JP2010216654A - 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 different in two rows) 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 of the spacer 2b with the annular encoder function detected by the 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 can be provided in the spacer 2b between the bearings 1b, 1c so as to be suitable for the machine tool. <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. This is necessary and further increases the cost.

  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.

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 number of pulses generated by the rotation sensor based on the circumferential boundary characteristics of the annular encoder is set to a value different from an integral multiple of a load fluctuation period input to the rotating member. is there.

Further, the number of cutting blades of the cutting tool attached to the rotating member is set to be different from an integer multiple of the number of pulses generated by the rotation sensor based on the circumferential boundary characteristics of the annular encoder. It is characterized by that.
Further, among the two different circumferential boundary characteristics of the annular encoder, at least one of the annular encoders is characterized in that the boundary characteristics change obliquely in the axial direction as the annular encoder rotates. It is.

Further, two combinations of the annular encoder and the rotation sensor are arranged in the axial direction or substantially in the axial direction of the rotating member.
Further, a plurality of combinations of the annular encoder and the rotation sensor are arranged in the circumferential direction of the rotating member.
The annular encoder is characterized in that grooves or projections are formed in the spacers between a plurality of bearings to provide the two rows of different circumferential boundary characteristics.

The annular encoder is characterized in that two rows of encoder rings having different circumferential boundary characteristics are attached to the spacers between a plurality of bearings.
Further, the two circumferential boundary characteristics of the annular encoder are arranged apart from each other in the axial direction of the rotating member.
Further, a rotation restricting member is interposed between the rotating member and the annular encoder.
Further, the phases of the two circumferential boundary characteristics of the two annular encoders are shifted in the circumferential direction.

  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 in the spacer, it can be suitably used for a machine tool.

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.
In addition, the number of load fluctuations per rotation input to the rotating member is set to be different from an integer multiple of the number of pulses generated by the rotation sensor based on the circumferential boundary characteristics of the annular encoder. By doing so, it is possible to eliminate the influence of aliasing in the sampling theorem and perform accurate pulse detection.

In addition, by setting the number of cutting blades of the cutting tool mounted on the rotating member to a value different from an integer multiple of the number of pulses generated based on the circumferential boundary characteristics of the annular encoder by the rotation sensor. Thus, accurate pulse detection can be performed by eliminating the influence of aliasing in the sampling theorem.
Also, among the two circumferential boundary characteristics of two different annular encoders, at least one of the circumferential characteristics is such that the boundary characteristics change obliquely in the axial direction as the annular encoder rotates. The boundary characteristics can be easily obtained.

Further, since two combinations of the annular encoder and the rotation sensor are arranged in the axial direction of the rotating member or substantially in the axial direction, the load acting in the axial direction of the rotating member can be obtained by these combinations. it can.
In addition, since a plurality of combinations of the annular encoder and the rotation sensor are arranged in the circumferential direction of the rotating member, a load acting in the radial direction of the rotating member can be obtained by these combinations.

In addition, the annular encoder can easily add the function of the annular encoder to the spacer by forming grooves or protrusions in the spacer between the plurality of bearings to have two different circumferential boundary characteristics. Can be suitably used for machine tools.
In addition, the annular encoder can easily add the function of the annular encoder to the spacer by attaching two rows of encoder rings having different circumferential boundary characteristics to the spacer between the bearings. It can be suitably used for machine tools.

Further, the two circumferential boundary characteristics of the two annular encoders are arranged apart from each other in the axial direction of the rotating member, so that even when the width of the spacer between the two bearings is small, it can be used suitably.
In addition, since a rotation restricting member is interposed between the rotating member and the annular encoder, relative rotation of the annular encoder with respect to the rotating member can be restricted, and two circumferential boundaries between the annular encoders are different. When the characteristics are arranged apart from each other in the axial direction of the rotating member, the phases of the two circumferential boundary characteristics in the two rows can be matched.
In addition, by shifting the phases of the two different circumferential boundary characteristics of the annular encoder in the circumferential direction, the degree of freedom in layout of the rotation sensor is increased.

