JP3158882U - Deep hole grooving machine using air turbine - Google Patents

Abstract

Disclosed is a cutting tool that is capable of machining a groove of an arbitrary shape with high accuracy in pipe machining with a small inner diameter and depth.
A cutting apparatus is equipped with a high-speed air turbine head 1 and has a cutter that can be attached and detached with one touch at the tip. The entire head is supported by a long pipe 3 and incorporates a tube for supplying air to the air turbine and a tube for supplying cutting fluid. The pipe can be rotatably fixed, and a turbine rotation sensor 6 and a vibrating body 7 can be inserted in the middle of the pipe. Deep hole machining, which was impossible before, can be realized.
[Selection] Figure 1

Description

  The present invention relates to a mechanism for a machining head for cutting that processes the inside of a deep hole with a small diameter.

  In processing parts of optical instruments such as a microscope, a telescope, and a camera, various grooving and finishing processes are important for the inner diameter of a relatively small cylindrical part. These are often unsuitable for mass production techniques such as injection molding and die casting, and most rely on dedicated machining as post-processing. Existing machine tools, such as gun drilling, are sufficient if simply drilling deep holes, but in the case of precisely carving cam grooves for camera zoom lens guides, for example, a computer controlled lathe or milling machine or Processing by these combinations is necessary.

  However, with these methods, it is generally difficult to machine deep internal diameters, and it is necessary to develop a dedicated machine. However, there is a limit to machining heads with very long shank lengths, so that the groove shape can be freely adjusted with high precision. There was a limit to processing. This is because a long distance from the support portion of the processing head to the processing portion at the tip makes it impossible to secure sufficient rigidity, causing vibration due to the cantilever mode during processing and causing a problem.

  As a means to overcome these disadvantages, recently, a processing machine has been proposed that increases the accuracy by reducing the cutting resistance by rotating the tool at a high speed. Although it is the mainstream, it is necessary to make the head itself extremely small, especially in the case of deep hole drilling with a small diameter, and there is a limit when it is necessary to change the rotation direction. The diameter of the cutter is inevitably reduced, and the rotational speed of the motor or the like must be increased considerably in order to make the processing speed appropriate.

JP 2003-135486 JP

Nakanishi Co., Ltd. s-Max Handpiece Catalog

  The problem to be solved is to realize high-speed rotation while suppressing vibration as much as possible under the adverse condition that the machining head is sufficiently small in the machining of a small-diameter deep hole and the support part of the machining head is considerably elongated.

  The present invention adopts a compact air turbine system in that the cutter can be rotated at an ultra-high speed and generates less vibration, and its configuration is simplified, so that it can be applied to conventional machine tools. High-pressure air of about 0.2 Mpa that can be easily procured in a normal factory was used as a medium for facilitating attachment / detachment and unitization, and for cooling the turbine drive and processing heat. Basically, it is a highly reliable head with very few failures because no electrical parts are mounted on the machining head. The turbine head is supported by a small-diameter metal pipe, and the base of the pipe is fixed to a bracket for attaching to the processing machine body. This bracket also serves as a manifold of high-pressure air supplied to the turbine and an air tube for cutting fluid and air cooling. It is also possible to insert a piezoelectric sensor for detecting the rotational speed by sound and an ultrasonic vibrator that is effective in reducing cutting resistance and discharging cutting powder in the middle of the support pipe.

  Since the vibration of the tool itself is suppressed to an extremely low level by ultra-high speed and ultra-light load cutting using an air turbine, there is almost no need to increase the rigidity of the support portion of the machining head. As a result, it has become possible to realize deep hole machining, which has been considered impossible until now. Specifically, even in metal processing where the inner diameter is around 20 mm and the depth exceeds 500 mm, this turbine head allows free grooving and finishing by computer control. In higher-accuracy machining, the rotational speed can be changed and stabilized by speed control, and improvement of the finished surface can be expected with the aid of ultrasonic vibration. Also, the direction of the turbine head can be changed by rotating the pipe, and the turbine head can be fixed in an easy positional relationship depending on the work contents.

