JP2010216655A - Bearing assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing assembly capable of obtaining a load acting on a rotary member and suitable for a machine tool. <P>SOLUTION: A spacer 2b with an annular encoder function in which a V-groove 3 has two oblique parts (circumferential boundary characteristics in different in two rows) 3a, 3b is provided in a rotary member 6 between two bearings 1b, 1c to detect a change in phase difference of a pulse signal of two oblique parts 3a, 3b of the spacer 2b with the annular encoder function detected by a rotary sensor 4, so that the load acting on the rotary member 6 can be calculated from the phase difference of the pulse signal, and the annular encoder is provided in the spacer 2b between the bearings 1b, 1c so as to be suitable for the machine tool. Furthermore, the rotary sensor 4 is fixed to a bar-like part 5b end of a sensor casing 5, and the sensor casing 5 is fixed to a stationary member 7, so that the rotary sensor 4 can be easily installed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing assembly using a plurality of bearings.

  For example, in a machine tool that performs cutting such as a lathe, milling machine, machining center, etc., if the load during cutting can be detected, the optimum machining conditions that can improve the tool life can be grasped and energy saving can be achieved. Can contribute. For example, if it becomes possible to find a machining condition in which the amount of chips discharged is the same and the cutting load is small, the machining condition is an efficient machining condition, which leads to energy saving and extension of the tool life.

  For example, in Patent Document 1 below, the cutting load is detected using a crystal piezoelectric sensor or a commercially available load sensor. However, a commercially available sensor, such as a quartz piezoelectric vertebra sensor, is expensive, and for example, only one load sensor may be used if only axial direction load detection is performed. However, when performing load detection in the radial direction, a plurality of load sensors are used. It becomes necessary and the cost is further increased.

  Therefore, the present applicant has proposed a bearing assembly with a load detection function described in Patent Document 2 below. In this bearing assembly, two rows of encoders having different circumferential boundary characteristics are installed on the rotating member, and each of the two rows of different circumferential boundary characteristics of the encoder is detected by a rotation sensor and detected by these rotation sensors. The load acting on the rotating member is calculated from the phase difference between the circumferential boundary characteristics. According to this bearing assembly, the load acting on the rotating member can be obtained without using an expensive load sensor.

JP 2002-187048 A JP 2006-317420 A

However, the bearing assembly described in Patent Document 2 is only for use in a wheel hub of an automobile, and some device is required for application to a machine tool.
The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide a bearing assembly suitable for a machine tool that can determine a load acting on a rotating member. is there.

  In order to solve the above problems, a bearing assembly according to the present invention is a bearing assembly using a plurality of bearings, and two rows of annular encoders having different circumferential boundary characteristics are installed on the rotating member between the plurality of bearings. And at least two rotation sensors for detecting different circumferential boundary characteristics of the two annular encoders on the stationary member, and two circumferential boundaries of the annular encoders detected by the rotation sensor. A change in the phase difference of the characteristic pulse signal is detected, the rotation sensor is fixed to the tip of the rod-shaped portion of the sensor casing, and the sensor casing is fixed to a stationary member.

  Further, in a bearing assembly using a plurality of bearings, a plurality of annular encoders having different circumferential boundary characteristics in two rows are installed on the rotating member between the plurality of bearings and at positions spaced apart from each other by a predetermined distance. At least four rotation sensors for detecting different circumferential boundary characteristics of the two rows of the respective annular encoders are installed on at least four stationary members, and the two circumferential boundaries of the annular encoders detected by the respective rotation sensors are different. A change in phase difference of a characteristic pulse signal is detected, each rotation sensor is fixed to the tip of a rod-like portion of an individual sensor casing, and the sensor casing is fixed to a stationary member. .

Further, a load acting on the rotating member is calculated by calculation from a change in the phase difference of the detected pulse signal.
Further, the temperature of the rotating member is calculated by calculation from the change in the phase difference of the pulse signal detected by each of the rotation sensors.
Further, among the two different circumferential boundary characteristics of the annular encoder, at least one of the boundary characteristics gradually shifts in the axial direction with the rotation of the annular encoder. It is.

Further, the two rotation sensors are arranged at different positions in the axial direction of the rotating member and at the same position in the circumferential direction or at positions shifted in the circumferential direction.
In addition, a plurality of the rotation sensors are arranged in the circumferential direction of the rotating member.
Further, the sensor housing is fixed to the stationary member while being shifted from the central axis of the annular encoder in the cross section orthogonal to the axis of the rotating member.

Further, the rod-shaped portion of the sensor casing is formed in a bifurcated shape, and a rotation sensor is fixed to each of the bifurcated rod-shaped portion.
Further, the tip of the rod-like portion of the sensor casing and the surface on which the rotation sensor is fixed is an ellipse, an ellipse, or a rectangle.
Further, the sensor housing is fixed to the stationary member by a separate support tool and fixing tool.

Further, a positioning member is interposed between the sensor casing and the stationary member.
Further, when a plurality of bearings are arranged side by side to support the rotating member, a rotation sensor is disposed at the center of the plurality of bearings.
Further, a signal cable from the rotation sensor is inserted into a conduit formed in advance in the stationary member.
Further, two or more annular encoders having different numbers of generated pulses per unit rotation are installed on a common rotating member.

  Thus, according to the bearing assembly of the present invention, two annular encoders having different circumferential boundary characteristics are installed on the rotating member between the plurality of bearings, and the annular encoder detected by the rotation sensor is used. Since the change in the phase difference of the pulse signals having two different circumferential boundary characteristics is detected, the load acting on the rotating member can be calculated from the phase difference of the pulse signals, and the annular encoder is connected between the bearings. By providing it in the spacer, it can be used suitably for machine tools, and the rotation sensor is fixed to the tip of the rod-shaped part of the sensor housing, and the sensor housing is fixed to the stationary member. Becomes easier.

Moreover, since the load acting on the rotating member is calculated by calculation from the change in the phase difference of the detected pulse signal, the load acting on the rotating member of the machine tool can be obtained appropriately.
By installing two sets of an annular encoder and a rotation sensor at a predetermined distance on the rotating member, it becomes possible to detect a change in length due to thermal expansion and contraction of the rotating member. The temperature can be detected.

