CN104259933A - Ball nut phase measuring device and corresponding nut reverser hole processing method - Google Patents

Abstract

The invention discloses a ball nut phase measuring device. In the machining of the hole of the reverser, the device can be used for detecting the phase angle and the axial position of the thread raceway, so that the position degree of the thread raceway and the hole of the reverser is ensured. The main structure includes: the device comprises a connecting shaft 1, a linear guide rail 2, a sliding block 3, a connecting plate 4, a pressing plate 5, a measuring rod 6, a spherical measuring head 7, a supporting block 8, a connecting block 9, a spring 10, a meter frame 11 and a dial indicator 12. The positions of the connecting shaft 1, the guide rail 2, the supporting block 8 and the connecting block 9 are fixed. The slide block 3, the connecting plate 4, the pressing plate 5, the measuring rod 6 and the measuring head 7 are fixed in position, and the parts form a whole capable of moving along the direction of the guide rail. The invention also discloses a process method for machining the nut reverser hole by matching the ball nut phase measuring device with the vertical machining center, wherein the process method comprises an inner circulation nut and an outer circulation nut.

Description

Ball nut phase measuring device and corresponding nut reverser hole processing method

technical field

The invention relates to a phase measuring device for a ball nut thread raceway. In the processing of the ball nut reverser hole, the processing position of the reverser hole can be determined by detecting the phase angle and axial position of the thread raceway, so as to ensure the positional accuracy of the thread raceway and the reverser hole. This device is suitable for phase measurement of inner circulation, outer circulation and end surface circulation nut thread raceway.

Background technique

The ball screw pair is a transmission part that uses the ball as the rolling body between the screw and the nut. The screw rotates and drives the nut to make a linear motion through the ball, or the nut linear motion drives the screw to rotate through the ball. The ball screw pair can not only transmit power, but also realize precise positioning in the linear direction. Therefore, ball screw pairs are widely used in CNC machine tools, industrial robots and other equipment.

As shown in FIG. 10 , the ball screw pair includes main parts such as a ball screw 101 , a ball nut 102 , and a reverser 103 . Among them, the ball nut is the most complicated part in the ball screw pair, and it is also the part that has the greatest impact on the performance of the ball screw pair such as noise and temperature rise.

As shown in Figure 11, the ball nut has a threaded raceway 201 and a reverser hole 202, and the two centerlines of the reverser hole and the pitch circle intersection (203) must meet the following conditions: First, along the direction of the nut axis to the screw The distance between the adjacent points on the line is half of the lead; second, after rotating 180° around the axis of the nut, it is just on the helix. Only when the retroverter hole meets the above conditions, after the retroverter is installed on the nut, the interface between the ball return groove and the threaded raceway is correct, as shown in Figure 12. In Fig. 12, 301 is a nut, and 302 is a reverser.

For a long time, the ball nut adopts the process method of milling the reverser hole first and then turning the threaded raceway. During the turning process of the ball thread, the worker adjusts the starting point of the turning thread, that is, the initial phase angle of the thread, according to the visual value of the position of the reverser hole and the thread raceway. This method not only has a large error, but also the processing of turning thread is intermittent cutting, the efficiency is low, and the tool is easy to break.

The excessive error between the ball thread and the hole of the return device directly leads to an excessively large step at the interface between the ball return groove of the return device and the thread raceway after assembly. During operation, when the balls pass through here, there will be large noise and torque fluctuation due to collision. At present, this problem has become the main factor restricting the performance improvement of the ball screw pair.

Contents of the invention

The purpose of the present invention is to provide a ball nut thread raceway phase measurement device with simple structure, convenient operation, and accurate determination of the position of the reverser hole on the ball nut, so as to improve the processing efficiency and overcome the shortcomings of the prior art.

The main mechanical structure of the ball nut thread raceway phase measuring device of the present invention includes: a connecting shaft, a linear guide rail, a slider, a connecting plate, a pressing plate, a measuring rod, a spherical measuring head, a supporting block, a connecting block, a spring, a table frame, a hundred Sub-meter; the relative positions of connecting shaft, guide rail, support block and connecting block are fixed; The whole of the movement.

The spring keeps the movable part downward; during measurement, under the action of spring tension, the spherical probe is always in contact with the edge of the raceway; when not measuring, under the action of spring force, the connecting plate and the support block touch.