It is a general view of the air turbine type deep hole processing machine proposed in the present invention. It is a control circuit diagram of the fluid supplied to a turbine. It is a cross-sectional detail drawing of a turbine head and a support pipe. It is a mounting diagram of a speed sensor and a vibrating body.

  A small cylindrical turbine head is fixed to the support pipe at a right angle, and the rotation axis of the tool can be opposed to the inner wall of the workpiece at a right angle. The support pipe is fixed to a bracket that also serves as an intake / exhaust manifold. High pressure air and cutting fluid ports are provided. The bracket is fixed to the tool mounting base of the machine tool main body with bolts or the like, and the coordinates of the tool tip can be aligned with a positioning jig or the like with a certain offset from the reference position of the tool base. In addition, a terminal block for supplying electrical signals for a speed sensor and an ultrasonic vibration head can be mounted on the bracket.

  FIG. 1 is an oblique perspective view of an exemplary embodiment of the device of the present invention, showing the arrangement of the main components. The turbine head 1 is arranged at the front end of the support vip 3 so that the rotation axis of the processing cutter 2 is orthogonal to the axis of the support pipe 3. In FIG. 1, the cutter is attached upward, but the pipe 3 can be rotatably fixed to 4, so that it can be fixed according to cutting conditions such as downward and lateral, for example. The air tubes passing through the inside of the pipe 3 are twisted by the rotation, but there is no problem because the rotation angle range is fixed.

  It is also possible to arrange the piezoelectric sensor 6 and the ultrasonic vibrator 7 in the middle of the pipe. There are various methods for detecting the rotational speed of the turbine, but it is generally difficult to effectively arrange the turbine in a narrow space. In the present invention, a piezoelectric ceramic is used as a sensor. This is based on the principle that an acoustic signal, which is the fundamental frequency, is regarded as vibration because the maximum rotational speed of the turbine reaches 7000 rpm. This turbine sound is of a level that can be heard well by human ears during driving, and is suitable for use as a sensor. Also, since the turbine head itself is extremely quiet, using this fundamental frequency is optimal for subsequent signal processing. The wiring of the electrode can be passed through the inside of the support pipe 3, which is advantageous from the viewpoint of electromagnetic noise, but may be provided on the outer surface of the pipe. The same applies to the ultrasonic transducer 7. Although the usefulness by adding ultrasonic vibration is already well known, it is very effective to use it in a ring shape as in the present invention, and the driving frequency is matched with the natural vibration in the axial direction of the pipe 3. It is common. Since both the sensor 7 and the vibrator 8 are made of ceramics having stable strength and dimensional accuracy, it is not a problem in the case of a lightly loaded turbine head to be laminated on the middle part of the pipe.

  FIG. 2 is a control circuit diagram of the fluid supplied to the turbine head. Here, four connector ports are mounted on the manifold, which are used for high-pressure turbine air, cutting fluid, air-cooled air, and exhaust, but are not limited to the arrangement or type of medium. The purpose of pressure control of turbine high-pressure air is to place a commercially available electro-pneumatic regulator and process the signal from the speed sensor 6 to control the turbine rotational speed to be constant, or simply control the cutting force by keeping the pressure constant. Also used for.

  FIG. 3 shows the inside of the turbine head and the support pipe as a schematic sectional view. The internal structure of the turbine head 1 is very simple, and includes a turbine blade 11 integrated with a rotating shaft, a ceramic ball bearing 12 that rotatably supports the blade, and a case for housing them. Since the turbine blade is a consumable that is periodically replaced, the screw-in cap 13 is removed and the bearing and the blade are replaced at a time. Since it is basically an ultra-high speed rotation of 400,000 rpm, it is necessary to exchange the dynamic balance accurately in assembly units. The high-pressure air is supplied from the nozzle 1 a, rotated around the turbine blade 11, exhausted from the opening 1 b, and discharged from the manifold to the atmosphere through the gap of the support pipe 3.