In addition, at least one of the two different circumferential boundary characteristics of the annular encoder is such that the boundary characteristics gradually shift in the axial direction as the annular encoder rotates. The boundary characteristics can be easily obtained.
In addition, since two rotation sensors are arranged at different positions in the axial direction of the rotation member and at the same position in the circumferential direction or at positions shifted in the circumferential direction, the position of the pulse signal from these rotation sensors is determined. A load acting in the axial direction of the rotating member can be obtained by a change in phase difference.

Further, since a plurality of rotation sensors are arranged in the circumferential direction of the rotation member, a load acting in the radial direction of the rotation member can be obtained by a change in the phase difference of the pulse signals from these rotation sensors.
Also, since the sensor housing is fixed to the stationary member by shifting from the central axis of the annular encoder in the cross section orthogonal to the axis of the rotating member, the tip end area of the rod-shaped portion of the sensor housing facing the annular encoder is increased. The rotation sensor can be easily installed and fixed.

In addition, since the rod-shaped portion of the sensor housing is formed in a bifurcated shape and the rotation sensor is fixed to each of the bifurcated rod-shaped portions, the total area of the tip of the rod-shaped portion of the sensor housing facing the annular encoder is increased. This makes it easy to dispose and fix the rotation sensor.
In addition, the surface of the rod-shaped portion of the sensor housing and the surface on which the rotation sensor is fixed is an ellipse, an ellipse, or a rectangle. This makes it easy to dispose and fix the rotation sensor.

In addition, since the sensor casing is fixed to the stationary member with separate supports and fixtures, the method of fixing the lubrication nozzle can be diverted, and the sensor casing can be easily fixed to the stationary member. It becomes possible.
Further, since the positioning member is interposed between the sensor casing and the stationary member, the positioning of the sensor casing is facilitated.
Further, when a plurality of bearings are arranged side by side to support the rotating member, the rotation sensor is disposed in the center of the plurality of bearings, so that an error in the change in phase difference of the pulse signal due to temperature expansion can be avoided.

In addition, since the signal cable from the rotation sensor is inserted into a conduit formed in advance in the stationary member, there is no need to open a new cable insertion hole.
In addition, by installing two or more annular encoders with different number of generated pulses per unit rotation on a common rotating member, it is possible to use different annular encoders according to the rotating speed of the rotating member. Thus, a change in the phase difference of the pulse signal can be detected.

It is a longitudinal cross-sectional view of the machine tool which shows 1st Embodiment of the bearing assembly of this invention. It is a perspective view of the spacer with an annular encoder function used for the machine tool of FIG. It is a perspective view of the rotation sensor used for the machine tool of FIG. It is explanatory drawing of the fixing method of the sensor housing | casing of FIG. It is explanatory drawing of the positioning method of the sensor housing | casing of FIG. It is a perspective view which shows the various forms of a sensor housing | casing. It is arrangement | positioning explanatory drawing of the circumferential direction of the rotation sensor used for the machine tool of FIG. It is a schematic block diagram of the machine tool of FIG. It is a schematic block diagram of other embodiment of the machine tool of FIG. It is explanatory drawing of the sensor housing | casing which shows 2nd Embodiment of the bearing assembly of this invention. It is explanatory drawing of the sensor housing | casing which shows 3rd Embodiment of the bearing assembly of this invention. It is a schematic block diagram of the machine tool which shows 4th Embodiment of the bearing assembly of this invention. It is a schematic block diagram of the machine tool which shows 5th Embodiment of the bearing assembly of this invention. It is a characteristic diagram which shows the relationship between a temperature dependence phase difference and temperature. It is a flowchart which shows an example of the temperature calculation process procedure performed with a control apparatus. It is a schematic block diagram of the machine tool which shows other embodiment of the bearing assembly of this invention.

Next, an embodiment of the bearing assembly of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a bearing assembly of the present invention. The bearing assembly includes four bearings 1a to 1d for supporting a rotating member 6 such as a main shaft of a machine tool, for example. Spacers 2a to 2c are interposed between the four bearings 1a to 1d, respectively. As is well known, the spacer regulates the dimension between the bearings, and also serves to ensure the preload when a preload is applied to the bearing, for example. The spacer is disposed not only on the inner ring side of the bearings 1a to 1d but also on the outer ring side. In this embodiment, the function of the annular encoder described later is added on the rotating wheel side, that is, the inner ring side. Only the inner ring side, that is, only the spacers 2a to 2c on the rotating member 6 side will be described.

  In this embodiment, the function of the annular encoder is added to the spacer 2b between the center two bearings 1b and 1c. The spacer 2b with an annular encoder function is a steel cylindrical ring provided with a predetermined width (length in the axial direction) in order to regulate the distance between the bearings 1b and 1c, for example, as shown in FIG. On the outer periphery, a symmetric V-groove 3 having a tapering tip at the center in the width direction is formed in the same direction when viewed from the radial direction at every predetermined circumferential length or every predetermined phase. The V-groove 3 is for detecting, as a pulse signal, a change in magnetic flux density of the oblique portions 3a and 3b at both ends of the rotating V-groove spacer width direction, for example, by a rotation sensor described later. That is, since the steel spacer 2b is a magnetic body, when a magnetic force is applied from the rotation sensor and a current generated on the rotation sensor side is detected, a sinusoidal wave is formed when the V-groove 3 as a recess approaches and then separates. Current change occurs. If this current value is turned on / off at a predetermined threshold, a pulse signal can be obtained. It should be noted that substantially the same operation can be obtained even if a convex portion is used instead of the groove.

  Returning to FIG. 1, a plurality of rotation sensors 4 are arranged on the outer periphery of the spacer 2 b with an annular encoder function. In this embodiment, two rotation sensors 4 are arranged side by side in the axial direction of the rotation member 6 with respect to one sensor housing 5 (in fact, slightly shifted as will be described later). That is, of the two rotation sensors 4 provided in one sensor housing 5, one rotation sensor 4 faces one oblique portion 3a of the V groove 3 of the spacer 2b with annular encoder function. The other rotation sensor 4 faces the other oblique portion 3b of the V groove 3.