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 arrangement | positioning explanatory drawing of the circumferential direction of the rotation sensor used for the machine tool of FIG. It is a perspective view which shows the various forms of the spacer with an annular encoder function. It is a perspective view which shows the other form of the spacer with an annular encoder function. It is a perspective view of the rotation control member which controls relative rotation of the spacer with respect to a rotation member. It is a schematic block diagram of the machine tool of FIG. It is a longitudinal cross-sectional view of the machine tool which shows 2nd Embodiment of the bearing assembly of this invention. FIG. 10 is a perspective view of a spacer with an annular encoder function used in the machine tool of FIG. 9. It is a longitudinal cross-sectional view of the machine tool which shows 3rd 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 schematic block diagram of the machine tool which shows 4th 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 longitudinal cross-sectional view of the machine tool which shows 5th Embodiment of the bearing assembly of this invention. It is a longitudinal cross-sectional view of the machine tool which shows 6th Embodiment of the bearing assembly of this invention. It is a time chart which shows the relationship between the load fluctuation waveform input into the rotation member of 6th Embodiment, and a load detection value.

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 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.

  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 V-shaped groove 3 having a tapered tip at the center in the width direction is formed in the same 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. 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 rotation sensor described above, the rotation sensor 4 has a configuration in which a permanent magnet magnetized in a V shape is disposed facing a hall element as described in, for example, JP-A-2006-317420. It is also possible to use an active type rotation sensor. In the present invention, various forms of rotation sensors can be applied. 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 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. Of course, a function other than the sensor may be provided with a function of converting to a pulse signal. The sensor housing 5 includes a small-diameter portion 5b that holds the rotation sensor 4 at the tip portion, and a large-diameter portion 5a that is connected to the rear end portion of the small-diameter portion 5b. The large-diameter portion 5a includes the sensor housing 5 Is provided with a recess 5c for fixing to the stationary member 7. The support 8 is housed in the recess 5c, and the support 8 is fixed to the stationary member 7 with a fixing tool 9 such as a bolt. 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, so that the rotational sensor 4 is slightly in the axial direction of the rotating member 6. It's off. The shift in the axial direction of the rotation sensor 4 is a shift in the circumferential direction of the spacer 2b with an annular encoder function. The reason will be described later.

In the present embodiment, as shown in FIG. 4, 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. That is, when a load in the axial direction or radial direction is applied to the rotating member 6, the time difference between the detected pulses on the time axis of two rows to be detected, that is, the phase difference between the two detection pulses is changed. 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.

  FIG. 5 shows two additional rows of different circumferential boundary characteristic configurations. FIG. 5 a is similar to the V-groove 3 of FIG. 2, but the end of the V-groove 3 is not passed through the end of the spacer 2 b in the width direction. That is, the thickness of the spacer 2b (the length in the radial direction) is also secured in the V groove 3 portion. The spacer is for regulating the dimension between the bearings, and also for ensuring the preload of the bearings, so the thickness is important. The thickness of the spacer 2b can be ensured by preventing the V groove 3 from penetrating through the end in the width direction.

5b, as in FIG. 5a, not only does not allow the two oblique portions 3a and 3b of the V-groove to pass through the end portion in the width direction of the spacer 2b, but also does not connect the V-groove and divides it at the central portion. Thus, only the oblique portions 3a and 3b were formed. Since the detection targets are the oblique portions 3a and 3b as described above, that is, the portions with two different circumferential boundary characteristics, it is not necessary to connect the V grooves.
Figure 5 c forms a large diameter portion 2ba and a small diameter portion 2bb between seat 2b, the respectively, to form an oblique portion 3a, 3b of the V-groove. As a result, the V-groove is not connected. In this embodiment, when the outer diameters of the bearings on both sides of the spacer 2b are different or the types of the bearings are different, for example, the bearing arranged on the right side of the figure is a radial bearing, and the bearing arranged on the left side is This is suitable for an axial bearing. Further, in this case, it is necessary to set the position of the rotation sensor so as to face the respective oblique portions 3a and 3b.