The meter frame and the dial indicator are connected together by screws, and there is a long waist-shaped groove on the meter frame, which can be used to adjust the position of the meter frame along the direction of the guide rail; during the measurement, according to the depth of the measured thread raceway, it needs to be adjusted. The meter frame, the adjustment requirement is to make the dial indicator within its range.

The method for detecting the phase of the reverser hole of the internal circulation nut in the thread raceway by using the ball nut thread raceway phase measuring device, the steps are as follows:

a) Install the phase measurement device on the spindle of the vertical machining center;

b) Install the nut on the A-axis chuck of the vertical machining center;

c) Adjust the position of the probe so that the probe coincides with the center of the nut on the Y axis of the machine tool. The probe is located at the center of the reverser hole on the X axis. downward movement trend;

d) Rotate the A-axis of the machine tool and observe the value of the dial indicator. When the value of the dial indicator is the largest, the position opposite the probe is the center of the reverser hole.

The method for detecting the phase of the guide ball tube hole of the outer circulation nut in the thread raceway by using a ball nut thread raceway phase measuring device is characterized in that the steps are as follows:

a) Install the phase measurement device on the spindle of the vertical machining center;

b) Install the nut on the A-axis chuck of the vertical machining center;

c) Adjust the position of the probe so that the probe coincides with the center of the nut on the Y axis of the machine tool;

d) The position of the measuring head on the X-axis, that is, the distance L from the center of the measuring head in the direction of the nut axis to the right end surface is calculated in two cases. First, when the number of loops of the guide ball tube is 1.5 or 3.5, L is as follows Mode:

Second, when the number of loops of the guide bead tube is 2.5, L is as follows:

In the above formula, the values of A and B are shown in Figure 9, Ph is the lead of the ball screw pair, n is an integer (n=0, ±1, ±2, ±3,...), the value of n can be determined according to the measuring rod The length that extends into the nut is determined;

e) The probe moves one end distance in the Z-axis direction, so that the probe still has a downward trend when it is in the bottom ditch;

f) Rotate the A-axis of the machine tool and observe the value of the dial indicator. When the value of the dial indicator is the largest, the position opposite the probe is the machining position of the outer circle of the nut.

The measuring device of the present invention has a simple overall structure and is easy to operate. It can determine the position of the reverser hole more accurately, further improves the positional degree of the ball nut thread raceway and the reverser hole, and improves the processing efficiency of the nut.

Description of drawings

Fig. 1 is a front view of a phase measuring device.

Fig. 2 is a left side view of the phase measuring device Fig. 1 .

Fig. 3 is the ball nut of the reverser hole to be processed.

Fig. 4 is a schematic diagram of the application of the phase measuring device.

Fig. 5 is a schematic diagram of the position of the ball nut deflector hole.

Figure 6 is a diagram of the relative position relationship between the probe and the raceway of the phase measurement device, a is a schematic diagram of the probe on the left side of the raceway, b is a schematic diagram of the probe located at the center of the raceway, and c is a schematic diagram of the probe located on the right side of the raceway Schematic,.

Fig. 7 is a schematic diagram of the table frame.

Fig. 8 is a sectional view of the outer circulation nut.

FIG. 9 is a top view of FIG. 8 .

Figure 10 is a schematic diagram of a ball screw pair.

Fig. 11 is a sectional view of a ball nut.

Fig. 12 is a sectional view of the reverser installed in the nut.

Detailed ways

The specific implementation of the device of the present invention will be described below in conjunction with the accompanying drawings.

The connecting shaft of the device of the present invention is shown as 1 in Fig. 1. The upper cylindrical part of the shaft is used to connect with the main shaft tool handle, and the lower end is connected with the guide rail. Since it needs to be disassembled regularly, and the cylindrical part will be subjected to a larger clamping force, Therefore, the connecting shaft is made of high-quality low-carbon alloy structural steel, which has been carburized and quenched. Therefore, the mounting part of the connecting shaft has the characteristics of toughness on the inside and hardening on the outside.