  FIG. 3 a shows an example of the rotation sensor 4 and the sensor housing 5. As described above, the rotation sensor 4 applies a magnetic force to the steel spacer 2b with an annular encoder function, and the magnetic flux density generated in the V groove 3 portion when the spacer 2b with the annular encoder function rotates. Is detected as a change in current value, and is turned on / off at a predetermined threshold value to output a pulse signal. For this reason, the rotation sensor 4 is composed of a magnetoelectric conversion element such as a Hall element facing the V groove 3 and a permanent magnet disposed on the back side of the magnetoelectric conversion element, that is, on the side opposite to the V groove 3. Yes. Of course, a function other than the sensor may be provided with a function of converting to a pulse signal. In addition to the passive type rotation sensor described above, the rotation sensor 4 has a configuration in which a permanent magnet magnetized in a V shape is disposed so as to face a Hall element as described in, for example, JP-A-2006-317420. It is also possible to use an active type rotation sensor having In the present invention, various forms of rotation sensors can be applied.

  The sensor housing 5 includes a small-diameter rod-like portion 5b that holds the rotation sensor 4 on the front end surface, and a large-diameter base portion 5a that is connected to the rear end portion of the rod-like portion 5b. The large-diameter base portion 5a includes a sensor housing. A recess 5 c for fixing the body 5 to the stationary member 7 is provided. FIG. 4 shows details of the method for fixing the sensor housing 5. In the present embodiment, the support 8 is accommodated in the recess 5c of the sensor housing 5, and the support 8 is fixed to the stationary member 7 with a fixing tool 9 such as a bolt. This fixing method is the same as the method for fixing a lubrication nozzle used in a machine tool, for example, and is highly versatile. The method of fixing the sensor housing 5 to the stationary member 7 is not limited to the above. For example, a flange is provided at the large-diameter base of the sensor housing, and a bolt is inserted into a bolt hole provided in the flange. The bolt may be screwed and fixed to the stationary member.

  Further, as shown in FIG. 5, for example, a through hole is formed in the large-diameter base portion 5a of the sensor housing 5, a positioning pin 11 is inserted into the through hole, and the positioning pin 11 is inserted into the stationary member 7 to thereby form the sensor housing. 5 positioning may be performed. In this way, not only the positioning of the sensor housing 5 is facilitated, but also the rotation of the columnar large-diameter base portion 5a that is easy to rotate is prevented, whereby the position of the rotation sensor 4 is accurately determined. Can do. As the positioning member of the sensor housing 5, a known positioning member such as a key can be used in addition to the positioning pin.

  Two rotation sensors 4 are disposed obliquely on the front end surface of the rod-like portion 5 b of the sensor housing 5. Since the sensor housing 5 is fixed to the stationary member 7 so that the left-right direction in FIG. 3 is parallel to the axial direction of the rotating member 6, the two rotation sensors 4 are slightly different from the axial direction of the rotating member 6. It's off. Further, the two rotation sensors 4 are slightly shifted in the circumferential direction of the spacer 2b with an annular encoder function. The reason will be described later. In addition, when using for a machine tool, there exists a possibility that the rotation sensor 4 may get wet with lubricating oil, and when it gets wet with lubricating oil, there exists a possibility that the rotation sensor 4 may break down. Therefore, as shown in FIG. 3b, the tip of the rod-like portion 5b of the sensor housing 5 may be covered with the rotation sensor 4 with a mold 10 such as a resin. It can prevent getting wet with the lubricating oil.

  FIG. 6 shows various forms of the sensor housing 5. Among these, in FIG. 6a, the front end surface of the rod-shaped portion 5b of the sensor housing 5, that is, the fixed surface of the rotation sensor 4 is an ellipse, an ellipse in FIG. 6b, and a rectangle in FIG. 6c. Each of these sensor housings 5 is fixed to the stationary member 7 so that the short axis direction or the short side direction of the fixed surface is the axial direction of the rotating member 6. When the rotating member is supported by a plurality of bearings, the distance between the bearings is set short. Although it is necessary to install the rotation sensor 4 so as to face the spacer disposed between the short bearings, naturally, the length of the rod-shaped portion 5b of the sensor housing 5 for fixing the rotation sensor 4 in the axial direction of the rotating member is also included. It is prescribed. Therefore, the tip surface of the rod-shaped portion 5b of the sensor housing 5 is an ellipse, an ellipse, or a rectangle, and the sensor housing 5 is attached to the stationary member 7 so that the short axis direction or the short side direction is the axial direction of the rotating member 6. By fixing, the width of the rod-shaped portion 5b (length in the axial direction of the rotating member) can be shortened while securing the mounting area of the rotation sensor 4.

  In the present embodiment, as shown in FIG. 7, a total of three sensor housings 5 are arranged around the rotating member 6 every 120 °. That is, a pair of two rotation sensors 4 is arranged in the axial direction of the rotating member 6 around the one spacer 2b with an annular encoder function, and the pair is a spacer with the annular encoder function. It will be arrange | positioned by 3 pairs equidistantly around 2b.

  A method for obtaining the load acting on the rotating member 6 from the outputs of the rotation sensors 4 will be briefly described. For example, when a load in the axial direction (axial direction) acts on the rotating member 6, when there is no load in the axial direction, the pulse signals of the two rotation sensors 4 arranged in the axial direction of the rotating member 6 are used. There is no misalignment, that is, the two rotation sensors 4 are axially applied to the rotating member 6 from the state in which the two oblique portions 3a and 3b of the V groove 3 of the spacer 2b with the annular encoder function are detected without phase misalignment. When a load in the direction is applied, the position of the spacer 2b with the annular encoder function is shifted to one of the axial directions of the rotating member 6, that is, displaced. When the position of the spacer 2b with the annular encoder function is shifted in the axial direction of the rotating member 6 in this way, 2 of the V groove 3 of the spacer 2b with the annular encoder function detected by the two rotation sensors 4 is detected. A phase shift occurs in the two oblique portions 3a and 3b. Thus, when a phase shift occurs in the two oblique portions 3a and 3b of the V groove 3 of the spacer 2b with the annular encoder function detected by each of the two rotation sensors 4, the two rotation sensors 4 output the signals. A change in phase difference occurs in the pulse signal. This change in phase difference is equivalent to the amount of displacement of the spacer 2b with the annular encoder function due to the load in the axial direction of the rotating member 6, so that the control device described later determines the axial direction of the rotating member 6 from the phase difference of the pulse signal. The load on can be calculated.