  5d, similarly to FIG. 7c, a large diameter portion 2ba and a small diameter portion 2bb are formed in the spacer 2b, and only the other oblique portion 3b of the V-groove is formed in the small diameter portion 2bb (that is, “ V "character does not appear). On the other hand, in the large-diameter portion 2ba, radial grooves 12 facing the oblique portion 3b are formed on the end surface in the axial direction on the small-diameter portion 2bb side. Also in this case, it is necessary to set the position of the rotation sensor so as to face the oblique portion 3b and the groove 12. In the case of this embodiment, even if a load is applied in the axial direction of a rotating member (not shown), no phase shift occurs in the detection pulse of the groove 12. In contrast, when an axial load is applied to the rotating member, a phase shift occurs in the detection pulse of the oblique portion 3b. Accordingly, it is possible to detect a change in the phase difference of the detection pulse in the oblique portion 3b with reference to the detection pulse in the groove 12, and calculate the load from the change in the phase difference.

  FIG. 6 shows another two rows of different boundary characteristic configurations. In this embodiment, the two oblique portions 3a and 3b of the V-groove to be formed on the outer peripheral surface of the spacer 2b are formed by shifting the phase by half the pitch of the original V-groove (that is, the “V” character is Does not appear). 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. When detecting the change in the phase difference of this detection pulse, the absolute phase of the annular encoder is not set to detect whichever pulse occurs first and to detect the phase difference from the preceding pulse to the subsequent pulse. However, even if the absolute phase is set, it is not practical because it only increases the capacity and calculation load of the memory and counter.

  Therefore, in general, as inferred from the embodiment of FIG. 5d, the time until the other detection pulse is reached is measured using either one of the detection pulses as a reference. 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. On the other hand, as shown in FIG. 6, when the two oblique portions 3a and 3b are formed by shifting the phase by half the original pitch of the V-groove, for example, the rotation sensor 4 is displaced in the circumferential direction of the spacer 2b. Even if the rotating member is correctly aligned in the axial direction, the detection pulse is shifted by “0.5” pulse wavelength from the beginning. Therefore, the phase difference from the initial value may be detected as a change in the phase difference between the two detection pulses.

  In addition, when attaching the spacer 2b with an annular encoder function to the rotating member 6, as shown in FIG. 7, for example, the key groove 10 is formed on the inner periphery of the spacer 2b with the annular encoder function and the outer periphery of the rotating member 6. Alternatively, the key 11 may be inserted into the key groove 10 to restrict the relative rotation of the spacer 2b with annular encoder function with respect to the rotating member 6. By the way, when the relative rotation of the spacer with the annular encoder function is restricted by a rotation restricting member such as a key, the circumferential boundary characteristics of two rows of the annular encoder, specifically, the annular encoder, as will be described later, When the function-equipped spacers are arranged apart from each other in the axial direction of the rotating member, the phases of the circumferential boundary characteristics can be matched. In addition to the key, any known rotation regulating member can be applied to the rotation regulating member.

  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.

  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. It can be used suitably.

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.
In addition, among the two different circumferential boundary characteristics of the spacer 2b with the annular encoder function, at least one of the circumferential boundary characteristics is inclined such that the boundary characteristic is obliquely changed in the axial direction in accordance with the rotation of the annular encoder function 2b. Since the portions 3a and 3b are used, different circumferential boundary characteristics can be easily obtained.