Part No. 2 in Figure 1 is a high-precision rolling linear guide pair, which has the advantages of high precision and low friction. Because it is used for measurement, the load on the guide rail pair is very small, and the movement between the slider and the guide rail is required to be flexible during the measurement process, so the guide rail pair should use a small preload. The guide rail is fixed on the connecting shaft with the screw on the front and the pressure plate on the side. Three threaded holes are processed at the lower end of the guide rail, and the indicator frame 11 and the guide rail are fixed together by bolts. There are threaded holes for installation on the slider 3, and the threaded holes are used to fix the connecting plate 4. When fixing the connecting plate, its right side must be in contact with the reference side of the slider 3, and the middle large plane must be in contact with the upper top surface of the slider. Contact, and the side should be tightened with jackscrew to ensure that the reference side of the slider is in contact with the right side of the connecting plate.

The function of the measuring rod is to transmit the displacement transmitted by the measuring head 7 to the dial indicator through the connecting plate 4 and the slider 3. In order to reduce the error in this link, the measuring rod needs a high rigidity, so high carbon chrome is selected Alloy steel, and adopts advanced quenching treatment to make its hardness reach above HRC64. At the same time, the total length of the measuring rod should be as short as possible under the condition of meeting the measuring range.

The measuring head 7 is in contact with the nut raceway or the inner wall during the measurement process. As the nut rotates, the positional relationship of the measuring head relative to the rolling is shown in Figure 6. There is sliding friction between the probe and the raceway, and the probe must have sufficient hardness and wear resistance, so the material of the probe is selected from carbide with better wear resistance. The probe cannot be loose during installation, and the screw on the right side must be tightened. When measuring, in order to avoid the error caused by the crawling of the probe, a proper amount of lubricating oil should be applied to the probe.

The connecting block 9 is used to install the supporting block 8, the spring 10 and the watch frame 11, and the connecting block is in a static state during the whole measurement process. The connection block is made of ordinary medium-carbon high-quality structural steel, which is processed after quenching and tempering. A support block 8 of nylon material is installed on the right side of the connection block, and the support block is fixed on the connection block with two screws. The function of the support block is to support the slider. When not working, the slider has a tendency to move downward under the action of gravity and spring tension. Without the flexible support of the support block, the slider and its movable parts may damage the dial indicator.

The effect of the spring 10 is to pull the slider and its movable part downwards. During the measurement process, the probe needs to have a continuous downward movement trend, so that the processing position of the reverser hole can be found from the change process of the dial gauge during the process of rotating the nut.

The dial indicator 12 is fixed together with the table frame 11 by screws. The watch frame 11 is made of carbon structural steel after quenching and tempering treatment. A long waist-shaped groove is arranged on the watch frame 11, as shown in Figure 7 . The relative position of the meter frame and the connection block can be adjusted, that is, the position of the dial indicator can be adjusted along the direction of the linear guide rail.

The size of the spherical probe is consistent with the tooth shape of the raceway, that is, the size of the probe is the same as that of the balls used in the ball screw pair.

This measuring device can be installed on the spindle of a machining center or a turning-milling compound center. Take a vertical machining center with an A-axis as an example for illustration. Z position. First of all, the probe needs to be adjusted to the center plane of the nut along the direction perpendicular to the axis of the nut, that is, the Y direction of the machine tool. Secondly, it is necessary to move the spherical probe along the direction of the nut axis, that is, the X direction of the machine tool, to the position A shown in Figure 5. Then move the measuring head along the Z axis for a certain distance. The moving distance should make the measuring head touch the bottom groove of the raceway. Under the action of the spring force, the measuring head still has a tendency to move downward. Then adjust the A axis of the machine tool, that is, the nut rotation axis, and observe the change of the dial indicator. During this process, the position change of the probe in the raceway is shown in Figure 6. The value of the dial indicator will change from small to large, and then from large to small, and so on. When the dial indicator shows the maximum value, the measuring head is in the middle position in the raceway, as shown in Figure 6. At this time, the position of the 180-degree nut of the measuring head is the center of the reverser hole, and then the reverser hole can be processed according to this position.

The position opposite to the center of the returner hole of the inner circulation nut is exactly the center position of the thread raceway, so when measuring, the position of the probe in the axial direction of the nut should be consistent with A in Figure 5.

