JPH0547737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a feed screw device and a method for recording scales on the screw shaft thereof, and in particular records information including scales on the outer circumferential surface of the screw shaft of a feed screw, and The present invention relates to a feed screw device and a scale recording method thereof, which are compact and easy to handle by providing information reading means in the nut, and which can appropriately provide necessary information to an operator.

Prior Art A feed screw device is in practical use as one of the mechanical elements that converts rotational motion of a motor etc. into linear motion, but conventionally known feed screw devices simply convert rotational motion into linear motion. In order to move the linearly moving object while controlling its position, the screw shaft must be rotated using a servo motor, and the amount of movement must be detected by a position detection sensor and feedback control must be performed. It didn't happen.
As a sensor, for example, an encoder is attached to one end of the screw shaft to detect the rotation angle of the screw shaft, and the moving distance is calculated from the rotation angle and the pitch of the lead groove of the screw shaft, or a linear scale is installed parallel to the screw shaft. A sensor must be installed to detect the amount of movement of a moving object, and each detection sensor requires a dedicated installation location, resulting in a large device. In addition, the sensor simply outputs a signal every time it moves a certain distance, and other sensors, such as a limit switch, must be provided to determine the start or end point of the movement, which makes the device more compact. The disadvantage was that it was difficult to

As another example, it is known to use a stepping motor as the drive motor, but in this case, the stepping motor follows the drive signal from the control circuit in fixed angle increments (for example, 1.8° or 15°). Since it rotates, a position detection sensor is not required, but this also requires a sensor to detect the start point or end point of the movement, which increases the size of the device, and the installation position of the sensor is almost fixed, so there is less freedom in design. The drawback was that it was difficult to design optimally. Furthermore, the minimum rotation angle of a stepping motor is determined by the type of motor and the control circuit, making it difficult to achieve high resolution and making precise position control impossible. Furthermore, the cost of the motor itself is high, and a special drive control circuit is required, resulting in a very high cost. Furthermore, it has been difficult to provide appropriate work information to the worker in the form of audio or images.

In addition, Japanese Utility Model Publication No. 40-32286 discloses a semi-fixed variable resistor, but in this conventional example, a resistor is provided on the screw thread, and a movable section is provided on the nut to prevent the movement of the nut. The resistance value is changed continuously, and independent resistors are provided on both sides of the screw thread so that two changes in resistance value can be obtained at once. In order to measure the distance traveled by a nut based on the change, the measured value (resistance value) cannot be used as is; it must be converted into some kind of numerical value using a calculation method, and there is room for error in this conversion process. Also, since the resistance value is detected as an analog quantity as an integrated value from 0, it must be converted to a digital quantity, making it impossible to perform extremely accurate measurements. It is not possible to measure distance extremely accurately. That is, the invention of the prior art is a completely different invention in terms of purpose, structure, and effect from the present invention, which has a scale as a digital quantity on the outer circumferential surface of the screw shaft from the beginning.

Purpose The present invention was made in order to eliminate the drawbacks of the above-mentioned prior art, and its purpose is to provide a threaded shaft having a circular cross-section with a lead groove formed therein, and a threaded shaft having a circular cross-section formed with a lead groove. In a feed screw device consisting of a nut that moves in the axial direction of the screw shaft in synchronization with the rotation of the screw shaft, a digital scale and audio information are provided on the outer peripheral surface of the screw shaft along the lead groove. Or, by equipping the nut with a screw shaft that records information such as image information and a reading means to read the information, it is necessary to specially provide a sensor to detect the position and a sensor to detect the start and end points of the movement. It is to eliminate gender. Another object is to increase the degree of freedom in design by eliminating the need for the above-mentioned sensor, to enable optimal design, and to downsize the device. Still another object is to improve the accuracy of position detection and enable precise position control. Another purpose is to appropriately provide necessary information to workers through audio or visual information, improve work efficiency, and make it easier to perform error-free and safe work. . Still another purpose is to calculate the speed, acceleration, or force acting on a moving object moment by moment from the position information obtained by reading the scale recorded in high density and the time required for reading. hand,
The purpose is to enable highly accurate control.