  The workpiece being processed is blown with cooling air from the nozzle 1c in order to prevent temperature rise. At the same time, cutting fluid can be sprayed, but because of the ultra-high speed rotation, a high-speed flow of air is generated around the tool 2 and the liquid cannot easily come into contact with the workpiece. For this reason, it is common to spray the cutting fluid in the form of a mist with cooling air to simultaneously provide a cooling effect and a lubricating effect. Although not shown in detail in FIG. 3, it is possible to spray by the principle of spraying by additionally providing a nozzle 1d. The nozzle portion is connected to a thin metal pipe 31 or plastic tubes 32 and 33 and guided through the support pipe 3 to reach the manifold bracket 4. The connecting part between the support pipe and the manifold is fixed by a small collar 34, but the pipe can be rotated at a certain angle inside the collar, and it can be turned by plus or minus 180 degrees by holding the pipe by hand and twisting it. Is possible. As a result, the orientation of the cutter 2 can be freely changed, so that the cutter 2 can be set at the most efficient angle while being attached to the tool table. After the adjustment, it is fixed by a set screw 35 omitted in the drawing.

  FIG. 4 shows the configuration of a speed sensor and an ultrasonic transducer that enable high-precision processing. As described above, the turbine head is extremely quiet and generates almost no vibration other than the rotation sound of the turbine, and the cutting sound has only components of the fundamental wave and the harmonics synchronized with the rotation speed f1 of about 7 kHz. Therefore, the sensor 6 is optimally an annular piezoelectric element that effectively converts this component into a voltage. The generated voltage is subjected to appropriate FV (frequency-voltage) conversion through the sensor amplifier 63, and input to the electropneumatic regulator shown in FIG. Separately, reference numeral 7 in FIG. 4 denotes a piezoelectric element for ultrasonic vibration, which is applied with ultrasonic vibration in the pipe axis direction by the alternating current power source 72 for vibration, and finally the tip of the cutter 2 vibrates. It reduces cutting resistance and facilitates discharge of cutting powder. In FIG. 4, the sensor 6 and the vibrator 7 are assembled in series via the insulator 62, but it is of course possible to use the sensor alone or the vibrator alone regardless of this configuration.

  By mounting the air turbine on an elongated pipe-shaped support and installing it on the tool table of a machine tool via a bracket that also serves as a manifold, it is possible to easily achieve deep inner diameter machining that has been impossible until now. I was able to do it.

DESCRIPTION OF SYMBOLS 1 Turbine head 2 Cutter 3 Support pipe 4 Manifold Pipe support bracket 5 Tool mount bracket 6 Piezoelectric sensor 7 Ultrasonic vibrator 11 Turbine blade 12 Ball bearing 13 Cap 31 Turbine drive high pressure air pipe 32 Cooling air tube 33 Cutting fluid tube 34 Support Pipe fixing collar 35 Set screw 61 Electrode lead wire 62 Insulating ring 63 Sensor amplifier 71 Common lead wire 72 AC power source for vibration

Claims (4)

  An air turbine mechanism is installed at the tip, and it has a long hollow shaft part that accommodates the pipe for supplying air and cutting oil and is connected to the machining head mounting part to hold the air turbine mechanism at an angle. A cutting head having a detachable bracket for attaching to a general-purpose machine tool at the head attaching portion and a manifold between connector portions for supplying air and cutting oil.   The electropneumatic regulator for making the cutting force and the cutter rotational speed constant or variable by changing the turbine supply air pressure constant or by changing the command value is mounted in the air supply system. Cutting head.   The cutting head according to claim 2, wherein a ring-shaped piezoelectric element that detects the number of rotations based on a frequency of rotation sound is laminated on a part of the turbine support pipe.   2. The cutting head according to claim 1, wherein a ring-shaped piezoelectric element for reducing the cutting resistance by applying ultrasonic vibration in the central axis direction of the turbine support pipe is laminated inside the pipe.

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