  Further, for example, when a radial (radial) load is applied to the rotating member 6, when there is no radial load, three pairs (of the pairs) arranged in the circumferential direction of the rotating member 6 are provided. There is no deviation in the pulse signal of the rotation sensor 4 of the rotation sensor 4). That is, each of the three pairs (or three) of rotation sensors 4 has the annular encoder function spacer 2b. When a radial load is applied to the rotary member 6 from a state where the two (or any one) oblique portions 3a, 3b of the V-groove 3 are detected without phase shift, the spacer 2b with the annular encoder function is applied. The position is shifted, that is, displaced in any one of the radial directions of the rotating member 6. Thus, when the position of the spacer 2b with the annular encoder function is shifted in the radial direction of the rotating member 6, the spacer 2b with the annular encoder function detected by each of the three pairs (or three) of the rotation sensors 4 is detected. A phase shift occurs in the two (or any one) oblique portions 3a and 3b of the V-groove 3. In this way, the phase is applied to two (or any one) of the oblique portions 3a and 3b of the V groove 3 of the spacer 2b with the annular encoder function detected by each of the three pairs (or three) of rotation sensors 4. When the deviation occurs, a change in phase difference occurs in the pulse signals output from the three pairs of rotation sensors 4. This change in the phase difference is equivalent to the amount of displacement of the spacer 2b with the annular encoder function due to the load in the radial direction of the rotating member 6, so that the control device described later determines the radial direction of the rotating member 6 from the phase difference of the pulse signal. The load on can be calculated.

  Therefore, in the present embodiment, the two oblique portions 3a and 3b of the V-groove 3 are defined as two different circumferential boundary characteristics. The circumferential boundary characteristic indicates, for example, an edge of a detected pulse signal. In the two oblique portions 3 a and 3 b of the V groove 3, the edge of the detected pulse signal gradually shifts in the axial direction of the rotating member 6 with the rotation of the spacer 2 b with the annular encoder function. When a load in the axial direction or radial direction is applied to the rotating member 6 in a state where the pulse signals of the two oblique portions 3a and 3b of the V-groove 3 are detected, two rows on the detected time axis The detection pulse has a time difference, that is, a phase difference between the two detection pulses. Since it is for detecting a change in the phase difference between the two detection pulses, the two oblique portions 3a and 3b of the V-groove 3 have two different circumferential boundary characteristics. In addition, even if it is a V-shaped convex part instead of a V-groove, since it has the same function, it can be said also in this case that two rows have different circumferential boundary characteristics. In addition, in this case, since the V-shaped magnetic pole is rotated and the sinusoidal current generated by the proximity and separation of the oblique portion is turned on and off at a predetermined threshold, as described later, the same function is obtained. Are also two different circumferential boundary characteristics. Further, it is preferable to use a phase difference ratio obtained by dividing the phase difference by the pulse period as the phase difference of the detection pulse. That is, as described above, when the time difference between detection pulses is a phase difference, even if the rotation speed changes, the pulse period changes, so the time difference between detection pulses also changes. On the other hand, since the phase difference ratio obtained by dividing the phase difference by the pulse period does not change even if the rotation speed changes, this phase difference ratio is preferably used as the phase difference.

  Here, the reason why the two rotation sensors 4 forming the pair are displaced in the circumferential direction of the spacer 2b will be described. The two rotation sensors 4 that form a pair can detect a change in the phase difference of the detection pulse due to, for example, the load applied to the rotating member in the axial direction. In detecting the change in the phase difference of the detection pulse, generally, one of the detection pulses is used as a reference, and the time until the other detection pulse is reached is measured. At this time, if the time from one detection pulse to the other detection pulse is measured on the assumption that the two detection pulses are not out of phase, for example, when there is no phase deviation of the other detection pulse from one detection pulse If the time is “1” when the phase of the other detection pulse is shifted by one wavelength with respect to one detection pulse, the time to be measured is “1” up to “1”. It extends to. Even if the phase does not substantially shift by one wavelength, the values appear in the vicinity of “0” and “1”, so that a memory and a counter need to have a large capacity, and the calculation load increases. On the other hand, if the other detection pulse is detected with a phase shift of 0.5 pulse wavelength, for example, with respect to one detection pulse as an initial setting, the value is only in the vicinity of “0.5”. As a result, the capacity of the memory and the counter and the calculation load can be reduced. In order to realize this, for example, when the different circumferential boundary characteristics of the two rows are two oblique portions of the V-groove, the pair of two rotation sensors 4 are placed in the circumferential direction of the spacer 2b as “0. 5 ”is shifted by the pulse wavelength, the initial value of the phase shift is set to“ 0.5 ”, and the change in the phase difference from the initial value is detected as the change in the phase difference between the two detection pulses. As described above, it is preferable to use the phase difference ratio obtained by dividing the actual phase difference by the pulse period as the phase difference of the detection pulse.

  FIG. 8 is an overall configuration diagram of a spindle unit of a machine tool to which the bearing assembly of the present embodiment is applied. For example, various high-speed rotation types such as a high-speed rotation type general-purpose machine tool such as a lathe, a milling machine, and a machining center are illustrated. It is also used for dedicated machine tools. The rotating member 6 is a main shaft, and the stationary member 7 is a housing. The main shaft which is the rotating member 6 is inserted into the housing which is the stationary member 7 from the left side of the drawing, and a cap is fixed to the left end opening of the housing so as not to come off.

