application No. 201210352231.X discloses a method for measuring cross-sectional dimensions of revolving body parts, which involves the correction of installation errors in the direction of the lathe’s lack of freedom of movement: first, use a micrometer to measure the precise radius at two different radius sections of the revolving body; then Use the lathe probe to calibrate the radius at one of the sections, and measure the measured value of the radius at the other section, and then obtain the error between the measured value and the actual value at the other section; finally, use the error and the two radius sections The precise radius at , and the deviation error of the center of the measuring ball is calculated. However, this method can only calculate the radial component of the installation error in the direction of the lathe’s lack of freedom of movement, and cannot calculate all the installation errors in the direction of the movement degree of freedom, nor can it calibrate the pre-travel error of the probe.

Utility model content

Aiming at the deficiencies of the prior art, the technical problem to be solved by the utility model is to provide a calibration device for a contact-type online detection system of a lathe.

The technical solution of the utility model to solve the technical problem of the calibration device is to provide a calibration device for a contact-type online detection system of a lathe, which is characterized in that the calibration device includes a clamping shaft and an L-shaped device main body; the clamp The holding shaft is a cylinder, one end of which is used for lathe chuck clamping, and the other end is connected with the top end of the long side of the L-shaped device main body, and the central axis of the clamping shaft is collinear with the center line of the long side of the L-shaped device main body; The bottom end of the L-shaped device main body has a stepped hole and a first hole; the central axis of the first hole, the central axis of the clamping shaft and the center line of the long side of the L-shaped device main body are collinear and are all in line with the rotation of the lathe spindle The center coincides; the stepped hole is composed of a through hole at the top and a second hole at the bottom; the central axis of the through hole and the central axis of the second hole are collinear and parallel to the center of rotation of the lathe spindle; the first hole and the through hole The connecting line of the hole center of the hole is parallel to the transverse feed direction of the lathe; the central axis of the through hole is parallel to the central axis of the first hole; the radius of the first hole and the through hole are the same.

Compared with the prior art, the utility model has the beneficial effects of:

1. The calibration device has been improved on the basis of traditional ring gauges and standard balls. It is suitable for the contact online detection system of two-axis horizontal CNC lathes. The structure has been improved as follows:

(1) Design a stepped hole (consisting of a through hole and a second hole), the first hole and a distance, the purpose of which is to increase the known size of the calibration device, so that according to the complex geometric relationship between the measured value and the known value , to solve for the error. However, the existing ring gauges and standard balls only contain a known size, so it is impossible to accurately calibrate the X+ direction pre-travel error on the two-axis CNC lathe, and it is impossible to calibrate the installation error in the direction of the lathe’s lack of freedom of movement.

(2) The main body of the L-shaped device is designed as a plane, while the outer contours of traditional ring gauges and standard balls are arc-shaped, which is not convenient for storage.

(3) Designing the main body of the L-shaped device instead of a square body can reduce the occupied space, save materials, and avoid possible interference at the same time.

(4) The cylindrical clamping shaft is designed to facilitate the clamping of the three-jaw chuck of the lathe, which solves the problem of inconvenient installation of the traditional calibration device on the two-axis CNC lathe. However, when the traditional ring gauge is installed on the lathe, the smoothness of the outer surface will be damaged. When the traditional standard ball is installed on the lathe, the magnetic base must be borrowed, which increases the cost.

2. The traditional ring gauge only contains a hole where the installed axis coincides with the center of rotation of the spindle of the CNC lathe. During calibration, only one equation can be constructed, which contains two unknown errors, which obviously cannot meet the calibration requirements. The utility model adds a stepped hole to the structural form of the original ring gauge. According to the known hole diameter value, the measurement value of the probe to the hole, and the geometric relationship between a stepped hole and the first hole, construct and solve the equation including the pre-travel error and the installation error in the direction of the lathe’s lack of freedom of movement, In this way, the X+ pre-travel error of the probe and the installation error in the direction of the lathe's missing movement degree of freedom are obtained.

