JPH06207621A - Fixed flow rate controlling under race lubricating spindle device - Google Patents

Abstract

PURPOSE:To stabilize spindle performance by providing a flow rate sensor in an oil sending piping of lubricating oil to be sent to a spindle shaft, and controlling the flow rate of the lubricating oil by means of an output signal of the flow rate sensor. CONSTITUTION:A flow rate sensor 28 detects the flow rate of lubricating oil passing through an oil sending piping 29 and outputs a flow rate signal. This flow rate signal is input into a controller 30. The controller 30 controls the opening of a control valve 27 so that the flow rate of lubricating oil passing through the oil sending piping 29 may become the preset flow rate value, and makes the amount of lubricating oil to enter into a draw bar 8 always to a constant value. Thereby, even if the state change of the number of revolutions of a spindle shaft 1 is generated, the supply amount of lubricating oil to a spindle device can be always maintained constant, and fluctuation of the temperature rise and the consumed power can be restrained, moreover spindle performance can be stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underlace lubrication spindle device for supplying lubricating oil from the center of a spindle shaft to a bearing inner ring that supports the spindle shaft, and more particularly to lubricating oil even when the rotational speed of the spindle shaft is changed. Constant-flow control under-race lubrication spindle device capable of maintaining a constant flow rate.

[0002]

2. Description of the Related Art Conventionally, as a lubrication system for a high-speed spindle device that supports a tool spindle (spindle shaft) of a machining center, there is a jet lubrication system in which a large amount of lubricating oil is injected from a nozzle on the side of the bearing toward the inside of the bearing. In this jet lubrication system, the lubricating oil has a large stirring resistance and the shaft is not sufficiently cooled.Therefore, in a spindle device at an even higher speed than this, the lubricating oil is supplied to the inner ring of the bearing not through the outside of the bearing but through the spindle shaft. The so-called underlace lubrication method is adopted.

As an ultra-high-speed machining center spindle device adopting an under-race lubrication system, for example, Japanese Utility Model Laid-Open No. 4-57355 or Japanese Patent Application No. 4-3110.
There is a spindle device described in Japanese Patent Publication No. 34-34. This is because a lubricating oil supply intermediate sleeve, in which a tool fixing / releasing rod called a draw bar is inserted in the through hole of a hollow spindle shaft, is arranged at the center of the shaft according to the position corresponding to the bearing. Circumferential oil grooves are provided on the outer surface, respectively, and radial oil passages are provided so as to connect these oil grooves, and further, the circumferential oil groove on the sleeve outer surface side and the radial oil supply hole formed on the bearing inner ring are formed. The spindle shaft is communicated with a radial oil passage, and the oil groove on the inner surface of the intermediate sleeve is communicated with the oil passage extending in the axial direction of the draw bar, and is passed through a rotary joint at the shaft end of the spindle shaft. Lubricating oil is supplied from an external oil supply pump.

[0004]

The underlace lubrication spindle device is excellent for high speed rotation because the bearing inner ring can be cooled from the spindle shaft side. In this case, the lubricating oil is in the lubricating oil passage in the spindle device. Is pumped from the supply pump in a state of being filled with the oil, and as described above, the lubricating oil is introduced from the central drawbar to the inner ring through the intermediate sleeve and the radial oil passage in the spindle shaft, and therefore, due to the high speed rotation of the spindle shaft. When the centrifugal force acts on the lubricating oil in the shaft and the number of rotations increases, the pipeline resistance of the lubricating oil changes, the supply amount of the lubricating oil fluctuates, and the flow rate from the supply pump increases. On the contrary, if the amount of lubricating oil is too large, the rotational resistance of the bearing increases, which causes an increase in power consumption due to an increase in load of the spindle drive motor, and there is a problem that spindle performance such as temperature rise is affected.

According to the present invention, the amount of lubricating oil supplied to the apparatus can always be kept constant even if the state of rotation of the spindle shaft changes, thereby stabilizing the spindle performance such as temperature rise and power consumption. An object of the present invention is to provide an underlaced lubrication spindle device.

[0006]

According to the present invention, a spindle shaft is rotatably supported by a rolling bearing fitted in a housing, and lubricating oil is applied to the bearing from the inner ring side of the rolling bearing through the spindle shaft. An under-race lubrication spindle device for supplying, wherein the spindle shaft has a hollow hole, through which a drawbar for tool removal is inserted through an intermediate sleeve, and a lubricating oil supply passage is provided at the center of the drawbar. A rotary joint is provided at a rear end portion of the drawbar, the lubricating oil is supplied from the cooling unit to the lubricant oil supply passage of the drawbar through the rotary joint, and further the lubricant oil is supplied from the lubricant oil supply passage to the intermediate sleeve. Lubricating oil should be supplied to the inner ring of the rolling bearing from the radial lubricating oil supply hole provided in the spindle shaft through the provided radial hole. And a constant flow rate control under-race lubrication spindle device having a flow rate sensor provided in the lubricating oil flow path on the outlet side of the cooling unit and a controller for controlling the flow rate of the lubricating oil to be substantially constant by a detection signal of the flow rate sensor. Is obtained.