The device of the present invention can also be applied to external circulation nuts. After finishing the outer circle, inner hole, end face and thread raceway of the outer circle nut, the device of the present invention can be used to measure the position of the outer circle plane, as shown in Figure 8. After the plane processing is completed, the guide bead tube hole can be processed. A schematic diagram of the bead guide is shown in FIG. 9 , which is a top view of FIG. 8 .

For the outer circulation nut, the distance L from the center of the probe to the right end face in the direction of the nut axis can be determined in the following two ways:

First, when the number of loops of the guide bead tube is 1.5 or 3.5, L is as follows:

Second, when the number of loops of the guide bead tube is 2.5, L is as follows:

In the above formula, the values of A and B are shown in Figure 9, Ph is the lead of the ball screw pair, n is an integer (n=0, ±1, ±2, ±3, ...), the value _of n can be measured according to The length of the rod protruding into the nut is determined.

The present invention is further described below:

The ball nut phase measuring device provided by the present invention is shown in FIG. 1 . In Fig. 1, 1 is a connecting shaft, and the upper cylindrical part of the connecting shaft can be installed on the main shaft of a machining center or a turning-milling compound center through a tool handle. 2 is a linear guide rail, and the guide rail is fixed on the 1 connecting shaft by screws. 3 is a slide block, which can move up and down along the guide rail direction on the guide rail 2. 4 is connecting plate, and connecting plate is fixed on the slide block. 5 is a pressing plate, which is used to fix the measuring rod 6. 7 is a spherical measuring head, and the size of the measuring head is consistent with the ball of the screw pair. 8 is a support block, which is used to support the slide block and the whole movable part in a non-working state. 9 is a connecting block, which is used to install the support block 8, the spring 10 and the watch frame 11. 12 is a dial indicator, which is used to detect the change of the spherical probe 7 in the vertical direction.

The relative positions of the connecting shaft 1, the guide rail 2, the supporting block 8 and the connecting block 9 are fixed. The relative positions of the slider 3, the connecting plate 4, the pressing plate 5, the measuring rod 6, and the measuring head 7 are fixed, and at the same time, these parts form a whole that can move along the direction of the guide rail.

The spring 10 maintains a tension that pushes the movable part downwards. During measurement, under the action of spring tension, the spherical probe is always in contact with the edge of the raceway. When not measuring, the connecting plate 4 is in contact with the supporting block 8 under the action of the spring force. The two ends of the spring 10 are respectively fixed with the connecting plate 4 and the connecting block 9 by screws.

The meter frame 11 and the dial indicator 12 are connected together by screws, and there is a long waist-shaped groove on the meter frame, which can be used to adjust the position of the meter frame along the direction of the guide rail, as shown in Figure 2. During the measurement, according to the depth of the measured thread raceway, the meter frame needs to be adjusted, and the adjustment requirement is to make the dial gauge 12 within its range.

In the processing of ball nuts, when the device of the present invention is applied, the threaded raceway 13 must be processed first, as shown in Figure 3, and then the processing position of the reverser hole needs to be found. As shown in Figure 4, in order to ensure the exact position of the reverser hole and the thread raceway, the phase of the thread raceway must be measured with the device of the present invention. Before the measurement, the device of the present invention needs to be installed on the main shaft of the machining center through the tool handle 14. Here, a four-axis vertical machining center is taken as an example for illustration. When installing, it is necessary to keep the measuring rod of the device of the present invention parallel to the axis of the nut. The nut 15 is installed on the chuck 16 of the A axis of the machine tool. After the device of the present invention is installed, it is necessary to adjust the Y-axis coordinates of the machine tool so that the spherical center of the measuring head is in the XOZ plane passing through the nut axis. Then perform tool setting on the X coordinate of the measuring head, and the tool setting position should be consistent with the milling cutter milling the hole of the reverser, so as to eliminate the error caused by the unevenness of the benchmark.

When measuring, as shown in Figure 4, the X coordinate of the spherical probe needs to be moved to the A position in Figure 5, and the A dimension is the distance from the reverser hole to the nut end face. If the end face of size A requires subsequent finishing, the end face finishing allowance must be added when moving the probe.