  The output of the rotation sensor 4 is read by the external control device 20 via the signal cable 19. In the control device 20, for example, the relationship between the phase difference of the pulse signal from the rotation sensor 4 sampled in advance and the load in the radial direction and the load in the axial direction acting on the rotation member 6 is stored. The radial load and the axial load acting on the rotating member 6 are calculated from the phase difference of the pulse signals. In addition, according to the rotation sensor 4 of this embodiment, it is also possible to calculate the load from other directions using the same method, and also in that case, the load from each direction sampled in advance, The phase difference of the pulse signal from the rotation sensor 4 generated at the time may be stored, and the load acting on the rotating member 6 may be calculated by calculation from the detected phase difference of the pulse signal from the rotation sensor 4.

  FIG. 9 shows an overall unit configuration diagram of a spindle device of a machine tool to which a bearing assembly of another embodiment is applied. In this embodiment, for example, the sensor housing 5 is attached to the lower side of the figure, and the signal cable 19 is inserted into the lubrication or cooling conduit 12 previously opened in the stationary member 7. In this way, it is not necessary to newly open a hole for the signal cable 19 in the stationary member 7.

  As described above, in the bearing assembly of the present embodiment, the V-groove 3 includes two oblique portions (two rows of different circumferential boundary characteristics) 3a and 3b. The phase difference between the two oblique portions (two different circumferential boundary characteristics) 3a and 3b of the spacer 2b with an annular encoder function, which is installed on the rotating member 6 between 1c and detected by the rotation sensor 4 The load acting on the rotating member 6 can be calculated from the phase difference of the pulse signal by detecting the change of the pulse signal, and the annular encoder is provided in the spacer 2b between the bearings 1b and 1c. The rotation sensor 4 can be suitably used, and the rotation sensor 4 can be easily installed by fixing the rotation sensor 4 to the tip of the rod-like portion 5b of the sensor housing 5 and fixing the sensor housing 5 to the stationary member 7.

Further, by calculating the load acting on the rotating member 6 by calculation from the change in the phase difference of the detected pulse signal, the load acting on the rotating member 6 of the machine tool can be appropriately obtained.
Of the two different circumferential boundary characteristics of the spacer 2b with the annular encoder function, the boundary characteristic gradually shifts in the axial direction as the spacer 2b with the annular encoder function rotates. Since the inclined portions 3a and 3b are used, different circumferential boundary characteristics can be easily obtained.

Since two rotation sensors 4 are arranged at different positions in the axial direction of the rotation member 6 and at the same position in the circumferential direction or at positions shifted in the circumferential direction, pulses from these rotation sensors 4 are arranged. The load acting in the axial direction (axial direction) of the rotating member 6 can be determined by the change in the signal phase difference.
In addition, since a plurality of rotation sensors 4 are arranged in the circumferential direction of the rotation member 6, the rotation sensor 4 acts in the radial direction (radial direction) due to the change in the phase difference of the pulse signals from the rotation sensors 4. Load to be obtained.

Further, the end of the rod-shaped portion 5b of the sensor housing 5 and the surface on which the rotation sensor 4 is fixed is an ellipse, an ellipse, or a rectangle, so that the rod-shaped portion that fixes the rotation sensor 4 with the same width of the rod-shaped portion 5b. The tip area can be increased, and the rotation sensor 4 can be easily disposed and fixed.
In addition, since the sensor housing 5 is fixed to the stationary member 7 with the separate support 8 and fixture 9, the method of fixing the lubricating nozzle can be diverted, and the sensor housing 5 can be easily fixed to the stationary member 7. 7 can be fixed.

In addition, since the positioning member such as the positioning pin 11 is interposed between the sensor housing 5 and the stationary member 7, the positioning of the sensor housing 5 is facilitated and the rotation of the sensor housing 5 is prevented.
In addition, when the plurality of bearings 1a to 1d are arranged side by side to support the rotating member 6, the rotation sensor 4 is disposed at the center of the plurality of bearings 1a to 1d. Errors can be avoided.
Further, since the signal cable from the rotation sensor is inserted into the duct 12 formed in advance in the stationary member 7, it is not necessary to open a new cable insertion hole.

  Next, a second embodiment of the bearing assembly of the present invention will be described with reference to FIG. The spindle device of the machine tool to which the bearing assembly of this embodiment is applied is the same as that of FIG. 1 of the first embodiment, and detailed description thereof is omitted. In the present embodiment, two rod-like portions 5b are projected from the base portion 5d of the sensor housing 5, and the rotation sensors 4 are fixed one by one to their respective front end surfaces. As shown in FIG. 10c, the rotation sensors 4 are arranged so as to be aligned in the circumferential direction of the spacer 2b with an annular encoder function. The base 5d of the sensor housing 5 is provided with flanges 5f protruding on both outer sides in the arrangement direction of the rod-like portions 5b, and a bolt hole 5g is formed in each of them. When the sensor housing 5 is fixed to the stationary member 7, the base portion 5d is set at a predetermined position, and then the bolt 13 is inserted into the bolt hole 5g and screwed into the screw hole formed in the stationary member 7 and tightened. And fix. In addition, the code | symbol 5e in a figure is a signal cable guide.

As described above, for example, the rotation sensor 4 for detecting the axial load acting on the rotating member 6 may be displaced in the circumferential direction of the spacer 2b with the annular encoder function. There may be no problem even if the spacers 2b with the annular encoder function are juxtaposed in the circumferential direction and the rotation sensor 4 is fixed to the respective front end surfaces. In addition, by providing two rod-like portions 5b projecting in this way, that is, in a bifurcated shape, the total area of their tip surfaces, that is, the fixed area of the rotation sensor 4 can be secured, and the rotation is correspondingly increased. The degree of freedom of the layout of the sensor 4 is increased.
Thus, in the bearing assembly of this embodiment, the rod-shaped portion 5b of the sensor housing 5 is formed in a bifurcated shape, and the rotation sensor 4 is fixed to each of the bifurcated rod-shaped portion 5b, thereby providing an annular encoder function. The total tip area of the rod-like portion 5b of the sensor housing 5 facing the spacer 2b can be increased, and the rotation sensor 4 can be easily disposed and fixed.