Description of drawings

Fig. 1 is the axonometric schematic diagram of the calibration device of a kind of embodiment of the calibration device of the contact type on-line detection system of the utility model for lathe;

Fig. 2 is a calibration route diagram of an embodiment of the calibration device of the contact type online detection system used in lathes according to the present invention;

Fig. 3 is the calibration schematic diagram of the calibration device of an embodiment of the calibration device used in the contact type online detection system of the lathe; (1, clamping shaft; 2, L-shaped device main body; 21, L-shaped device main body length side; 22, the short side of the main body of the L-shaped device; 3, the through hole; 4, the second hole; 5, the first hole)

Detailed ways

Provide the specific embodiment of the present utility model below. The specific embodiments are only used to further describe the utility model in detail, and do not limit the protection scope of the claims of the present application.

The utility model provides a calibration device (referred to as the calibration device) for a contact-type online detection system of a lathe, which is characterized in that the calibration device is integrally processed from a piece of material, including a clamping shaft 1 and an L-shaped device main body 2 ; The clamping shaft 1 is a cylinder, one end of which is used for lathe chuck clamping, fixed on the three-jaw chuck of the lathe, and the other end is connected with the top end of the long side 21 of the L-shaped device main body, and the clamping shaft 1 The central axis is collinear with the center line of the long side 21 of the L-shaped device main body; the bottom end of the L-shaped device main body 2 has a stepped hole and a first hole 5; the central axis of the first hole 5, the clamping shaft 1 The central axis of the center axis and the centerline of the long side 21 of the L-shaped device main body are collinear and coincide with the center of rotation (ie, the Z direction) of the lathe spindle; Composition; the central axis of the through hole 3 and the central axis of the second hole 4 are collinear and parallel to the center of rotation (i.e. Z direction) of the lathe spindle; the connecting line of the hole center of the first hole 5 and the through hole 3 is parallel to the lathe Transverse feed direction (i.e. X direction); the central axis of the through hole 3 is parallel to the central axis of the first hole 5 and the center-to-center distance is half of the bottom end length of the L-shaped device main body 2; the first hole 5 and the through hole 3 of the same radius.

The working principle and working process of the calibration device of the utility model for the contact type on-line detection system of the lathe are: the machine tool coordinate system of the lathe is based on the origin O of the machine tool as the origin of the coordinate system, and follows the right-hand Cartesian rectangular coordinate system established by X, Cartesian coordinate system composed of Y and Z axes; in the lathe machine tool coordinate system, the X-axis direction is horizontally along the radial direction of the workpiece, and the Z-axis is horizontally along the lathe spindle direction, and the X-axis and Z-axis are both positive so that the workpiece is far away from the tool , the missing Y-axis is determined according to the right-hand Cartesian coordinate system, and is positive vertically downward; it is characterized in that the calibration method includes the following steps:

Step 1. Install the calibration device on the lathe, wherein the central axis of the first hole 5, the central axis of the clamping shaft 1, and the centerline of the long side 21 of the L-shaped device body are collinear and are all aligned with the rotation center of the lathe spindle (i.e. Z direction) coincides; the central axis of the through hole 3 and the central axis of the second hole 4 are collinear and parallel to the center of rotation of the lathe main shaft; The given direction (that is, the X direction); the clamping axis 1 is fixed on the three-jaw chuck of the lathe, and the probe of the trigger-type online detection system is installed under a certain tool number on the tool table; the first hole 5 and the through hole 3 The hole center distance is a known value 2a, the radius of the first hole 5 and the through hole 3 is a known value R, and the radius of the second hole 4 is a known value r (r<R);

Step 2. Under this tool number, perform preliminary probe calibration through the first hole 5 to establish a workpiece coordinate system with pre-travel error, and the origin of the workpiece coordinate system is O ₂ ';

