JPS61103047A - Speed change mechanism - Google Patents

Abstract

PURPOSE:To simplify the structure and to facilitate operation by entraining an endless belt over a pair of multi-stage pulleys arranged in parallel then providing tensile means to respective belt while a belt support/guide around respective belt. CONSTITUTION:Multi-stage driven pulley 4 and a drive pulley 6 are arranged in parallel then endless belts 7a, 7b are entrained over said pulleys 4, 6 while a tension roller 8 is contacted against said belts 7a, 7b and belt support/guides 13, 14 are provided around respective belt 7a, 7b. Upon application of tension onto a belt at some stage, the remaining belt is loosened and supported through the belt support/guide. Consequently, it is not required to move the belt in axial direction of pulley but simply required to control the tensile means resulting in simplification of structure and facilitation of operation.

Description

[Detailed description of the invention] Field of application of invention The present invention relates to a transmission mechanism using a belt.

Prior Art and Problems to be Solved by the Invention Conventionally known transmission mechanisms using belts include those using cone pulleys and those using multistage pulleys. In these conventional transmission mechanisms, a belt is placed between two pulleys, and the rotation ratio is changed by shifting the belt in the axial direction of the pulleys. For this reason, with multi-stage pulleys, there are those that remove the tension pulley, loosen the belt, and use a lever to change the speed, and those that use a lever to shorten the pitch between the pulleys, loosen the belt, and then use the lever to hook the belt. There is something to change the speed. Such a conventional transmission mechanism has a complicated structure, and belt hooking and changing operations are troublesome and are mostly performed manually.

Means for Solving the Problems In the present invention, endless healds of the same number as the number of stages are applied between a pair of multi-stage pulleys, a tension applying means is provided for applying tension to each belt, and a predetermined shape is provided around each belt. belt support guides are arranged. Belts generally tend to curl into a circular shape when there is no tension, and if there is a guide of a predetermined shape around the belt, the belt will take on the shape of the guide. If there is a clearance between the belt and the pulley when the belt is in this shape, the belt will be separated from the pulley and supported by the guides around it.

Based on this principle, the transmission mechanism according to the present invention has, in addition to the above-mentioned configuration, when tension is applied to a belt in a certain stage, the tension in the remaining belts is relaxed, Transmission is carried out through the stages, and the tensioned belts are supported by respective belt support guides.

Example The present invention will be explained in more detail below with reference to the drawings.

1 to 3 show a speed change mechanism of a spindle device of a machine tool, and in FIG. 3, 1 is a tool spindle and 2 is a spindle motor. A driven boob I74 is attached to the tool main shaft 1 within the transmission mechanism nozzle 3, and a drive pulley 6 is attached to the output shaft of the motor 2 or a shaft 5 extending from the output shaft. The driven pulley 4 and the drive boob IJ 6 are arranged parallel to each other.

In the embodiment shown in the figure, both booles IJ4, 6 are formed as two-stage pulleys, and in FIG. 3, the large pulley 4a of the driven pulley 4 and the small pulley 6a of the driving pulley 6 are associated to form a low speed stage, The small boob IJ 4 b of the driven pulley 4 and the large pulley 6 b of the driving pulley 6 are associated to form a high speed stage.

Two endless bells 7a and 7b corresponding to the number of stages are hung on the pulleys of each stage. Each belt 7
The lengths of a and 7b are longer than the shortest running circumference between the associated pulleys when no tension is applied. A tension roller can be engaged with each of these belts 7a, 7b, but in the embodiment, the tension roller 8 is common, and the tension roller 8 is connected to all stages of each pulley 4, 6. It is located between the running parts of both bells 7a and 7b and can move between two positions, and when it is in one position shown in FIG. When the heald 7b is in the other position shown in FIG. 2, tension is applied from the outer side of the belt and tension is applied to the other belt 7a. is no longer granted. The tension roller 8 is rotatably attached to one end of an arm 9, and the arm 9 is rotatably supported on a fulcrum shaft 10 at its intermediate portion, and at the other end is connected to an operating rod of an actuator 11 consisting of a hydraulic cylinder. 12. Therefore, actuator 11
The tension roller 8 can be moved between two positions by controlling the hydraulic pressure.