  Next, a third embodiment of the bearing assembly of the present invention will be described with reference to FIG. The spindle device of the machine tool to which the bearing assembly of this embodiment is applied is the same as that of FIG. 1 of the first embodiment, and detailed description thereof is omitted. The periphery of the base portion 5d of the sensor housing 5 of this embodiment is similar to that of the second embodiment of FIG. 10, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. The specific method for fixing the sensor housing 5 to the stationary member 7 is also the same as that in the second embodiment shown in FIG. In the present embodiment, there is only one bar 5b protruding from the base 5d of the sensor housing 5. In the present embodiment, as clearly shown in FIG. 11 c, the sensor housing 5, more precisely, the rod-like portion 5 b projecting from the sensor housing 5 in the cross section perpendicular to the axis of the rotating member 6 is formed into an annular encoder. It is fixed to the stationary member 7 in a state shifted from the central axis of the spacer 2b with function. As described above, when the rod-like portion 5b of the sensor housing 5 is shifted from the central axis of the spacer 2b with the annular encoder function, the portion where the rod-like portion 5b is closest to the outer peripheral surface of the spacer 2b with the annular encoder function is , It becomes a diagonal direction slightly shifted from the radial direction.

When the distal end surface of the rod-shaped portion 5b of the sensor housing 5 is formed so as to face the outer peripheral surface of the spacer 2b with the annular encoder function in an oblique direction slightly deviated from the radial direction, the distal end surface becomes the rod-shaped portion 5b. It becomes the surface which cut | disconnected diagonally with respect to the protruding direction. As is clear from FIGS. 11a and 11b, for example, when the rod-like portion 5b is a cylinder, the tip surface oblique to the projecting direction of the rod-like portion 5b is elliptical. The tip surface of the elliptical rod-shaped portion 5b that is oblique to the projecting direction has a larger area than the tip surface of the circular rod-shaped portion 5b that is orthogonal to the projecting direction, as is apparent from FIG. 3, for example. . If the tip area of the rod-like portion 5b of the sensor housing 5 is increased, the fixed area of the rotation sensor 4 can be secured, and the degree of freedom in layout of the rotation sensor 4 is increased accordingly. The position of the rod-like portion 5b of the sensor housing 5 is not limited to the above, and for example, the tip of the rod-like portion 5b in FIG. 11 is directly beside the central axis of the spacer 2b with annular encoder function. It may be. That is, as long as the rod-like portion 5b of the sensor housing 5 is displaced from the central axis of the spacer 2b with the annular encoder function, the tip portion of the rod-like portion 5b may be located anywhere.
Thus, in the bearing assembly of the present embodiment, the sensor housing 5 is displaced from the central axis of the spacer 2b with the annular encoder function and fixed to the stationary member 7 in the cross section orthogonal to the axis of the rotating member 6. The tip area of the rod-like portion 5b of the sensor housing 5 facing the spacer 2b with the annular encoder function can be increased, and the rotation sensor 4 can be easily disposed and fixed.

  Next, 4th Embodiment of the bearing assembly of this invention is described using FIG. The spindle device of the machine tool to which the bearing assembly of the present embodiment is applied is similar to that of FIG. 8 of the first embodiment. Description is omitted. In this embodiment, in addition to the spacer 2b with the annular encoder function of the first embodiment, an annular encoder function is added to the left spacer 2a in the figure. Fig. 12c shows a spacer 2b with an annular encoder function in the center of the figure, and Fig. 12b shows a spacer 2a with an annular encoder function on the left side of the figure. Needless to say, the rotation sensor 4 similar to that of the first embodiment is also disposed facing the spacer 2a with an annular encoder function in a state of being fixed to the sensor housing 5. However, the arrangement pitch of the V-groove 3 is different between the two annular encoder function spacers 2a and 2b. Specifically, the arrangement pitch of the V-grooves 3 in the spacer 2b with the annular encoder function at the center in the drawing is wide, and the arrangement pitch of the V-grooves 3 in the spacer 2a with the annular encoder function at the left in the drawing is narrow. That is, when the two annular encoder function spacers 2a and 2b are rotating at a constant speed, the number of pulse signals detected per unit rotation from the annular encoder function spacer 2b in the center of the figure is small. The number of pulse signals detected per unit rotation from the spacer 2a with the annular encoder function on the left in the figure is large.

  In the present embodiment, the control device 20 switches between the annular encoder function spacers 2a and 2b used for calculating the load acting on the rotating member 6 in accordance with the rotational speed of the rotating member 6. Specifically, in a rotation speed region lower than a predetermined value, a load is calculated based on a change in the phase difference of the pulse signal detected from the spacer 2a with the annular encoder function on the left side of the figure, and a rotation speed higher than the predetermined value is obtained. In the area, the load is calculated based on the change in the phase difference of the pulse signal detected from the spacer 2b with the annular encoder function in the center of the figure.

  As is well known, high-speed rotating machine tools such as lathes, milling machines, and machining centers use a wide range of rotational speeds from low speed to high speed. For example, when the rotating member 6 is rotating at a low speed, the load is calculated based on the change in the phase difference of the pulse signal from the spacer 2b with the annular encoder function with a small number of generated pulse signals per unit rotation. Since the number of detected pulses per unit time is too small, accurate load calculation becomes difficult. On the other hand, when the rotating member 6 is rotating at a high speed, the load is calculated based on the change in the phase difference of the pulse signal from the spacer 2a with the annular encoder function with a large number of generated pulse signals per unit rotation. The number of detected pulses is too large with respect to the sampling period of the arithmetic processing, the capacity of the memory, the counter, etc. is insufficient, or the arithmetic load becomes excessive. Therefore, as described above, in the rotational speed region lower than the predetermined value, the load is calculated based on the change in the phase difference of the pulse signal detected from the spacer 2a with the annular encoder function on the left side of the figure, and is higher than the predetermined value. In the rotation speed region, the load is calculated based on the change in the phase difference of the pulse signal detected from the spacer 2b with the annular encoder function in the center of the figure. Thereby, the load which acts on the rotation member 6 correctly in a wide rotation speed area | region is computable. The number of spacers with annular encoder function is not limited to two, and may be set as appropriate according to the number of rotation speed regions for which a load is to be calculated.

