JP2569333B2 - Grinding spindle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a machine tool, and more particularly, to a grinding spinle that can be attached to a machining center.

2. Description of the Related Art For example, in a machining center, a rotary cutter such as a milling cutter, a milling cutter, a drill, or the like is mounted on a main shaft of a machine to perform cutting with the cutter. Most of the processing on the workpiece is performed mainly by high-speed processing by cutting. Therefore, just fixing the workpiece on the table can perform almost all required processing preset by a program. However, in order to further improve the processing accuracy and save labor, it is desirable that not only cutting with a blade but also grinding and polishing can be incorporated into the program and used together.

When considering grinding or polishing by a machining center, for example, when grinding and finishing a groove such as a cylindrical cam, the rotation speed of the main spindle needs to be very high.For example, when using a porazon grinding wheel, the cutting speed is 20
If it is 00m / min, if the diameter of the whetstone is 20mm, about 3
2000 rpm rotation is required.

When rotating the grindstone, that is, the grinding tool at such a high speed, it is conceivable to use a high-speed type machining center for spindle rotation. When cutting is desired, there is a problem that the bearing of the main shaft is weak and cannot be used.

There is also a method of using an attachment equipped with a mechanical speed increasing device such as a gear and a belt.In this case, however, the mechanical speed increasing device has a limit.
At about 000 rpm, there is a problem that the rotation speed does not increase any more.

Furthermore, there is a method of using an attachment equipped with an electric speed-up device such as a high-frequency motor, but in this case, the tool cannot be changed by the machining center because the device is expensive and electric wiring is required. There's a problem.

To solve the above problems, a machining center incorporating an air grinder using compressed air is disclosed in Japanese Patent Application Laid-Open No. 60-48257. This means that when the air grinder is mounted on the machining center, the air supply port to the grinder is attached so as to be connected by a joint with the air supply port provided in advance on the machine side,
The configuration is such that driving air is supplied to the grinder from outside the tool mounting spindle support boss of the machine. Such a configuration makes it possible to attach and use an air grinder as a grinding or polishing tool to a machining center without complicating the structure of the present machine and enabling exchange with another tool.

Objective In the configuration disclosed in Japanese Patent Application Laid-Open No. 60-48257, when the load on the grinder is increased, the table feed speed of the machine is selected and controlled in multiple stages, so that the load can be made constant. It is to try. However, when cutting is started, the load increases and the number of revolutions of the grinder is generally decreased. If the feed of the table is changed in accordance with the degree of the load, the feed is stopped in the worst case. Even if it does not stop, it is inevitable that the working speed will be significantly reduced. The decrease in the working speed cannot sufficiently fulfill the purpose of the machining center, such as improving the productivity of machining and saving labor in the factory such as unmanned operation.

In view of the above, an object of the present invention is to provide a grinding spindle capable of freely performing grinding or polishing at a desired high-speed rotation when the grinding spindle is mounted on a machining center to perform grinding or polishing.

The object of the present invention is to provide a holder that is removably attached to a machining center main shaft, a casing that is fixed to the holder, an air motor that is fixed in the casing, and that is rotatably supported by bearings in the casing. An output shaft of the air motor, wherein the output shaft is formed so that a grinding tool can be attached thereto, and a proportional valve controller is controlled in accordance with a detection value of a flow meter for detecting an air flow rate flowing through the air motor; This was achieved by a grinding spindle, characterized in that the flow rate to the feed was kept constant.

The configuration and operation of the present invention will be described in detail based on an embodiment shown in the drawings.

1 to 4, a grinding spindle 1 includes a casing 2 and an air motor 3 fixed in the casing 2.
And a holding member 4 for holding the air motor 3 in the casing 2 in a sealed manner, and a holder 6 fixed to the holding member 4 by bolts 5. The holding member 4 is fixed to the casing 2 by bolts 7.

The air motor 3 has an air motor casing 15 (for example, ceramic, FIG. 4) fixed to the casing 2 and a rotor 16 rotatably supported by the air motor casing 15, and the output shaft 8 is fixed to the rotor 16. The output shaft includes a bearing 9 mounted on the casing 2 and a holding member 4.
The bearing 10 is rotatably supported by the bearing 10 mounted thereon. For example, a ceramic vane 17 is slidably attached to the rotor 16.

The holder 6 can be detachably attached to a machine tool, for example, a spindle 11 of a machining center. The holder 6 has a tapered surface portion 12 so that it can be accurately positioned and adhered to the main shaft 11 of the machine tool, and is formed in the same manner as the tool holder or the holder of the work mounting pallet proposed earlier by the applicant himself. You.

The output shaft 8 of the air motor 3 is formed in the same manner as a spindle shaft on which a tool of a machine tool is mounted, to which a grinding tool 13 or another tool can be fixed.