Another purpose is to record a scale as a digital quantity on the outer circumferential surface of the screw shaft along the lead groove, so that even one screw thread can be as small as 3.14 mm in diameter of the screw shaft.
The goal is to secure an extremely long recordable length, which is actually several times the length of the screw thread. The goal is to be able to provide information.

Another purpose is to simply convert an analog quantity into a digital quantity by recording a digital quantity scale on the outer circumferential surface of the screw shaft and directly detecting and reading this with the reading means of the nut. The aim is not only to eliminate the possibility of reading errors but also to obtain extremely accurate reading accuracy.

Another purpose is to record scales as digital quantities on the outer circumferential surface of the screw shaft so that the scale part does not participate in power transmission and is not rubbed. To enable accurate reading at all times without being affected by bending or thermal deformation, and to perform highly accurate control.

Configuration In short, the present invention (claim 1) provides a screw shaft having a circular cross section with a lead groove formed therein, and a screw shaft that fits into the lead groove and moves on the screw shaft in synchronization with the rotation of the screw shaft. A feed screw device comprising a nut that moves in the axial direction of the shaft, the screw shaft having a scale as a digital quantity along the lead groove on the outer peripheral surface of the screw shaft, and a reading means for reading the scale. The nut is characterized in that the nut is provided with the following.

The present invention (claim 2) also provides a screw shaft in which a lead groove is formed on a shaft having a circular cross section, and a screw shaft that fits into the lead groove and moves on the screw shaft in synchronization with the rotation of the screw shaft. A feed screw device comprising a nut that moves in the axial direction; The nut is characterized in that the nut is provided with a reading means for reading the scale, audio information, or image information.

Further, the method of the present invention (claim 5) includes recording a scale using a scale recording device on the outer circumferential surface of the screw shaft in which the lead groove is formed, and then simultaneously rotating the screw shaft by an angle corresponding to one scale. In synchronization with the rotation, the screw shaft is moved relative to the scale recording device in the axial direction of the screw shaft by a distance determined by the pitch of the lead groove, and the scale recording device again moves the screw shaft on the outer peripheral surface of the screw shaft. The invention is characterized in that the scale is recorded along the lead groove on the outer circumferential surface of the screw shaft by repeating the operation of recording the scale.

Further, the method of the present invention (claim 6) includes recording the scale on the outer peripheral surface of the screw shaft over the entire length while moving the scale recording device in the axial direction of the screw shaft while the screw shaft is held stationary. , while rotating the screw shaft by an angle corresponding to one graduation, and again moving the scale recording device in the axial direction of the screw shaft, the screw shaft records the scale over the entire length of the screw shaft once. The invention is characterized in that a scale is recorded on the outer circumferential surface of the screw shaft by repeating the steps until the number of steps is reached.

The present invention will be explained below based on embodiments shown in the drawings. 1 to 4, a feed screw device 1 according to the present invention includes a screw shaft 2, a nut 3, and a reading means 4. As shown in FIGS.

1 to 4, the screw shaft 2 is a shaft having a circular cross section, and has lead grooves 2a formed at a constant pitch over substantially its entire length. Lead groove 2a
The cross-sectional shape of the nut 3 varies depending on the type of nut 3 guided by the lead groove 2a, and for example, in combination with the nut 3 of the type in which the steel ball 5 rolls in the lead groove 2a as shown in FIGS. 1 and 3. has a semicircular shape, and in combination with the internally threaded nut 3 shown in FIGS. 2 and 4, it has a trapezoidal shape. In addition, a lead groove 2a is formed on the outer peripheral surface 2d of the screw shaft 2.
A scale 6 as a digital quantity is recorded at predetermined intervals along the line. The scale 6 may be, for example, recorded on a magnetic material as a magnetic change, or may be recorded, for example, by arranging a large number of pits for optical reading.