[0007]

The lubricating oil is pumped from the rear end side into the draw bar of the spindle device by the supply pump, and the amount of the lubricating oil from the cooling unit increases when the duct resistance in the device decreases due to centrifugal force or the like. Detects the amount of lubricating oil with a flow rate sensor provided on the outlet side of the cooling unit on the oil sending side, inputs this detection signal to the controller, and even if the line resistance changes when the rotational speed of the spindle shaft changes. The control valve and the drive motor of the supply pump are controlled so that the supplied oil amount is always the set flow rate required for the spindle shaft, so the supplied lubricating oil amount is kept constant even if there is a fluctuation in the rotational speed of the spindle shaft. be able to.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. On the spindle device side, a hollow spindle shaft 1 is rotatably supported in a cylindrical housing 2 via two rolling bearings 3 in each of the front and rear portions, and a taper hole 10 formed in the front end portion of the spindle shaft 1 is provided. The shaft portion of the tool 24 is inserted into and held by. The spindle shaft 1 has a lubricating oil supply hole 13 bored in a radial direction at a position corresponding to each bearing 3, and an inner ring of each bearing 3 is provided with a radial oil supply hole 6. Two intermediate sleeves 7 corresponding to the two front bearings 3 and the two rear bearings 3 are inserted into the hollow holes of the spindle shaft 1, and the spindle shaft 1 can be moved back and forth. The drawbar 8 is inserted. The rear end of the drawbar 8 projects from the spindle shaft 1 and is connected to the rotary joint 9.

The draw bar 8 has a lubricating oil supply passage 11 formed along its axis, which is a dead end near the front end. The lubricating oil supply passage 11 extends to the rear end of the drawbar, communicates with the lubricating oil introduction hole of the rotary joint 9, and opens from the radial branch hole 12 in the drawbar 8 to the axial groove and the circumferential groove on the outer periphery of the drawbar. ing. The circumferential groove on the outer periphery of the drawbar further passes through the radial hole of the intermediate sleeve 7 and the circumferential groove 4 on the outer periphery of the sleeve to the radial lubricating oil supply hole 13 formed in the spindle shaft 1 to supply the radial oil to each bearing inner ring. Therefore, even if the draw bar 8 reciprocates in the axial direction when the tool is attached / detached, the lubricating oil introduced from the rotary joint 9 is used for the draw bar 8, the intermediate sleeve 7, the spindle shaft 1 and the oil supply holes 6 of the bearing inner ring. It is adapted to be supplied to each bearing 3 through. Lubricating oil that lubricates each bearing 3 is provided in the discharge passage 14 formed in the housing 2.
Through the oil drain port 15 at the front end.

In this embodiment, disc springs 16 for pressing the draw bar 8 rearward are provided between the pair of intermediate sleeves 7 and between the intermediate sleeve 7 and the flange portion at the rear end of the draw bar. The front end of the drawbar 8 is formed with a recess 17 so that the neck of the rear end of the tool is inserted, and a ball 19 that engages with a bulge 18 at the end of the neck of the tool is mounted. When the drawbar 8 is pushed rearward with respect to the spindle shaft 1 by the spring force of the disc spring 16, the ball 19 at the front end of the drawbar is surrounded by the intermediate sleeve 7 that surrounds the front end portion of the drawbar.
The bulging portion 18 at the neck end of the tool is locked by being restrained by the inner diameter portion of the tool and the tool 24 is fixed to the spindle shaft 1. The front end of the inner diameter portion of the intermediate sleeve 7 has a large diameter, and therefore the drawbar 8 is resisted against the disc spring 16 and the spindle shaft 1
On the other hand, when the ball 19 is moved forward, the ball 19 drops into the large-diameter inner diameter portion of the front end of the intermediate sleeve 7 and is released from the bulging portion at the neck end of the tool 24 to release the tool 24. Reference numeral 20 is an unclamp lever fixed to the rear end of the drawbar, and when the tool is released, the lever is pushed by a drive device (not shown) to move the drawbar 8 forward.

