JP2521565B2 - Variable oil air lubrication method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-air lubrication method used for a main shaft bearing or the like of a machine tool.

2. Description of the Related Art Conventionally, an oil-air lubrication method used for a main shaft bearing of a machine tool or the like is shown in FIG. 4, in which a pneumatic drive piston pump unit 101 uses a timer 102 that turns on and off at regular intervals. By switching the solenoid valve 103 and intermittently sending air, the pump 101a is intermittently operated, and after adjustment by the mixing valve unit 104, a fixed amount of lubricating oil is mixed with a constant flow rate of air and supplied to the bearing. It is like this. The optimum amount of oil supplied at this time is generally obtained by experiments, and it is common knowledge to set the point A at which the bearing temperature rise is minimized, as shown in the graph of FIG. Also increases the bearing temperature, that is, the input increases.

Problems to be Solved by the Invention The oil-air lubrication of a constant supply oil amount described in the prior art is not a problem when the number of revolutions is constant, but when the number of revolutions is variable, it occurs due to the rotation of the bearing on the high speed side. It is better to change the supply amount according to the change in the number of revolutions, because the phenomenon that the invasion of the lubricating oil is hindered due to the influence of the wind pressure. This is also apparent from the experimental graph showing the loss (input at no load) with respect to the spindle speed in Fig. 2 when changing to two kinds of supply amount, which is 11000r.p.
At the low speed side, the amount of 0.15 cc / hr / Brg supplied was closer to the optimum oil amount, and at the high speed side, the result was that the supply amount of 0.225 cc / hr / Brg was closer to the optimum oil amount. ing. Therefore, there is a problem that ideal lubrication cannot be performed by the conventional oil-air lubrication method with a constant oil supply amount.

The present invention has been made in view of the above problems of the conventional technique, and an object of the present invention is to supply an appropriate amount of oil to a bearing together with an appropriate flow rate of air in accordance with the rotation speed. It is intended to provide a possible oil-air lubrication method.

Means for Solving the Problems In order to achieve the above object, the variable oil-air lubrication method according to the present invention is such that a timer cycle is changed at a cycle corresponding to a spindle rotation speed prestored in an NC device with rotation of a spindle. Then, the lubricating oil sent by operating the piston pump unit periodically by the pressure air sent intermittently in accordance with this timer cycle and the second air-oil mixing means and the second
In order to be sent to the air-oil mixing means, either the supply from the first air-oil mixing means side or the supply from the second air-oil mixing means side is selected according to the number of rotations of the spindle, and the timer period is set. The amount of lubricating oil and the flow rate of air are automatically changed synchronously and supplied to the main shaft bearing.

When the rotation speed changes, the NC command changes the timer cycle to switch the electromagnetic switching valve, select the fluid mixing means, mix the optimum amount of air with the optimum amount of lubricating oil, and supply it to the bearing.

Embodiment An embodiment will be described with reference to FIG.

Reference numeral 1 is a pneumatic drive piston pump unit, which is composed of a lubricating oil tank 2, a piston pump 3, a switching valve 4 and a check valve 5, and the pump 3 has an electromagnetic switching valve 8 interposed between pipes 6 and 7. , To the air source P. And conduit 6
A pressure gauge 9 and a pressure switch 11 for confirming the air pressure are provided in the middle of. The switching valve 4 in the pump unit 1 is of a type that is operated by the lubricating oil pressure discharged from the pump 3, and is connected to the pump 3 via a pipe line 12 and to the tank 2 via a return pipe line 13. The pipe 14 communicates with the electromagnetic switching valve 15. The voltage supplied to the solenoid SOL1 of the solenoid operated directional control valve 8 is supplied by the NC10 through the timer 16 whose ON / OFF cycle is automatically controlled according to the number of revolutions. Each time the timer 16 is turned ON, the piston pump 3
Is operated to intermittently supply the lubricating oil from the pipe line 14, and the operation of the pump 3 is confirmed by a pressure switch 17 provided in the middle of the pipe line 14. On the other hand, the electromagnetic switching valve 8 is connected to the air source P by a pipe line 19,
Conduit 21 to mixing valve unit 22 and again conduit
23 respectively communicate with the mixing valve unit 24. Instead of the mixing valve unit, a lubricating oil supply mechanism using an electrophoretic element nozzle can be used. Further, the electromagnetic switching valve 15 is connected to the mixing valve unit 22 by a pipe 25 and to the mixing valve unit 24 by a pipe 26, respectively. The mixing valve units 22 and 24 are provided with throttles 27 and 2 which communicate with the pipelines 21 and 23.
8 and oil reservoirs 29, 31 communicating with the pipes 25, 26, and check valves 32, 33 in series therewith.
Then, air and lubricating oil are mixed by the mixing nozzles 34 and 35 built in, and the air and the lubricating oil are communicated with the electromagnetic switching valve 38 via the pipelines 36 and 37, and one of the pipelines (36 or 37) is switched to the pipeline. It is connected to 39 and sends lubricating oil to the bearing together with air. The voltages applied to the solenoids SOL2 to SOL7 of the solenoid operated directional control valves 15, 18, 38 are switched in synchronism with the timer 16 under NC10 control, and the ON / OFF interval of the timer 16 depends on the rotation speed. At the same time, the discharge interval of the lubricating oil from the piston pump unit 1 changes, and at the same time, the electromagnetic switching valves 15, 18, 38 are switched at the same time, and the optimum flow rate of air is passed through one of the mixing valve units 22, 24. The optimum amount of lubricating oil mixed is fed to the bearing.