The nut 3 is fitted into the lead groove 2a and guided, and in synchronization with the rotation of the screw shaft 2, the nut 3 is rotated in the axial direction indicated by the arrow A.
In the nut 3 of the type shown in FIG. A plurality of steel balls 5 fit together and can roll between the lead groove 2a and the semicircular groove 3b as the screw shaft 2 rotates.
Further, in the nut 3 of the type shown in FIG. 2, the inner diameter portion 3a of the nut 3 has a lead groove 2a with a trapezoidal cross section.
A female thread 3c having the same lead as the lead is formed and is fitted into the lead groove 2a without any gap.

The reading means 4 is an optical pickup or the like that optically reads the presence or absence of a magnetic flux-responsive reproduction head or pit such as a magnetoresistive element using a laser or the like, and the detection surface 4a of the reading means 4 faces the scale 6. and is fixed to nut 3. As the screw shaft 2 rotates, arrows A or B move in the axial direction of the screw shaft 2.
While moving in the direction together with the nut 3, the scale 6 is read one after another and a signal is sent out. The signal sent from the reading means 4 is sent to the input/output port 8 as an interface, the CPU 9,
Arithmetic processing is performed by a recording device 10 comprising a RAM 10a and a ROM 10b, and the processed results are transmitted to the motor 11 via the input/output port 8 to control the rotation of the motor 11. The rotation of the motor 11 is configured to control the rotation of the screw shaft 2 via a power transmission device 12 such as a speed reducer.

And the method according to the present invention (claim 5)
6 and 6, a scale 6 is recorded on the outer circumferential surface 2d of the screw shaft 2 on which the lead groove 2a is formed using a scale recording device (not shown), and then the screw shaft 2 is recorded corresponding to one scale. While rotating the screw shaft 2 by an angle in the direction of arrow C, in synchronization with the rotation, the screw shaft 2 is moved relative to the scale recording device in the axial direction (direction of arrow D) by a dimension determined by the pitch P of the lead groove 2a, and then again. The outer peripheral surface 2 of the screw shaft 2 is measured by the scale recording device.
In this method, the scale 6 is recorded along the lead groove 2a of the screw shaft 2 by repeating the operation of recording the scale 6 on the screw shaft 2.

Further, the method of the present invention (claim 6) is shown in FIGS. 7 and 8.
Referring to the figure, while holding the screw shaft 2 in a stationary state, the scale recording device (not shown) is moved in the axial direction of the screw shaft 2 (in the direction of arrow D), and the outer periphery is measured over the entire length of the screw shaft 2. After recording the scale 6 on the surface 2d, rotate the screw shaft 2 by an angle corresponding to one scale in the direction of the arrow E, and again move the scale recording device in the axial direction of the screw shaft 2 while covering the entire length of the screw shaft 2. In this method, the scale 6 is recorded on the screw shaft 2 by repeating the operation of recording the scale 6 on the screw shaft 2 until the screw shaft 2 rotates once.

As another method for recording the scale 6, referring to FIG. 9 and FIG. Alternatively, referring to FIGS. 11 and 12, a shallow groove 2e having a substantially concentric pitch with the lead groove 2a is provided on the outer circumferential surface 2d of the screw shaft 2, and A tape-shaped recording body 14 on which the scale 6 is recorded in advance may be fixed by adhesive or other means.

Effects The present invention is configured as described above, and its effects will be explained below. 1 to 4, when the rotating shaft 15 of the motor 11 rotates according to a command from the CPU 9, the rotational motion is decelerated (or accelerated in some cases) by the power transmission device 12.
and is transmitted to the screw shaft 2. As the screw shaft 2 rotates, the nut 3 fitted into the lead groove 2a of the screw shaft 2 is calculated by the formula P×θ/360 using the pitch P of the lead groove 2a and the rotation angle θ of the screw shaft 2. arrow A or B according to the direction of rotation of the screw shaft 2.
move in the direction. To explain in more detail how the nut 3 moves, in the ball screw type feed screw device 1 shown in FIGS. 1 and 3, when the screw shaft 2 rotates, the lead groove 2a of the screw shaft 2 and the nut 3 The steel ball 5 fitted between the semicircular grooves 3b of the nut 3 moves along the lead groove 2a and the semicircular groove 3b while rolling, and when it reaches the end of the semicircular groove 3b of the nut 3, the steel ball guide The nut 3 is moved in the direction of arrow A or B by passing through the tube 16, returning to the original position, and rolling again between the screw shaft 2 and the nut 3.

