RU2819937C1 - Thread cutting method - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building and can be used in thread cutting devices. Method of thread cutting includes supply of shaft with cutting tool to part hole by screw movement, creation of pulling force, thread cutting by self-tightening of tool and withdrawal of the latter from hole. Screw movement of the shaft is created by at least one worm gear, in which the worm is made on the shaft, and the worm wheel is decelerated. Worm wheel is decelerated by means of a spring pressure retainer. Cutting tool feed and retraction is performed by means of worm wheel rotation. Worm wheel is also rotated by a stepper motor. Worm wheel is decelerated also by means of electromagnet. Cutting tool feed and retraction is performed also by another worm gear.

EFFECT: simplified design of the device, expanded its operating performances.

6 cl, 4 dwg

Description

The invention relates to mechanical engineering and can be used in thread cutting devices, including automatic machines.

The prototype is a method of thread cutting, including applying a pulling force and torque to the tool shank, performing self-tightening processing and periodically stopping the rotation of the tool to remove chips [Pat. RF 2638138, IPC B232G 5/06, 2017].

The disadvantages of the prototype are:

- the complexity of the device that implements the method, and the design complexity of the operation of this device in automatic mode;

- the difficulty of determining the moment at which it is necessary to remove the force from the cutting tool in order to ensure self-tightening processing;

- in addition, the specified device requires readjustment when changing the pitch of the thread being cut.

The objective of the invention is to simplify the design of the device that implements the method, expand functionality and improve performance characteristics.

The problem is solved by the fact that in the thread cutting method, which includes feeding a shaft with a cutting tool by a screw movement to the hole of a part, creating a pulling force, cutting a thread by self-tightening the tool and removing the latter from the hole, the screw movement of the shaft is created by at least one worm gear, in which the worm is placed on the shaft, and the worm wheel is braked.

The worm wheel is braked using a spring-loaded clamp. The supply and removal of the cutting tool is carried out by rotating the worm wheel. The worm wheel is also rotated by a stepper motor. The worm wheel is also braked using an electromagnet. The supply and removal of the cutting tool is also carried out by another worm gear.

These distinctive features allow you to achieve the following advantages compared to the prototype.

Creating a helical movement of the shaft by at least one worm gear, in which the worm is mounted on the shaft and the worm wheel is braked, makes it possible to simplify the design of the device implementing the method. In addition, it becomes possible to automatically remove the axial (pressure) force on the cutting tool during self-grabbing (when a pulling force appears), which expands the functionality and also improves performance characteristics.

Braking the worm wheel by means of a spring pressure latch simplifies the design of the device implementing the method, since such a latch is a simple part and practically does not complicate the design as a whole.

The supply and removal of the cutting tool by rotating the worm wheel also simplifies the design of the device implementing the method, since it does not add practically any additional parts to the device.

The rotation of the worm wheel and the stepper motor increases ease of use and allows you to automate the process of approaching and retracting the cutting tool by supplying control pulses to the stepper motor. This all improves performance.

Braking the worm wheel by means of an electromagnet improves the quality of cutting small threads, and also simplifies the automation of the device, which improves performance characteristics.

The supply and retraction of the cutting tool through another worm gear expands the functionality and improves performance characteristics, since it is possible to reduce the time for the preparatory operation and increase labor productivity.

The invention is illustrated by drawings.

In fig. 1 shows a thread cutting device with a spring pressure lock. In fig. Figure 2 shows a device with an electromagnet. In fig. Figure 3 shows a device with two worm gears. In fig. 4 shows a version of a simplified worm gear.

The device for cutting threads contains a shaft 1 connected to the drive, one part of which is made in the form of a worm 2, mated to a worm wheel 3, which has the ability to interact with a spring pressure latch 5 fixed on the base 4 and rigidly fixed to an axis 6, mounted with the possibility of rotation in some supports of the base, in the other supports of which a shaft is placed with the possibility of rotation and longitudinal movement, at the end of which a chuck 7 with a cutting tool (for example, a tap) 8 is fixed. Instead of a latch 5, an electromagnet 9 can be used to brake the worm wheel, which can interact with the worm wheel wheel. A second worm 10 can be made on the shaft, having a helix pitch different from worm 2 and coupled with a second worm wheel 11, which has the ability to interact with the second electromagnet 12. The worm can be made in the form of a shaft 13, on which it is fixed and covers it has at least one coiled spring 14, capable of engaging with the wheel 15.

The method is implemented as follows.

To cut a thread in the hole of a part (not shown), a motor (not shown) is turned on, rotating shaft 1 through a spline connection. Since the worm wheel 3 is kept from rotating by a spring pressure clamp 5, the worm 2 together with shaft 1, chuck 7 and tap 8 will while rotating, move along its axis, i.e., perform a screw movement (Fig. 1).