Step 3. The measuring head moves along the path S1 from the initial height, and positions the measuring ball to the origin O ₂ ' of the workpiece coordinate system; the measuring head measures the theoretical measuring point A ₂ along the path S2; A ₂ is located on the first hole 5, close to the second hole On one side of 4, the distance from A ₂ to the bottom surface of the main body 2 of the L-shaped device is greater than the diameter of the measuring ball and less than the length of the measuring rod; after the measurement of the theoretical measuring point A ₂ is completed, the measuring head returns to the origin of the workpiece coordinate system O ₂ ' along the path S3 ; The theoretical measuring point on the first hole 5 is A ₂ , but the actual measuring point is A ₂ ', and the pre-travel error is obtained, that is, the displacement between the theoretical measuring point A ₂ and the actual measuring point A ₂ ';

Step 4. The probe passes through the path S4 to S6, and the moving distance of the probe in the X direction is 2a, that is, the probe ball is positioned at the center of the through hole 3; use the probe to measure the radius of the through hole 3, that is, the probe moves along the path S7 Measure the fixed point B ₂ on the through hole 3; B ₂ is located on the through hole 3, near the side of the first hole 5, and the distance from B ₂ to the bottom surface of the L-shaped device main body 2 is greater than the diameter of the measuring ball and less than the length of the measuring rod; The existence of pre-travel error, the actual measured value is the coordinate of point B ₂ '; let m=O ₂ 'B ₂ ';

Step 5: After the probe returns along the path S8, the measuring ball is positioned at the center of the second hole 4 through the path S9; use the probe to measure the radius of the second hole 4, that is, the probe measures the radius of the second hole 4 along the path S10 Fixed point B ₃ ; B ₃ is located on the second hole 4, near the side of the first hole 5, the distance from B ₃ to the bottom surface of the L-shaped device body 2 is the depth of the through hole 3 and the bottom surface of the B ₂ to the L-shaped device body 2 The sum of the distance; due to the existence of the pre-travel error, the actual measured value is the B ₃ ' point coordinate; let n=O ₂ 'B ₃ ';

Step 6. The probe returns to the center of the second hole 4 along the path S11, and then rises to the initial height along S12 to complete the entire measurement process;

Step 7. Combining the known quantities R, r, and a, obtain the pre-travel error δ and Y-direction installation error y according to the following formula:

Step 8. Correct the installation error in the Y direction: if y=0, it means that there is no installation error in the Y direction; if |y|<H ₀ , H ₀ is the thickness of a gasket (when the probe is installed on the tool holder, the gasket Pad between the tool holder and the probe, by adjusting the thickness between the tool holder and the probe, the position of the probe can be adjusted), then adjust the top wire of the tool handle used to clamp the probe; if |y|≥ H ₀ , first adjust the number and thickness of the shims for rough adjustment, and then use the top screw for fine adjustment;

Step 9. After adjustment, repeat steps 1-8 until y=0;

Step 10. Record the δ value when y=0, which is the X+ pre-travel error of the probe; write δ into the probe measurement macro program for compensation of the measured value of the workpiece to be measured.

The derivation process of Equation 10 and Equation 11 is as follows: the center of the measuring ball is projected to the XOY plane to become a point, the projection of the calibration device on the XOY plane is the first hole 5, the through hole 3 and the second hole 4, and the three-dimensional spatial relationship is transformed Into a two-dimensional graphic representation, where A ₁ , A ₁ ', O ₁ , O ₁ ', B ₁ and B ₁ ' are collinear in the XOY plane and parallel to the X direction; O ₂ ', A ₂ , A ₂ ' , B ₂ ', B ₂ , B ₃ ' and B ₃ are collinear in the XOY plane and parallel to the X direction;

(1) If there is no installation error in the Y direction, in the workpiece coordinate system, due to the existence of the pre-travel error, the origin of the workpiece coordinate system is O ₁ ', not the center O ₁ of the first hole 5, then the X coordinate of point A ₁ The measurement value is O ₁ 'A ₁ ', and the X coordinate measurement value of point B ₁ is O ₁ 'B ₁ '. Since the probe has high repeatability, the pre-travel error δ generated each time is equal, that is, A ₁ A ₁ '=B ₁ B ₁ '=δ; at the same time, according to the rules of lathe system construction, O ₁ 'A ₁ '=O ₁ A ₁ =R, O ₁ A ₁ '=O ₁ A ₁ +A ₁ A ₁ '=R+δ;