In addition, since two combinations of the spacer 2b with the annular encoder function and the rotation sensor 4 are arranged in the axial direction of the rotating member 6 or substantially in the axial direction, the axial direction of the rotating member 6 is determined by these combinations. A load acting in the (axial direction) can be obtained.
In addition, since a plurality of combinations of the spacer 2b with the annular encoder function and the rotation sensor 4 are arranged in the circumferential direction of the rotating member 6, the equal pressure direction (radial direction) of the rotating member 6 is determined by these combinations. ) Can be obtained.

In addition, the annular encoder is formed by forming a V groove (or V-shaped projection) 3 in the spacer 2b between the two bearings 1b and 1c to provide two rows of different circumferential boundary characteristics. It is possible to easily add the function of the annular encoder to the machine tool.
In addition, since the rotation restricting member 11 is interposed between the rotating member 6 and the spacer 2b with the annular encoder function, relative rotation of the spacer 2b with the annular encoder function with respect to the rotating member 6 can be restricted. Further, by shifting the phases of the two oblique portions (two rows of different circumferential boundary characteristics) 3a and 3b of the spacer 2b with an annular encoder function in the circumferential direction, the degree of freedom in layout of the rotation sensor 4 is increased.

Next, 2nd Embodiment of the bearing assembly of this invention is described using FIG. 9, 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. 1 of the first embodiment, and the same components are denoted by the same reference numerals, and the detailed description thereof will be given. Omitted. In the present embodiment, instead of directly adding the annular encoder function to the spacer 2b between the two bearings 1b and 1c, the encoder ring 13 to which the annular encoder function has been added in advance is fitted onto the spacer 2b. The encoder ring 13 has a small-diameter portion 13a that fits tightly into the outer peripheral surface of the spacer 2b and a small gap formed between the small-diameter portion 13a and the outer peripheral surface of the spacer 2b. is configured to include a large diameter portion 13b covering the surface, in the large-diameter portion 13 b, as in the first embodiment, the two oblique parts 3a, the V groove 3 with 3b are opened.

  The encoder ring 13 can be formed non-cut by, for example, pressing. Therefore, if the encoder ring 13 is formed in advance and the encoder ring 13 is tightly fitted to the spacer 2b having the same outer diameter to add an annular encoder function, a cutting process is not required. Moreover, since the spacer 2b is not cut, the strength of the spacer can be ensured.

  Next, 3rd Embodiment of the bearing assembly of this invention is described using FIG. 11, 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. 1 of the first embodiment, and the same components are denoted by the same reference numerals, and the detailed description thereof will be given. Omitted. In the present embodiment, instead of directly adding the annular encoder function to the spacer 2b between the two bearings 1b and 1c, the encoder ring 13 to which the annular encoder function has been added in advance is fitted onto the spacer 2b. The encoder ring 13 has a small-diameter portion 13a that fits tightly into the outer peripheral surface of the spacer 2b and a small gap formed between the small-diameter portion 13a and the outer peripheral surface of the spacer 2b. A large-diameter portion 13b that covers the surface and a multi-pole magnet encoder 14 fitted to the large-diameter portion 13b are provided.

  This multi-pole magnet type encoder 14 has a ring shape in which V-shaped thin V-type S poles 14S are alternately arranged in the circumferential direction in the same manner as the V-shaped thin V-type N-pole 14N. The rotation sensor 4 detects the two oblique portions of the V-type N pole 14N and the V-type S pole 14S as two different circumferential boundary characteristics, and calculates a sinusoidal current value generated by the approach and separation thereof to a predetermined threshold value. Turns on and off to output a pulse signal. Unlike the rotation sensor 4 of the first and second embodiments, the encoder 14 side has a magnetic force, so no magnetic force is required on the rotation sensor 4 side.