In addition, in the feed screw device shown in FIGS. 2 and 4, the lead groove 2a of the screw shaft 2 and the female thread 3c of the nut 3 fit together in the same way as the relationship between a normal screw and a nut, so that the screw The nut 3 is moved as the shaft 2 rotates. The action of both is the same, but the ball screw type feed screw device 1 has a better effect than the screw shaft 2.
The force required to rotate the screw shaft 2 is small, and the screw shaft 2
Since the gap between the nut 3 and the nut 3 can be made small, it is used when more precise feed control is required.

Since the reading means 4 fixed to the nut 3 moves in the direction of arrow A or B together with the nut 3 through the lead groove 2a, the detection surface 4a always faces the scale 6 and is arranged on the outer peripheral surface 2d of the screw shaft 2. scale 6
are read one after another and send out a signal. The signal is
The CPU 9 controls the movement of the motor 11 based on the results of arithmetic processing according to a predetermined procedure.
control the position of

Since the graduations 6 are recorded with magnetism or pits, it is possible to record graduations with a much higher density than the conventional graduations 6, and it is possible to perform position control with higher precision. Further, by differentiating the signal read by the reading means 4 once at time t by the CPU 9, the moving speed of the nut 3 is further calculated by 2 at time t.
The acceleration of the nut 3 can be determined with high precision by differentiating the times, and if the mass of the nut 3, which is an example of a moving object, is measured in advance, the product of the acceleration and the mass can be used to determine the acceleration of the moving object 18. The inertial force acting on the motor is also determined, and the calculation results can be used to perform complex control.

In addition, by recording a special scale 6 at the start point or end point of the scale 6 to identify the start point or end point, the start or end point position of the nut 3 can be easily known.
Further, since the amount of movement from the starting point can be determined by reading the scale 6, the position of the nut 3 can be known at all positions. Furthermore, in cases where the same pattern of operation is repeated, such as position control in a special-purpose machine, audio or image information can be recorded at a predetermined position on the scale 6 to instruct the worker on the next task. , precautions, etc. can be output in the form of audio or images to improve work efficiency and ensure safety.

In the above embodiment, the outer circumferential surface 2d of the screw shaft 2 was explained as the outer diameter portion of the lead groove 2a, but the outer circumferential surface 2d is not limited to the outer diameter portion, but may be the root diameter portion of the lead groove 2a. It's okay to be hot.

Effects The present invention provides a screw shaft in which a lead groove is formed on a shaft having a circular cross section as described above, and a nut that fits into the lead groove and moves in the axial direction of the screw shaft in synchronization with the rotation of the screw shaft. In a feed screw device consisting of This has the effect of eliminating the need for a sensor for detecting the position of the nut and a special sensor for detecting the start or end point of the movement of the nut. Furthermore, this has the effect of increasing the degree of freedom in design, making it possible to achieve an optimal design, and making it possible to downsize the device. Furthermore, there is an effect that position detection accuracy can be improved and precise position control can be performed.

Further, the present invention has the effect of improving work efficiency by properly providing necessary information to the worker through audio or image information, and making it possible to easily perform error-free and safe work. In addition, by providing the information at a high density, the speed, acceleration, or inertial force acting on the moving body can be known with high accuracy, and there is an effect that more accurate control can be performed.

In addition, since we recorded a scale as a digital value on the outer circumferential surface of the screw shaft along the lead groove, we were able to secure a recordable length of 3.14 times the diameter of the screw shaft even with a single thread; This has the effect of being able to secure a very long recording space that is several times the length of the screw thread, and as a result, it has the effect of being able to provide an extremely large amount of scale information to the screw shaft.

In addition, a digital scale is recorded on the outer circumferential surface of the screw shaft, and this can be directly detected and read by the nut's reading means, so it is not just a matter of converting an analog quantity into a digital quantity. First, there is an effect that there is no room for reading errors to enter, and extremely accurate reading accuracy can be obtained.