A channel 14 for compressed air for driving the rotor of the air motor 3 is formed in the holding member 4, and the channel 14 is compressed via a channel 19 provided in the coupler 18. Connected to the source.

The casing 2 and the holding member 4 are formed with lubricating paths 20 and 21 for supplying lubricating oil to the bearings 9 and 10, and the lubricating paths 20 and 21 are intermediate paths formed in the air motor casing 15.
Connected by 22. The lubrication path 21 of the holding member 4 is connected to a lubricating oil source via a flow path 23 formed in the coupler 18. A mixture of oil and air can be used as the lubricating oil.

Lubricating oil that overflows after lubrication of the bearings is returned to the tank through return channels 24 and 25. The lubricating oil partially flowing from the tip of the casing 2 can be used for cooling the grindstone 13 along the output shaft 8.

When the above-mentioned grinding spindle is used, the main shaft 11 of the machine tool (machining center) does not rotate, but supplies compressed air from the flow path 23 to rotate the roller 16 of the air motor 3 at high speed. The air after rotating the rotor 16 passes through the air 26 formed in the air motor casing 16 and is discharged from the discharge path 27. The output shaft 8 is rotated at a desired high speed by driving the air motor 3, and the grinding tool 13 performs a desired grinding process.

By removing the grinding spindle 1 and attaching a normal tool to the spindle 11 and driving the spindle 11, low-speed machining can be performed as desired.

The operation of the grinding spindle 1 is performed, for example, by a control circuit shown in FIG.

The flow rate supplied to the air motor 3 in accordance with the rotation speed of the output shaft and the input voltage of the proportional valve controller corresponding to the flow rate are set in the controller in advance. Since the rotation speed of the output shaft at no load and the flow rate of the air motor 3 are proportional, if one relationship between the rotation speed and the flow rate is set, the other rotation speeds can be calculated.

A rotation speed instruction signal is input to a controller from a machine tool, for example, an NC device of a machining center.

When driving is started from the controller, a signal is sent to the solenoid valve, and the solenoid valve is turned on to open the pneumatic circuit.

Further, the controller outputs to the proportional valve controller a voltage corresponding to the rotation speed determined according to the rotation speed instruction signal from the NC device.

The opening of the proportional valve as a flow control valve is adjusted by an electric signal from the proportional valve controller, the flow rate of compressed air supplied from a compressed air source via a solenoid valve is adjusted, and the adjusted amount of air is supplied to the air motor. Supplied. At this time, the amount of air supplied to the air motor is constantly detected by the flow meter, and data is fed back to the controller by an electric signal.

The data from the flow meter and the flow rate stored in the controller are compared and operated, and the proportional valve controller is controlled according to the difference, and the proportional valve is adjusted so that the flow rate supplied to the air motor corresponds to the indicated rotational speed. By keeping the flow rate constant, the rotation speed of the air motor is kept constant.

If the rotation of the air motor decreases due to an increase in load during grinding or other reasons, the air flow flowing to the air motor decreases.The flow rate is detected by the flow meter, and the controller controls the proportional valve to increase the air flow. To

Further, when the air motor stops due to an increase in load, the pressure of the air circuit increases. In order to solve the problem due to this overload, a pressure switch is connected to the air flow path, a detection signal of the pressure switch is sent to the controller, and when the pressure of the air flow path is increased beyond a predetermined pressure, an emergency stop of the operation is performed. Let

Advantageous Effects According to the present invention, the grinding spindle has a holder having the same shape as the tool, and can easily be exchanged with the tool in the machining center. In the machining center, a coupler for supplying compressed air only needs to be additionally installed at the connection part, and the existing equipment can be used without requiring a special complicated structure.

Since the grinding spindle according to the present invention is provided with the air motor, high-speed rotation can be obtained independently of the main shaft rotation of the machining center. In addition, by providing a proportional valve in the air circuit of the air motor and controlling it by the controller, fluctuations in the number of revolutions due to fluctuations in the load can be eliminated, and the cutting speed can be integrated.

[Brief description of the drawings]

FIG. 1 is a top sectional view of a grinding spindle according to the present invention, which is a sectional view taken along line II of FIG. 2, and FIG. 2 is a sectional view taken along line II- of FIG.
FIG. 3 is a sectional view taken along line III-III in FIG. 2, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is an air control circuit diagram of the air motor. . 1 ... grinding spindle, 2 ... casing 3 ... air motor, 6 ... holder 8 ... output shaft, 11 ... spindle

Claims (1)

(57) [Claims] 1. A holder detachably attached to a machining center spindle, a casing fixed to the holder, and an air motor fixed in the casing.
An output shaft of the air motor rotatably supported by a bearing on the casing, the output shaft being formed so that a grinding tool can be attached thereto, and a detection value of a flow meter for detecting an air flow rate flowing through the air motor. Wherein the proportional valve controller is controlled in accordance with the rotation speed of the grinding spindle to maintain a constant flow rate to the air motor.