 Next, the operation of this embodiment will be described.

For example, it is assumed that the main shaft is now rotating at a rotation speed of 8000 rpm (low speed side). The NC 10 controls the timer 16 at a cycle corresponding to the spindle rotation that is input and stored in advance, and an appropriate amount of lubricating oil is delivered from the pump unit 1.
At the same time, the solenoids SOL3, SOL5, SOL7 are energized and the solenoid operated directional control valves 15, 18, 38 are switched to positions II, IV, VI respectively.
The mixing valve unit 24 side is communicated with the bearing, and the mixing valve unit 22 side is closed. As a result, the lubricating oil is mixed with the air adjusted to a flow rate corresponding to 8000 rpm by the throttle 28 and supplied to the bearing.
Next, when the rotation of the main shaft is switched to 13000 rpm, the cycle of the timer 16 is changed by NC, and the amount of lubricating oil delivered from the pump unit 1 per fixed time increases to an appropriate amount and at the same time the solenoids SOL2, SOL4, SOL6 Is energized, the solenoid operated directional control valves 15, 18, 38 are switched to the I, III and V positions respectively,
The mixing valve unit 24 side is closed, the mixing valve unit 22 side is connected to the main shaft, and the throttle 27
Lubricating oil mixed with air whose flow rate is adjusted to 13000 rpm is supplied to the bearing.

In order to simplify the circuit, as shown in FIGS. 5 and 6, either one of the electromagnetic switching valves 15, 18 or the electromagnetic switching valve 38 may be removed.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects.

An automatic variable oil amount circuit is provided, the amount of oil supplied is changed according to the number of revolutions, and at the same time, the mixing valve is switched by the switching circuit to mix the appropriate amount of lubricating oil with the appropriate amount of air. As a result, the bearing loss of the driving force is reduced and the temperature rise of the bearing is reduced, which reduces the thermal displacement.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a variable oil-air lubrication device showing an embodiment of a device for carrying out the method of the present invention, and FIG. 2 is an optimum supply amount of lubricating oil on the low speed side and the high speed side of the spindle speed. FIG. 3 is a graph showing that the temperature of the spindle bearing rotated at a constant speed changes with a change in the amount of lubricating oil.
FIG. 4 is a circuit diagram of a conventional constant oil amount type oil-air lubrication device, FIGS. 5 and 6 show another embodiment of the device for carrying out the method of the present invention, and FIG. From the figure Solenoid switching valve
FIG. 6 is a circuit diagram of a simplified variable oil-air lubrication device excluding 15, 18 and FIG. 6 is a circuit diagram of a simplified variable oil-air lubrication device excluding the electromagnetic switching valve 38 from FIG. 1 ... Pneumatic drive piston pump unit 3 ... Piston pump, 10 …… NC 16 …… Timer 22,24 …… Mixing valve unit 27,28 …… Throttle 8,15,18,38 …… Solenoid switching valve

Claims (1)

(57) [Claims] 1. A timer cycle is changed at a cycle corresponding to a spindle rotation speed stored in advance in an NC device according to the rotation of a spindle, and the piston pump unit is periodically cycled by pressure air sent intermittently according to this timer cycle. The lubricating oil sent to the first air-oil mixing means and the second air-oil mixing means can be sent to the first air-oil mixing means and the second air-oil mixing means depending on the rotation speed of the main shaft. A variable oil-air lubrication method, characterized in that either the supply from the mixing means side is selected, and the lubricating oil amount and the air flow rate are automatically changed in synchronism with the timer period and supplied to the main shaft bearing.