  As described above, in the bearing assembly according to the present embodiment, the two spacers 2a and 2b with an annular encoder function having different numbers of generated pulses per unit rotation are installed on the common rotating member 6. The spacers 2a and 2b with the annular encoder function can be properly used according to the rotation speed, and the change in the phase difference of the pulse signal can be detected in a wide rotation speed region.

  Next, a fifth embodiment of the bearing assembly of the present invention will be described with reference to FIG. The spindle device of the machine tool to which the bearing assembly of the present embodiment is applied is similar to that of FIG. 8 of the first embodiment. Description is omitted. In the present embodiment, in addition to the spacer 2b with the annular encoder function of the first embodiment, the bearings 1a to 1d of the rotating member 6 are separated from the spacer 2b with the annular encoder function by a considerable distance to the right. A spacer 2 d with an annular encoder function is disposed between the inner ring of the bearing 1 e that supports the other end on the opposite side and the step portion 6 a formed on the rotating member 6. Of course, the spacer 2d with the annular encoder function is the same as the first embodiment except that the rotation sensor 40 has the same structure as that of the first embodiment except that the length of the rod-shaped portion 5b is long. The sensor housing 50 having the configuration is disposed so as to be opposed to the sensor housing 50. The output of the rotation sensor 40 is supplied to the control device 20 described above via a signal line 41.

In the present embodiment, the spacer 2b with an annular encoder function is disposed at the center position of the bearings 1a to 1d on the end side where the cutting tool of the rotating member 6 is mounted. A spacer 2d with an annular encoder function is arranged at the position of the bearing 1e that supports the opposite side of the rotating member 6 that is separated by a predetermined distance.
Therefore, the axial displacement of the rotating member 6 due to the axial load applied to the rotating member 6 is equally transmitted to the spacers 2b and 2d with the annular encoder function, and the rotation sensors 4 and 40 have substantially the same phase difference. The detection signal can be obtained.

However, the thermal expansion and contraction due to the temperature change of the rotating member 6 itself changes the distance between the spacers 2b and 2d with the annular encoder function. 40 can be detected as a phase difference.
In this case, the tool mounting portion side of the rotating member 6 is supported by the four bearings 1a to 1d, and the opposite side is supported by the one bearing 1e, and the tool mounting portion side has a high support strength. The effects of thermal expansion and contraction appear in such a manner that the bearing 1e side is displaced starting from the bearings 1a to 1d side. Therefore, the spacer 2d with an annular encoder function generates an axial displacement in which a temperature displacement due to thermal expansion or contraction is added to a load displacement due to an axial load applied to the rotating member 6, and this axial displacement is detected by the rotation sensor 40. Thus, a phase difference corresponding to the axial displacement is detected.

  On the other hand, the relationship between the temperature T and the displacement amount ΔL is obtained in advance based on the length L between the spacers 2b and 2d with the annular encoder function and the linear expansion coefficient α of the rotating member 6, and the displacement amount ΔL and the rotation sensor are further determined. A temperature calculation map representing the relationship between the temperature T and the temperature dependent phase difference Δφb shown in FIG. 14 is created by controlling the relationship between the temperature dependent phase difference Δφb among the phase differences φb detected at 40. The data is stored in a storage device such as a ROM, RAM, or hard disk in the device 20.

  And the control apparatus 20 is comprised by arithmetic processing apparatuses, such as a microcomputer, and performs the temperature calculation process shown in FIG. This temperature calculation process is executed as a timer interrupt process executed every predetermined time (for example, 1 minute) for a predetermined main program, for example. In this temperature calculation process, first, in step S1, the phase differences Δφa and Δφb detected by the rotation sensor 4 and the rotation sensor 40 are read, and then the process proceeds to step S2 where the phase difference φa is subtracted from the phase difference φb. A temperature-dependent phase difference Δφb based on the temperature displacement is calculated.

  Next, the process proceeds to step S3, the temperature T is calculated with reference to the temperature calculation map stored in the storage device based on the calculated temperature dependent phase difference Δφb, and then the process proceeds to step S4 to calculate the calculated temperature T Is output to the display device 21 to display the temperature, and then the timer interrupt process is terminated and the process returns to a predetermined main program. The display device 21 displays not only the temperature T of the rotating member 6 but also the axial load and radial load detected in the first to fourth embodiments.

  According to the present embodiment, the spindle device of the machine tool is stopped, and the rotating member 6 is assumed to be substantially equal to the temperature in the room where the machine tool is installed. Since the rotating member 6 is stopped in the stopped state of the spindle device, no sine wave signal is output from the rotation sensors 4 and 40, and the rotation sensors 4 and 40 and the spacers 2b and 2d with the annular encoder function are not connected. A DC signal of a level corresponding to the facing position is output. In this state, since the phase differences φa and φb are not output, the control device 20 stops the temperature detection process.

  When the spindle device is stopped and a rotary tool 6 is mounted with a tool such as a drill and rotation driving is started, the rotary member 6 is in an almost unloaded state until the tool comes into contact with the workpiece. Is driven to rotate. Therefore, the rotation sensors 4 and 40 output phase differences φa0 and φb0 representing the initial load “0”. By supplying these phase differences φa0 and φb0 to the control device 20, the control device 20 starts executing the temperature control process shown in FIG.

  When the phase differences φa and φb of the rotation sensors 4 and 40 are read (step S1), the temperature of the rotating member 6 is substantially equal to room temperature, and the spacers 2b and 2d with the annular encoder function of the rotating member 6 are used. The length between them is the length according to the room temperature. For this reason, the phase difference φa detected by the rotation sensor 4 does not include a temperature-dependent component, and the phase difference φb detected by the rotation sensor 40 includes a temperature-dependent phase difference Δφb. The temperature dependent phase difference Δφb can be calculated by subtracting the phase difference φa from φb (step S2).

Then, the temperature T of the rotating member 6 is calculated by referring to the temperature calculation map shown in FIG. 14 based on the calculated temperature-dependent phase difference Δφb (step S3), and the calculated temperature T is displayed on the display device 21. The
From this state, when machining is started by bringing the tool into contact with the workpiece, an axial load is input to the rotating member 6 via the tool. Thus, when an axial load is input to the rotating member 6, the rotating member 6 is displaced in the axial direction in response to this, and the phase differences φa0 and φb0 in the initial state are detected from the rotation sensors 4 and 40 according to this displacement. On the other hand, phase differences φa and φb having large values are output.