(2) When there is an installation error y (0≤y<R) on the Y axis, the theoretical measuring points are A ₂ , B ₂ and B ₃ , and the actual measuring points are A ₂ ', B ₂ ' and B ₃ ', the origin of the established workpiece coordinate system is O ₂ '; first, when the measuring ball collides with the three holes of the calibration device, the contact force is all along the radial direction of the shaft section, so the pre-travel errors generated are not only the same in size but also along the The shaft section is radial, so A ₂ and A ₂ ' are both on the circle with the center O ₁ of the first hole 5 as the center and R+δ as the radius, and B ₂ and B ₂ ' are both in the center O of the through hole 3 ₂ is the center of the circle with R+δ as the radius, B ₃ and B ₃ ' are both on the circle with the center of the second hole 4 O ₂ as the center of the circle and r+δ as the radius; secondly, according to the rules of lathe system construction , O ₂ 'A ₂ '=O ₁ 'A ₁ '=R; formula 1 and formula 2 are obtained from the above relationship:

O ₂ 'B ₂ '=O ₂ 'A ₂ '+A ₂ 'B ₂ ' (1)

O ₂ 'B ₃ '=O ₂ 'A ₂ '+A ₂ 'B ₃ ' (2)

(3) In the physical coordinate system, set the coordinates of point O ₁ as (a, 0), and the coordinates of point O ₂ as (-a, 0), and the equation of the circle where A ₂ 'is located is Equation 3, and the equation of B ₂ ' is For formula 4:

(xa) ² +y ² = (R+δ) ² (3)

(x+a) ² +y ² ＝(R+δ) ² (4) Simultaneous formula 3 and formula 4 can get formula 5:

(4) Substituting Equation 5 into Equation 1, Equation 6 can be obtained:

Among them, O ₂ 'B ₂ ' is the measured value, R and a are known values;

(5) Similarly, the equation of B ₃ ' is formula 7:

(x+a) ² +y ² ＝(r+δ) ² (7) Simultaneous formula 3 and formula 7 can get formula 8:

Substituting Equation 8 into Equation 2, Equation 9 can be obtained:

(6) Arrange formula 6 and formula 9, set m=O ₂ 'B ₂ ', n=O ₂ 'B ₃ ', then the pre-travel error δ can be obtained as shown in formula 10, and the Y-direction installation error y is shown in formula 11 Shown:

The lathe using this calibration device is preferably CK6136S two-axis horizontal CNC lathe. The probe includes a probe ball, a probe rod, etc.; the probe ball is the part of the probe responsible for contact. The unmentioned part of the utility model is applicable to the prior art.

Claims (2)

1. A calibration device for a contact-type on-line detection system of a lathe, characterized in that the calibration device includes a clamping shaft and an L-shaped device main body; the clamping shaft is a cylinder, and one end thereof is used for lathe chuck loading clamp, the other end is connected to the top end of the long side of the L-shaped device body, the central axis of the clamping shaft is collinear with the center line of the long side of the L-shaped device body; the bottom end of the L-shaped device body has a stepped hole and a first Holes; the central axis of the first hole, the central axis of the clamping shaft, and the center line of the long side of the L-shaped device body are collinear and coincide with the center of rotation of the lathe spindle; the stepped hole is composed of the through hole at the top and The second hole located below constitutes; the central axis of the through hole and the central axis of the second hole are collinear and parallel to the center of rotation of the lathe spindle; the line connecting the center of the first hole and the through hole is parallel to the lateral feed of the lathe direction; the central axis of the through hole is parallel to the central axis of the first hole; the radius of the first hole and the through hole are the same. 2. The calibration device for a contact-type on-line detection system for a lathe according to claim 1, wherein the center-to-center distance between the through hole and the first hole is half the length of the bottom end of the L-shaped device main body.