JPH0765682B2 - Rotational speed transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention is arranged between a rotary drive source and a rotated body, and transmits the rotational force from the rotary drive source to the rotated body. At the same time, it relates to a rotation speed transmission capable of changing the rotation speed of a rotated body.

(Prior Art) Conventionally, a plurality of spur gears are combined between a drive gear and a driven gear as a device for changing the rotation speed of a driven body such as a device for changing the rotation speed of a spindle of a machine tool. There is used a device which intervenes an intermediate gear formed by moving the intermediate gear in the direction of the rotation axis to change the meshing ratio of each gear to change the rotational speed.

In a rotation speed transmission using such a gear train,
The intermediate gear is slidably mounted on a rotatably supported intermediate shaft by being guided by a slide key or the like, and a guide plate is provided in a groove provided around the outer periphery of the intermediate gear in a direction orthogonal to the rotating shaft. It is designed to be moved in the axial direction by inserting the guide plate from above and moving the guide plate forward and backward in the direction of the rotation axis with a hydraulic cylinder.

(Problems to be Solved by the Invention) In the above-described conventional rotational speed transmission, when the intermediate gear is rotating, the groove portion and the guide plate inserted into the groove portion do not make metal contact with each other, It is necessary to inject a large amount of lubricating oil into the gap between the groove and the guide plate. However, even then, heat generation in this gap is unavoidable,
Especially when rotating at high speed, there is a problem that thermal accuracy is adversely affected. In addition, a hydraulic cylinder for driving the guide plate has to be specially installed, which complicates the structure and complicates the assembling work.

The present invention has been made in consideration of such points,
It is an object of the present invention to provide a rotation speed transmission that generates a small amount of heat and can have a simple structure.

[Structure of Invention]

(Means for Solving the Problems) In the present invention, a drive gear, a driven gear, and an intermediate gear, each of which is formed by connecting a plurality of spur gears having different numbers of teeth, wherein the intermediate gear is the drive gear and the driven gear. A device for arranging gears at the same time so that they can mesh with each other, changing the meshing position of each gear by moving the intermediate gear in the direction of the rotation axis, and changing the rotational speed of the driven gear. Both ends are rotatably supported by idler shafts slidably inserted and held in two cylinders arranged opposite to each other, and pressure fluid is supplied to each cylinder via a direction switching valve. It is characterized in that the source is connected.

(Operation) According to the present invention, the pressure fluid is supplied to or discharged from each of the fixed cylinders via the directional control valve to axially move the idler shaft, so that the intermediate gear rotatably supported by the idler shaft is moved. It is possible to change the rotational speed by changing the meshing state of the driving gear and the driven gear.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

The figure is a cross-sectional view showing an example in which the rotation speed transmission according to the present invention is used as a rotation speed transmission for a spindle of a machine tool. In the figure, reference numeral 11 is a drive gear that gives a rotational drive force, and a large spur gear 11a and a small spur gear 11b having different numbers of teeth are used as a rotary shaft.
It is constructed by lining up along 12. The rotating shaft 12 is a bearing 13
Both ends are supported by a rotary drive source, for example, an electric motor 14
Are linked to.

Reference numeral 21 is a main shaft of the machine tool, and a driven gear 22 is fitted to the main shaft 21. The driven gear 22 is composed of a large spur gear 22a having a large number of teeth and a small spur gear 22b having a small number of teeth, which are continuously arranged in the spindle axis direction.

Between these drive gear 11 and driven gear 22, an intermediate gear
31 is disposed and the driving gear 11 and the driven gear 22 are simultaneously meshed with each other, so that the rotational driving force of the driving gear 11 is driven.
22 to be able to communicate. This intermediate gear 31
Three spur gears with different numbers of teeth, namely large spur gear 31
It is configured by connecting a medium spur gear 31b and a small spur gear 31c in series. The number of teeth and the axial arrangement position of these three spur gears are determined by the number of teeth and the arrangement position of the large and small spur gears of the driving gear 11 and the driven gear 22, which mesh with each other.

The driving gear 11, the driven gear 22 and the intermediate gear 31 are the main shaft 21
Are arranged in a spindle head 23 that is rotatably held, and cylinders 24 and 25 that open toward the spindle head inward direction are provided in the spindle head 23 at positions facing each other with an intermediate gear 31 in between. Has been. Inside the cylinders 24 and 25, the idler shaft 3
The two end portions 33, 34 of the second member are slidably inserted in the axial direction to form a hydraulic piston / cylinder mechanism. An intermediate gear 31 is rotatably supported by a bearing 35 at the center of the idler shaft 32.

A large diameter portion 34a and a small diameter portion 34b are formed at one end 34 of the idler shaft 32, and a small diameter cylinder chamber 25b is formed inside the cylinder 25. A float piston 35 that slides in the cylinder chamber 25b is loosely fitted in the small diameter portion 34b. The effective area of the float piston 36 is made larger than the effective areas of the end portion 33 and the large diameter portion 34a, and the cylinder 25 that slidably supports the large diameter portion 34a communicates with the cylinder chamber 25b in which the float piston 36 slides. A cylinder chamber 25c is provided in the portion to be operated.