  However, since the load displacement due to the axial load is applied to the rotating member 6, the spacers 2 b and 2 d with the annular encoder function are equally displaced, and the axial load can be detected based on the phase difference φa of the rotation sensor 4. In addition, by subtracting the phase difference φa of the rotation sensor 4 from the phase difference φb of the rotation sensor 40, the true temperature-dependent phase difference Δφb from which the load displacement due to the axial load is removed can be calculated. The temperature T can be calculated by referring to the temperature calculation map based on Δφb. The temperature of the spindle device will rise as machining with the tool proceeds, but the temperature at this time can be accurately detected. Moreover, since the detected temperature T, the axial load, and the radial load are displayed on the display device 21, the operator can accurately grasp the machining status.

In the fifth embodiment, the case where the rotating member 4 and the stationary member 7 are the same as those in the first to fourth embodiments has been described. However, the present invention is not limited to this. 16, the rotary member 6 is rotatably supported by two bearings 1a and 1b, and a spacer 2a with an annular encoder function is disposed between the bearings 1a and 1b. Opposite the function-provided spacer 2a, the rotation sensor 4 is supported by the sensor casing 5, and the rotation member 6 is spaced from the spacer 2a with the annular encoder function by a predetermined distance 2d. A ring 60 with an annular encoder function having the same configuration is integrally attached by fixing means such as press-fitting and nut fastening, and the rotation sensor 40 is placed at a position facing the ring 60 with an annular encoder function. The temperature of the rotating member 6 can be detected based on the phase differences φa and φb of the rotation sensors 4 and 40 even if supported by the sensor housing 50, and is the same as in the fifth embodiment described above. An effect can be obtained. Even in this case, the axial load F transmitted to the rotating member 6 is transmitted to the stationary member 7 via the bearings 1 a and 1 b and supported by the stationary member 7. Similarly, the spacer 2d with an annular encoder function in the fifth embodiment can be replaced with a ring similar to the ring 60 with an annular encoder function.
Moreover, also in the said 1st-4th embodiment, the number of the bearings which rotatably supports the rotation member 6 is not limited to four pieces, It can be made into two or more arbitrary numbers.

  1a to 1e are bearings, 2a to 2d are spacers, 3 is a V groove, 3a and 3b are oblique portions, 4 is a rotation sensor, 5 is a sensor housing, 5a is a large-diameter base, 5b is a rod-shaped portion, and 6 is a rotation. Member, 7 stationary member, 8 support tool, 9 fixing tool, 10 mold, 11 positioning pin, 19 signal cable, 20 control device, 21 display device, 40 rotation sensor, 50 sensor housing Body, 60 is a ring with an annular encoder function

Claims (15)

  In a bearing assembly using a plurality of bearings, two rows of annular encoders having different circumferential boundary characteristics are installed on the rotating member between the plurality of bearings, and two rows of circumferential boundary characteristics different from each other of the annular encoder. At least two or more rotation sensors for detecting each of the rotation sensors are installed on the stationary member, and the change of the phase difference between the pulse signals of the two different circumferential boundary characteristics of the annular encoder detected by the rotation sensor is detected. A bearing assembly, wherein a rotation sensor is fixed to a tip of a rod-like portion of a sensor casing, and the sensor casing is fixed to a stationary member.   In a bearing assembly using a plurality of bearings, a plurality of annular encoders having different circumferential boundary characteristics in two rows are installed on the rotating member between the plurality of bearings and at positions spaced apart from each other by a predetermined distance. At least four or more rotation sensors for detecting two different circumferential boundary characteristics of the annular encoder are installed in the stationary member, and two circumferential boundary characteristics of the annular encoder detected by the respective rotation sensors are different. A bearing assembly characterized by detecting a change in a phase difference of a pulse signal, fixing each rotation sensor to a tip of a rod-like portion of an individual sensor casing, and fixing the sensor casing to a stationary member.   The bearing assembly according to claim 1, wherein a load acting on the rotating member is calculated by calculation from a change in phase difference of the detected pulse signal.   The bearing assembly according to claim 2, wherein the temperature of the rotating member is calculated by calculation from a change in phase difference of the pulse signal detected by each rotation sensor.   2. The boundary characteristic of at least one of the two circumferential boundary characteristics of the annular encoder is gradually shifted in the axial direction as the annular encoder rotates. The bearing assembly as described in any one of thru | or 4.   6. Two rotation sensors are arranged at different positions in the axial direction of the rotating member and at the same position in the circumferential direction or at positions shifted in the circumferential direction. A bearing assembly according to 1.   The bearing assembly according to any one of claims 1 to 6, wherein a plurality of the rotation sensors are arranged in a circumferential direction of the rotating member.   The bearing assembly according to any one of claims 1 to 7, wherein the sensor housing is fixed to a stationary member while being shifted from a central axis of the annular encoder in a cross section orthogonal to the axis of the rotating member.   The bearing assembly according to any one of claims 1 to 8, wherein a rod-shaped portion of the sensor casing is formed in a bifurcated shape, and a rotation sensor is fixed to each of the bifurcated rod-shaped portion.   The bearing assembly according to any one of claims 1 to 9, wherein a front surface of the rod-like portion of the sensor casing and a surface on which the rotation sensor is fixed are an ellipse, an ellipse, or a rectangle.   The bearing assembly according to any one of claims 1 to 10, wherein the sensor housing is fixed to a stationary member with a separate support and fixing tool.   The bearing assembly according to claim 1, wherein a positioning member is interposed between the sensor housing and the stationary member.   The bearing assembly according to any one of claims 1 to 12, wherein when a plurality of bearings are arranged side by side to support the rotating member, a rotation sensor is disposed at the center of the plurality of bearings.   The bearing assembly according to any one of claims 1 to 13, wherein a signal cable from a rotation sensor is inserted into a pipe formed in advance in the stationary member.   The bearing assembly according to any one of claims 1 to 14, wherein two or more annular encoders having different numbers of generated pulses per unit rotation are installed on a common rotating member.

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