The encoder ring 13 can be formed non-cut by, for example, pressing. Therefore, an encoder ring 13 having a multipole magnet type encoder 14 fitted on the outer periphery is formed in advance, and the encoder ring 13 is tightly fitted on the same outer diameter spacer 2b so as to add an annular encoder function. If so, the cutting step is not required as in the second embodiment. Moreover, since the spacer 2b is not cut, the strength of the spacer can be ensured.
As described above, in the bearing assembly of this embodiment, the encoder ring 13 having two different circumferential boundary characteristics is attached to the spacer 2b between the two bearings 1b and 1c. The function of the annular encoder can be easily added and can be suitably used for a machine tool.

  Next, 4th Embodiment of the bearing assembly of this invention is described using FIG. 13, FIG. The spindle device of the machine tool to which the bearing assembly of this embodiment is applied is similar to that of FIG. 8 of the first embodiment, and the same components are denoted by the same reference numerals, and the detailed description thereof will be given. Omitted. In the present embodiment, the control device is not shown. In the first and second embodiments, two rows of different circumferential boundary characteristics are given to the spacer 2b between the two bearings 1b and 1c. However, in this embodiment, the gap between the bearings 1a and 1b is given. Different circumferential boundary characteristics are imparted to the spacer 2c between the seat 2a and the bearing 2c between the bearings 1c and 1d, and two circumferential spacers 2a and 2c spaced apart in the axial direction of the rotating member 6 are arranged in two rows. Get properties. The rotation sensor 4 and the sensor housing 5 that holds the rotation sensor 4 are disposed so as to face the two spacers 2a and 2c. Note that only one rotation sensor 4 is mounted on the sensor housing 5. Also in this embodiment, a plurality of pairs of combinations of the rotation sensor 4 spaced apart in the axial direction of the rotating member 6 and two rows of different circumferential boundary characteristics are arranged in the circumferential direction of the rotating member 6. I do not care.

  The distance between adjacent bearings of the plurality of bearings 1a to 1d is short, and the widths (length in the axial direction) of the spacers 2a to 2c are also short. It may be difficult to arrange the V-groove 3, V-type N pole 14N, and V-type S pole 14S as in the first and second embodiments in any of the narrow spacers 2a to 2c. is there. Further, the rotation sensor 4 must be disposed so as to face, for example, the two oblique portions 3a and 3b of the V-groove 3. However, since the distance between the bearings is short, there is a possibility that they cannot be disposed properly. is there. In such a case, as in the present embodiment, each of the two spacers 2a and 2c is provided with one oblique portion 3a and 3b constituting the V groove, and each is detected by the rotation sensor 4. By doing so, it is possible to cope with a case where the distance between the bearings is short. In such a case, two spacers 2a, 2c, that is, two oblique portions 3a, are provided by interposing a rotation restricting member such as a key between the spacers 2a, 2c and the rotating member 6. The phase of 3b can be made into an appropriate state.

  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 this embodiment is applied is similar to that of FIG. 8 of the first embodiment, and the same components are denoted by the same reference numerals, and the detailed description thereof will be given. Omitted. In the present embodiment, the control device is not shown. In the present embodiment, as in the fourth embodiment, the spacers 2a and 2c that are separated in the axial direction of the rotating member 6 are provided with the inclined portions 3a and 3b that constitute the V-grooves, and these spacers 2a. 2c, the diagonal portions 3a and 3b are detected by the individual rotation sensors 4. In the fourth embodiment, the sensor housing 5 that holds these rotation sensors 4 is a separate body. In the present embodiment, the small diameter portion 5b that holds the rotation sensor 4 itself is a separate body. The base portion of the small diameter portion 5b is connected by the connecting portion 5c, and the sensor housing 5 is integrated.

As described above, since the paired rotation sensors 4 are for detecting a change in the phase difference between the two detected pulses, the two circumferential boundary characteristics of the two rows are the same. The phases of the two rotation sensors 4 must be in an appropriate state. As in the fourth embodiment, when the sensor housing 5 that holds the rotation sensor 4 is a separate body, it is necessary to separately use means for regulating the fixed state of the two sensor housings 5. If the body 5 is integrated, it is not necessary to take such a regulation means.
As described above, in the bearing assembly of the present embodiment, the two circumferential boundary characteristics of the two annular encoders are arranged apart from each other in the axial direction of the rotating member 6, thereby reducing the width of the spacer between the two bearings. Even if it is small, it can be suitably used.