It is clear that when tension is applied to each belt 7a, 7b, the associated pulleys are connected, and in FIG. 1, belt 7a connects pulley 4a and pulley 6a to form a low speed system. Bell) 7b in Figure 2
connects the pulley 4b and the boolean IJ5b to form a high-speed system. Belt 7b in FIG. 1 and belt t-7a in FIG. 2 are suspended from their respective associated pulleys 4b and 6b, 6a and 6b. Referring to FIGS. 1 and 3, a belt support guide 13 having a predetermined shape is arranged around the belt 7b. The heald support guide 13 has an elliptical support surface along almost the entire circumference of the bell 7b, but it is partially discontinuous because the tension roller 8 passes therethrough.

Further, around the bell) 7a, a hook-shaped first belt support guide 14 corresponding to the semi-outer circumferential surface of the small diameter pulley 6a and a second belt supporting guide 15 corresponding to the semi-outer circumferential surface of the large pulley 4a are provided.
is formed, and the second support guide 15 is formed by a part of the housing 3.

Also in this case, the first and second belt support guides 14.
15 does not necessarily cover the entire outer periphery of the bell l-7a, but includes one continuous part. Therefore, in the present invention, the term "around the belt" does not necessarily mean the entire circumference of the belt. The predetermined shape of the belt support guide varies depending on the size of the related pulleys, and is difficult to define, but it covers the substantial semicircle of the opposing outside of the related pulleys, and covers the outer circumference of the boob. It is desirable to have a spacing of the belt thickness plus 2 to 3 fi between the surface and the inner surface of the support guide, with the belt loosened or untensioned; It has a shape suitable for being supported by a support guide in any state.

The reason why belts can be supported in this way is that modern belts have a tendency to curl into an almost circular shape when no tension is applied, and when the shape of the heald, which tends to curl, is controlled from the outside, it can easily be shaped into the desired shape. This exposes the idea that it can be maintained. As an example of such a belt, the cross-sectional shape of the belt is shown in FIG.
A belt composed of a linear canvas 71, a chloroprene rubber layer 73 having six polyester cords 72, and a bottom rubber 74 made of fiber-filled chloroprene rubber can be used. Furthermore, a belt with grooves such as ■ belt can also be used. Furthermore, belt support guides 13, 14.1
As shown in FIG. 3, the belt 5 may have a side edge 13a protruding inwardly from the support surface in order to restrict displacement of the belt in the pulley axis direction, or it may be formed in the shape of a groove to accommodate the belt. You can also

As described in detail, according to the present invention, there is no need to move the belt in the axial direction of the pulley, and it is only necessary to simply control the means for applying tension to the heald, thereby providing a transmission mechanism that is simple in structure and easy to operate. It will be done.

Furthermore, by using two stages of pulleys, applying tension to the two belts with a common tension pulley, and controlling the position of the tension pulley with an actuator, switching between high and low speeds can be easily and reliably controlled under automatic control. It can be carried out.

[Brief explanation of the drawing]

1 is a sectional view of the transmission mechanism according to the present invention taken along the line II in FIG. 3; FIG. 2 is a view in another state from FIG. 1;
FIG. 3 is a longitudinal sectional view of FIG. 1, and FIG. 4 is a diagram showing an example of the cross-sectional shape of the belt. 4... Driven pulley, 6... Drive pulley, 7a,
7b... Belt, 8... Tension roller, 11... Actuator, 13, 14.15... Heald support guide. Figure 1

Claims (1)

[Scope of Claims] 1. A pair of multi-stage pulleys with mutually related stages are arranged in parallel, and endless belts with the same number of stages as the number of stages are hung between the pair of multi-stage pulleys, and tension is applied to each belt. A belt support guide of a predetermined shape is arranged around each belt, and when tension is applied to a certain stage of belts, the tension of the remaining belts is loosened, and the tension of the belts to which tension has been applied is loosened. A transmission mechanism in which power is transmitted through stages, and the tensioned belt is supported by each belt support guide. 2. The multi-stage pulley is a two-stage pulley, and a belt is hung on each stage, and the belt tension applying means connects the tension pulley with a tension pulley disposed between the running parts of the two belts. an actuator for moving between two positions, and when the tension pulley is in one position, it applies tension to one belt and loosens the tension of the other belt;
2. The transmission mechanism according to claim 1, wherein a reverse tension is applied when the transmission mechanism is in the other position. 3. The transmission mechanism according to claim 2, wherein one pulley is connected to a motor and the other pulley is connected to a tool main shaft of a machine tool.