After the Y axis moves in place, the Z axis of the machining center needs to be adjusted. First, it is necessary to visually measure the distance from the spherical probe to the bottom groove of the nut raceway, and then move the Z-axis of the machining center. The absolute value of the moving distance increment should be greater than the distance from the previous visual measurement probe to the bottom groove. During this process the probe touches the bore of the nut, possibly somewhere in the raceway.

After the above steps are completed, manually and slowly adjust the A axis of the machining center, that is, the central axis of the nut, to make the nut rotate slowly. At the same time, observe the change of the dial indicator. As the nut rotates, the change of the positional relationship between the probe and the raceway in the XZ plane is shown in Figure 6. During the rotation of the nut, the measuring head moves up and down accordingly, and the movement of the measuring head will bring about the movement of the measuring rod in the device of the present invention. Since the measuring rod is fixed on the slider through the connecting plate, it will drive the sliding block to move up and down. The change in the amount of movement will be displayed on the dial indicator. When the probe moves to the middle position in Figure 6, which is the lowest point in the Z-axis direction, the value on the dial indicator will also change to the maximum value. At this time, the position of the nut in the circumferential direction is the position of the center of the machining return hole. .

Claims (5)

1. A ball nut thread raceway phase measurement device, characterized in that the main mechanical structure includes: connecting shaft (1), linear guide rail (2), slider (3), connecting plate (4), pressing plate (5) , measuring rod (6), spherical measuring head (7), support block (8), connecting block (9), spring (10), meter frame (11), dial indicator (12); connecting shaft (1), The relative positions of guide rail (2), support block (8) and connection block (9) are fixed; The relative position is fixed, and at the same time, this part forms a whole that can move along the direction of the guide rail. 2. The ball nut thread raceway phase measurement device according to claim 1, characterized in that: the spring (10) maintains a pulling force to push the movable part downward; during measurement, under the action of spring tension, the spherical measuring The head is always in contact with the edge of the threaded raceway; when not measuring, the connecting plate (4) is in contact with the support block (8) under the action of the spring force. 3. The ball nut thread raceway phase measurement device according to claim 2, characterized in that: the meter frame (11) and the dial indicator (12) are connected together by screws, and there are long The waist-shaped groove can be used for adjusting the position of the meter frame along the direction of the guide rail; during the measurement, according to the depth of the measured thread raceway, the meter frame needs to be adjusted, and the adjustment requirement is to make the dial indicator (12) within its range. 4. A method of utilizing the ball nut thread raceway phase measuring device as claimed in claim 1 or 2 or 3 to detect the phase of the reverser hole of the inner circulation nut in the thread raceway, characterized in that: the steps are as follows: Install the phase measurement device on the spindle of the vertical machining center; Install the nut on the A-axis chuck of the vertical machining center; Adjust the position of the probe so that the probe coincides with the center of the nut on the Y axis of the machine tool, and the probe is located at the center of the reverser hole on the X axis. downward moving trend; Rotate the A-axis of the machine tool and observe the value of the dial indicator. When the value of the dial indicator is the largest, the position of the outer circle of the nut opposite the probe is the center of the reverser hole. 5. A method of utilizing the ball nut thread raceway phase measuring device as claimed in claim 1 or 2 or 3 to detect the phase of the guide ball hole of the outer circulation nut in the thread raceway, characterized in that: the steps are as follows: a) Install the phase measurement device on the spindle of the vertical machining center; b) Install the nut on the A-axis chuck of the vertical machining center; c) Adjust the position of the probe so that the probe coincides with the center of the nut on the Y axis of the machine tool; d) The position of the measuring head on the X-axis, that is, the distance L from the center of the measuring head in the direction of the nut axis to the right end surface is calculated in two cases. First, when the number of loops of the ball guide tube is 1.5 or 3.5, L is as follows Mode: Second, when the number of loops of the guide bead tube is 2.5, L is as follows: In the above formula, the values of A and B are shown in Figure 9, Ph is the lead of the ball screw pair, n is an integer (n=0, ±1, ±2, ±3,...), the value of n can be determined according to the measuring rod The length that extends into the nut is determined; e) The probe moves one end distance in the Z-axis direction, so that the probe still has a downward trend when it is located in the bottom ditch; f) Rotate the A-axis of the machine tool and observe the value of the dial indicator. When the value of the dial indicator is the largest, the position opposite the probe is the machining position of the outer circle of the nut.