In the embodiment of FIG. 1, the lubricating oil is forcibly sucked by the oil return pump 22 from the oil discharge port 15 of the housing 2 through the return pipe 21 and returned to the reservoir tank 23. Then, after being pumped up from the tank 23 by the oil feed pump 25 and temperature controlled by the cooling unit 26, the control valve 27 and the flow rate sensor 2 on the outlet side of the unit
After passing through 8, the oil is sent from the rotary joint 9 to the lubricating oil supply passage 11 of the drawbar 8 through the oil supply pipe 29, and is circulated. The flow rate sensor 28 is a sensor that detects the flow rate of the lubricating oil passing through the oil supply pipe 29 and outputs a flow rate signal, and the flow rate signal is input to the controller 30. The controller 30 controls the opening degree of the control valve 27 so that the flow rate of lubricating oil flowing through the oil supply pipe 29 becomes a preset flow rate value. For example, when the rotation speed of the spindle shaft 1 becomes high and the apparent pipeline resistance becomes small due to the centrifugal pump effect of the lubricating oil supply passage in the spindle device and the lubricating oil flow rate through the bearing inner ring increases, the flow sensor 28 When a change is detected, the controller 30 throttles the control valve 27 so that the amount of lubricating oil entering the drawbar 8 is always a constant value. By making the amount of lubricating oil in the spindle device constant in this way, power consumption becomes constant and spindle performance such as temperature rise is stabilized.

FIG. 2 is a lubricating oil control system diagram showing another embodiment of the present invention, in which lubricating oil flows from the return oil pump 22 to the reservoir tank 23, the oil feed pump 25, the cooling unit 26 and the oil feed pipe 29. The route sent to the rotary joint 9 via the flow sensor 28 is the same, but in this embodiment, the controller 30 controls the drive motor 32 of the oil feed pump 25 via the inverter 31 by the detected flow signal from the flow sensor 28. The amount of lubricating oil flowing through the oil supply pipe 29 is controlled to be a preset flow rate. Note that, in the embodiment of FIG. 2, the constituent parts on the spindle device side are the same as those shown in FIG. 1, and the same reference numerals are allotted and duplicate description is omitted.

[0013]

As described above, according to the present invention, a flow rate sensor is provided in the oil feed pipe for the lubricating oil to be sent to the spindle shaft inside the spindle device, and the flow rate of the lubricating oil is controlled by the output signal of the sensor. Therefore, it is possible to reduce changes in the lubricating oil flow rate due to changes in the apparent pipeline resistance on the spindle shaft side by changing the spindle shaft speed, increasing the temperature of the spindle device and increasing the rotation resistance of the bearings. Since it is possible to suppress fluctuations in power consumption of motors and the like, it is possible to stabilize the performance of a machining center in which a large number of tools are replaced and used.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a constant flow rate controlled underrace lubrication spindle device according to one embodiment of the present invention.

FIG. 2 is a schematic view similar to FIG. 1 of another embodiment of the present invention.

[Explanation of symbols]

 1 Spindle Shaft 3 Rolling Bearing 6 Inner Ring Oil Supply Hole 8 Drawbar 9 Rotating Joint 11 Lubricating Oil Supply Passage 13 Lubricating Oil Supply Hole 14 Discharge Passage 15 Exhaust Port 21 Return Pipe 22 Return Oil Pump 23 Reservoir Tank 25 Oil Pump 26 Cooling Unit 27 Control valve 28 Flow rate sensor 29 Oil supply pipe 30 Controller 31 Inverter 32 Drive motor

Claims (1)

[Claims] 1. An underlace lubrication spindle device in which a spindle shaft is rotatably supported by a rolling bearing fitted in a housing, and lubricating oil is supplied to the bearing from the inner ring side of the rolling bearing through the spindle shaft. ,
The spindle shaft has a hollow hole, a drawbar for tool removal is inserted into the hollow hole through an intermediate sleeve, a lubricating oil supply passage is provided at the center of the drawbar, and a rotary end is provided at a rear end portion of the drawbar. A lubricating oil is supplied from a cooling unit to the lubricating oil supply passage of the drawbar through the rotary joint, and the spindle is further provided from the lubricating oil supply passage through a radial hole provided in the intermediate sleeve. Lubricating oil is intended to be supplied to the inner ring of the rolling bearing from a lubricating oil supply hole provided in the shaft in the radial direction, and a flow rate sensor provided in the lubricating oil flow path on the outlet side of the cooling unit and a flow rate sensor of the flow rate sensor. A constant flow rate control under-race lubrication spindle device, comprising: a controller for controlling the flow rate of lubricating oil to be substantially constant according to a detection signal.