When it comes into contact with the part, the tap, due to the axial force of the worm and the torque of the engine, begins to cut into the hole. After the tap self-locks, a pulling force will begin to act on shaft 1, which occurs when the tap is deepened into the hole.

If the thread pitch and the worm helix pitch are the same, then the worm wheel will still be stationary.

If the thread pitch of the tap is greater than the pitch of the helix of the worm, then due to the pulling force the axial movement of the worm will increase, the worm wheel 3 will begin to rotate (in this case counterclockwise), overcoming the force of the spring pressure clamp 5 and without interfering with the axial movement of the tap, determined by the pitch of the thread being cut. in the thread hole, as a result of which the quality of the latter will be determined directly almost only by the parameters of the cutting tool.

If the thread pitch of the tap is less than the pitch of the helix of the worm, then the axial movement of the worm 2 will decrease, and the worm wheel 3 will rotate clockwise, also overcoming the force of the spring pressure clamp 5 and without interfering with the axial movement of the tap.

After threading is completed, the engine rotation is reversed, as a result the tap will turn out and come out of the hole.

If, when bringing the tap to the part, it turns out, for example, that there is no hole in it, then the tap will rest against the part, and the worm wheel 3 will rotate, overcoming the force of the spring pressure clamp 5, which will prevent breakage of the cutting tool.

Thus, it is possible to cut threads with a pitch different from the pitch of the helix of the worm, without rebuilding the device each time to the size of the thread pitch. Moreover, if the pitch of the thread and the helical line of the worm are the same, then when a pulling force occurs, the axial force acting on the worm before it automatically ceases to act. With other pitch ratios, in addition to the pulling force, the force generated by the interaction of the worm wheel with the spring pressure clamp will also be transferred to the tap, which, with a small pitch of the thread being cut, can deteriorate its quality. This drawback can be eliminated by braking the worm wheel with an electromagnet (Fig. 2).

The electromagnet 9 is turned on, as a result of which the worm wheel 3 (made in this case from a magnetic material) is attracted to it (to the core of the electromagnet) due to the elastic deformation of its material and/or the movement of the axis 6 within the limits of the axial play. As a result, the worm wheel is braked, and the subsequent activation of the electric motor will cause a screw movement of the shaft. After the pulling force has arisen, the electromagnet is turned off, and the worm wheel begins to rotate idle, without interfering with the work of the tap. You can determine the moment when the electromagnet turns off, for example, by installing it on an elastic support, i.e., making a non-rigid (elastic) mount. Then, with a larger pitch of the thread being cut, due to the rotation of the worm wheel, the electromagnet will deviate in one direction, and with a smaller pitch, in the other. These deviations, recorded by the corresponding sensor, can become control signals to turn off the electromagnet.

If necessary, quick approach (approach) of the tap to and from the part can be done by connecting the worm wheel to the shaft of a stepper motor (not shown). Then, after unscrewing the tap from the hole, the stepper motor is turned on, as a result of which the worm wheel begins to rotate, quickly moving shaft 1 and moving the tap away from the part. In this case, during the thread cutting process, if the worm wheel rotates, the stepper motor shaft will rotate together with it, without interfering with the specified process. Moreover, since a certain force is required to rotate the stepper motor shaft by an external force, in certain cases it can be used to brake the worm wheel, and there will be no need for a latch.

To quickly move the tap to and from the part, a second worm gear can be used instead of a stepper motor (Fig. 3). After unscrewing the tap from the hole, the electromagnet 9 is turned off (if it was turned on), and the electromagnet 12 is turned on, as a result of which the worm wheel 11 is braked. If the pitch of worm 10 is greater than the pitch of worm 2, then at the same engine speed the axial movement of shaft 1 will increase, and the tap 8 will move away from the part faster.

The worms can be made in a simplified version in the form of a shaft 13 with a spring 14 and a wheel 15 pressed onto it, which will further simplify the design (Fig. 4). Note that since the thread cutting process is controlled only using electrical signals, this process is easy to automate.

The implementation of the invention will make it possible to create a simple, reliable and easy-to-use device for thread cutting, which, if necessary, can be used as the basis for a thread-cutting machine.

Claims (6)

1. A method of thread cutting, including feeding a shaft with a cutting tool by a screw movement to the hole of a part, creating a pulling force, cutting a thread by self-tightening the tool and removing the latter from the hole, characterized in that the screw movement of the shaft is created by at least one worm gear, in which the worm performed on the shaft, and the worm wheel is braked. 2. The method according to claim 1, characterized in that the worm wheel is braked by means of a spring pressure latch. 3. The method according to claim 1, characterized in that the supply and removal of the cutting tool is carried out by rotating a worm wheel. 4. Method according to any one of paragraphs. 1-3, characterized in that the rotation of the worm wheel is also carried out by a stepper motor. 5. The method according to claim 1, characterized in that the worm wheel is also braked by means of an electromagnet. 6. The method according to claim 1, characterized in that the supply and removal of the cutting tool is carried out by another worm gear.