Next, a sixth embodiment of the bearing assembly of the present invention will be described with reference to FIGS. The spindle device of the machine tool to which the bearing assembly of this embodiment is applied is similar to that of FIG. 8 of the first embodiment, and the same components are denoted by the same reference numerals, and the detailed description thereof will be given. If you omit.
In the sixth embodiment, a cutting tool 40 such as a drill is attached to the rotating member 6 constituting the spindle device of the machine tool to cut the workpiece.

  In such a spindle device of a machine tool, the rotational speed of the rotary member 6 on which the cutting tool 40 is mounted is increased. Therefore, when considering the processing speed of the calculator that inputs the pulse signal output from the rotation sensor 4, The number of V-grooves of the annular encoder 2b, that is, the number of pulses n per rotation of the rotating member 6 output from one rotation sensor 4 is about a dozen at most in a single digit. Set less than the number of teeth.

Then, when the workpiece of the cutting tool 40 is processed, the number of blades of the cutting tool that causes a load fluctuation input to the rotating member 6 per rotation of the rotating member 6 is m, and the number of V grooves of the annular encoder 2b, that is, rotation. When the number of pulses per rotation of the rotating member 6 output from the sensor 4 is n, the number m of cutting blades of the cutting tool is an integer of the number of pulses n per rotation of the rotating member 6 output from the rotation sensor 4. The value is set to be different from the double (m ≠ an a is an arbitrary integer). That is, assuming that the number m of cutting blades per rotation of the cutting tool 40 is 10, for example, 1 , 2 and 5 in which the integer multiple of the V groove number n of the V groove 3 of the annular encoder 2b is 10. The value to be excluded is set to 7, for example.

  Thus, the number of V grooves 3 of the annular encoder 2b is set to a value different from the integer of the number n of pulses per rotation of the rotating member 6 output from the rotation sensor 4 by the number m of cutting blades of the cutting tool 40. The reason for setting is that when the number m of cutting blades per rotation of the cutting tool 40 is 10, the load fluctuation occurs 10 times for one rotation of the rotating member 6. At this time, if the number of V grooves n of the annular encoder 2b is set to 10, for example, the number of pulse signals output from one rotation sensor 4 per rotation of the rotating member 6 becomes 10 pulses, and the cutting tool 40 The number m of cutting blades is equal to one time the number of pulses n of the pulse signal per rotation of the rotating member 6 output from the rotation sensor 4.

  At this time, the fluctuating load generated during machining by the cutting tool 40 has a waveform like a sine wave that vibrates 10 times in one rotation of the rotating member 6 as shown by a characteristic curve L1 in FIG. At this time, when the number of V grooves of the annular encoder 2b is 10 and the number of pulses n per rotation of the rotating member 6 detected by the rotation sensor 4 is n = 10, the number of pulses detected by the rotation sensor 4 is increased. The load detection value calculated on the basis can be sampled 10 times per rotation as indicated by ● in FIG. As is clear from FIG. 17, the load detection value represented by ● has a phenomenon in which an offset of a DC (direct current) component is generated compared to the actual load average value indicated by a thick solid line, and the load cannot be accurately detected. appear.

Such a phenomenon occurs when the number m of cutting blades of the cutting tool 40 is equal to the number of V grooves of the annular encoder 2b, that is, the number of pulses n output from one rotation sensor 4 per one rotation of the rotating member 6. When it becomes an integral multiple. This phenomenon can be considered that a load variation component is added as a DC component due to the influence of the sampling theorem (aliasing).
Therefore, the number of V grooves of the annular encoder 2b, that is, the number of pulses n per rotation of the rotating member 6 output from the rotation sensor 4 is set to a value in which the integral multiple does not match the number m of cutting blades of the cutting tool 40. Thus, the influence of the sampling theorem (aliasing) can be avoided and accurate load detection can be performed.