Furthermore, since the scale is recorded as a digital value on the outer circumferential surface of the screw shaft, the scale part does not participate in power transmission, so it will not be rubbed, and it will not be affected by deflection or thermal deformation of the screw shaft. This has the effect of making it possible to always perform accurate readings and to perform control with very high precision.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway front view of a feed screw device using a pole screw, Figure 2 is a partially cutaway front view of a feed screw device using a trapezoidal screw, and Figure 3 is a schematic diagram of a feed screw device using a ball screw. FIG. 4 is a perspective view of the main part of a feed screw device using a trapezoidal screw, FIGS. 5 and 6 are partial front views of the feed screw showing the scale recording method, and FIGS. 7 and 8 are partial front views of the feed screw. A partial front view of the feed screw showing another scale recording method, FIGS. 9 and 10 are partial perspective views of the feed screw showing still another scale recording method, and FIGS. 11 and 12 are still other scale recording methods. FIG. 3 is a partial perspective view of a lead screw illustrating the method; 1 is a feed screw device, 2 is a screw shaft, 2a is a lead groove, 2d is an outer peripheral surface, 3 is a nut, 4 is a reading means, and 6 is a scale.

Claims (1)

[Scope of Claims] 1. A screw shaft having a circular cross section with a lead groove formed therein, and a screw shaft that fits into the lead groove and moves on the screw shaft in the axial direction of the screw shaft in synchronization with the rotation of the screw shaft. A feed screw device comprising a screw shaft having a scale as a digital quantity along the lead groove on the outer circumferential surface of the screw shaft, and a reading means for reading the scale on the nut. A feed screw device characterized by: 2 Consists of a screw shaft with a circular cross-section and a lead groove formed therein, and a nut that fits into the lead groove and moves on the screw shaft in the axial direction of the screw shaft in synchronization with the rotation of the screw shaft. In the feed screw device, a screw shaft in which information as a digital quantity of at least one of a scale, audio information, and image information is recorded on an outer circumferential surface along a lead groove of the screw shaft, and the scale;
A feed screw device characterized in that the nut is provided with a reading means for reading audio information or image information. 3. The scale, audio information, and image information are magnetic information as digital quantities recorded as magnetic changes in a magnetic material, and the reading means is a magnetic reproducing head responsive to magnetic flux. The feed screw device according to scope 1 or 2. 4. A patent characterized in that the scale, audio information, and image information are information as digital quantities engraved and recorded as pits, and the reading means is an optical pickup that optically reads the pits. A feed screw device according to claim 1 or 2. 5 After recording a scale with a scale recording device on the outer circumferential surface of the screw shaft on which the lead groove is formed, the screw shaft is
The screw shaft is rotated by an angle corresponding to the scale, and at the same time, in synchronization with the rotation, the screw shaft is moved relative to the scale recording device in the axial direction of the screw shaft by a distance determined by the pitch of the lead groove. A scale on a screw shaft of a feed screw device, characterized in that the scale is recorded on the outer peripheral surface of the screw shaft along the lead groove by repeating the operation of recording the scale on the outer peripheral surface of the screw shaft using a scale recording device. Recording method. 6. After recording the scale on the outer peripheral surface of the screw shaft over the entire length while moving the scale recording device in the axial direction of the screw shaft while holding the screw shaft still,
Rotating the screw shaft by an angle corresponding to one graduation, and again moving the scale recording device in the axial direction of the screw shaft, recording the scale over the entire length of the screw shaft while the screw shaft rotates once. A method for recording scales on a screw shaft of a feed screw device, characterized in that a scale is recorded on the outer circumferential surface of the screw shaft by repeating up to . 7. A method for recording a scale on a screw shaft of a feed screw device according to claim 5 or 6, wherein the scale is a scale recorded as a magnetic change on a magnetic material. 8. Claim 5, wherein the scale is a pit carved on the outer peripheral surface of the screw shaft.
A method for recording scales on a screw shaft of a feed screw device according to item 1 or 6.