  In the sixth embodiment, the number m of cutting blades of the cutting tool 40 is 10, and the number of pulses per one rotation of the rotating member 6 output from the rotation sensor 4 according to the number of V grooves of the annular encoder 2b. However, the present invention is not limited to this. In short, the number m of blades of the cutting tool 40 is set to the number n of pulses per one rotation of the rotating member 6 output from the rotation sensor 4. What is necessary is just to set so that it may become a value different from the integer multiple of.

Moreover, as the cutting tool 40, it is not limited to a drill, Arbitrary tools, such as a milling cutting tooth, can be applied.
Moreover, in the said 6th Embodiment, although the case where the cutting tool 40 was mounted | worn with the rotating member 6 was demonstrated, it is not limited to this, It is not limited to this but the period per rotation of the rotating member 6 not only to the cutting tool 40. When the axial load fluctuation is applied, the axial load fluctuation number per rotation of the rotating member 6 is an integral multiple of the number of pulses per rotation of the rotating member 6 output from the rotation sensor 4. May be set to have different values.

  1a to 1d are bearings, 2a to 2c are spacers, 3 is a V groove, 3a and 3b are oblique portions, 4 is a rotation sensor, 5 is a sensor housing, 6 is a rotating member, 7 is a stationary member, and 8 is a support. , 9 is a fixture, 10 is a keyway, 11 is a key, 12 is a groove, 13 is an encoder ring, 14 is a multi-pole magnet encoder, 15 is a cage, 19 is a signal cable, and 20 is a control device.

Claims (12)

  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 the rotation of the annular encoder are installed on the stationary member, and the change in the phase difference between the pulse signals of the two circumferential boundary characteristics of the two annular encoders detected by the rotation sensor is detected. Bearing assembly.   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 number of load fluctuations per rotation input to the rotating member is set to be different from an integer multiple of the number of pulses generated by the rotation sensor based on the circumferential boundary characteristics of the annular encoder. The bearing assembly according to claim 1 or 2.   The number of cutting blades of the cutting tool attached to the rotating member is set to be different from an integer multiple of the number of pulses generated by the rotation sensor based on the circumferential boundary characteristics of the annular encoder. The bearing assembly according to claim 1, wherein the bearing assembly is a bearing assembly.   2. The boundary characteristic of at least one of the two circumferential boundary characteristics of the annular encoder changes obliquely in the axial direction with the rotation of the annular encoder. The bearing assembly as described in any one of thru | or 4.   5. The bearing assembly according to claim 1, wherein two sets of the annular encoder and the rotation sensor are arranged in the axial direction or substantially in the axial direction of the rotating member.   The bearing assembly according to claim 1, wherein a plurality of combinations of the annular encoder and the rotation sensor are arranged in a circumferential direction of the rotating member.   8. The annular encoder according to claim 1, wherein grooves or protrusions are formed in the spacers between a plurality of bearings to provide the two rows of different circumferential boundary characteristics. 9. The bearing assembly according to item.   8. The annular encoder according to claim 1, wherein two rows of encoder rings having different circumferential boundary characteristics are attached to a spacer between a plurality of bearings. 9. Bearing assembly.   The bearing assembly according to any one of claims 1 to 8, wherein two circumferential boundary characteristics of the annular encoders are arranged apart from each other in the axial direction of the rotating member.   The bearing assembly according to any one of claims 1 to 9, wherein a rotation restricting member is interposed between the rotating member and the annular encoder.   11. The bearing assembly according to claim 1, wherein phases of different circumferential boundary characteristics of two rows of the annular encoder are shifted in the circumferential direction.

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