Innermost part of cylinder 24 and cylinder chamber 25c of cylinder 25
Cylinder chamber 24a and cylinder chamber 25c are
An oil port 26 and an oil port 27 for supplying pressure oil are drilled, and these oil ports 26, 27 are connected to a pressure fluid supply source (not shown) via a direction switching valve 41. Also,
An oil port 28 for supplying pressure oil to the cylinder chamber 25b is bored in the innermost portion of the cylinder 25, and the oil port 28 is connected to a pressure fluid supply source (not shown) via a direction switching valve 42. There is.

Next, the operation of this embodiment having such a configuration will be described.

The drawing shows a medium speed rotation state, in which the small spur gear 11b of the drive gear 11 and the small spur gear 22b of the driven gear 22 are connected via the large spur gear 31a of the intermediate gear 31. In this case, the cylinder chamber 24a and the cylinder chamber 25b each have an oil port.
Pressure oil is supplied through 26 and 28, and cylinder chamber 25c
Is not supplied with pressure oil. For this reason the idler shaft 32
The end 33 is pushed to the right in the drawing and the float piston 36
Is pushed to the left in the drawing and has stopped at the step 25c.

To change from this state to low speed operation, the directional control valves 41, 4
2 is operated to discharge the pressure oil from the cylinder chambers 24a and 25b, and the pressure oil is supplied to the cylinder chamber 25c from the oil port 27. As a result, the float piston 36 first moves to the innermost end of the cylinder 25 (moves to the right in the drawing), and then the large-diameter portion 34a is pushed to the left in the drawing by the pressure oil, and the end 33 of the idler shaft 32 is pushed. Moves to the deepest end of the cylinder 24. Intermediate gear 31
Moves leftward in the drawing together with the idler shaft 32, and its large spur gear 31a meshes with the small spur gear 11b of the drive gear 11,
31c is in a state of meshing with the large spur gear 22a of the driven gear 22. As a result, the rotational force of the drive gear 11 is
It is transmitted from b to the small spur gear 22a of the driven gear 22 via the intermediate gear 31, and the low speed operation of the main shaft 21 is obtained.

On the other hand, in order to shift from medium speed operation to high speed operation, pressure oil is supplied to the cylinder chamber 24a and pressure oil is discharged from the cylinder chambers 25b and 25c. The idler shaft 32 is moved further to the right from the illustrated state, and the small spur gear 11a of the drive gear 11 and the intermediate gear 3
While the 1 middle spur gear 31b meshes, the small spur gear 31a of the intermediate gear 31 and the small spur gear 22b of the driven gear 22 simultaneously mesh,
High-speed operation of the spindle 21 can be obtained.

As described above, according to the present embodiment, the idler shaft 32, on which the intermediate gear 31 is rotatably supported, is reciprocally moved in the axial direction by using the hydraulic piston / cylinder mechanism provided at both ends thereof to drive the drive gear 11 and the driven gear. It is possible to change the rotational speed by changing the meshing relationship with the gear 22. Further, the float piston 36 is loosely fitted to one end of the idler shaft 32, and the float piston 36 is moved toward the other side of the idler shaft 32 to move the idler shaft 32 to an intermediate position. It can be stopped in the high-speed driving position.

According to the present embodiment, the intermediate gear 31 only rotates with respect to the idler shaft 32 via the bearing 35, and there is no place where metal friction may occur during rotation unlike the conventional case. Therefore, it is not necessary to inject a large amount of lubricating oil for preventing the generation of frictional heat as in the conventional case, and the amount of heat generation can be extremely reduced. Further, it suffices to provide the cylinders 24 and 25 for slidably holding the idler shaft 32 at both ends thereof, and it is not necessary to provide a guide plate and a hydraulic cylinder for driving the guide plate as in the conventional case, and the structure is simple. Easy to assemble.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a rotation speed transmission that has no heat generating portion that has a thermal effect, has a simple structure, and is easy to assemble.

INDUSTRIAL APPLICABILITY The present invention is not limited to the rotation speed transmission device of the main shaft of a machine tool, but can be widely applied to a gear type rotation speed transmission device that shifts the rotation speed by shifting an intermediate gear.

[Brief description of drawings]

The drawing is a cross-sectional view showing an example in which the rotational speed transmission according to the present invention is applied to a spindle of a machine tool. 11 ... Drive gear, 21 ... Main shaft, 22 ... Driven gear, 24, 25 ... Cylinder, 26, 27, 28 ... Oil port, 31 ... Intermediate gear, 32 ... Idler shaft, 33, 34 ... Idler shaft end, 36 ... Float piston.

Claims (2)

[Claims] 1. A drive gear, a driven gear, and an intermediate gear, each of which is formed by continuously connecting a plurality of spur gears having different numbers of teeth, such that the intermediate gear can mesh with the driving gear and the driven gear at the same time. In the device for changing the meshing position of each gear by moving the intermediate gear in the rotation axis direction to change the rotation speed of the driven gear, both ends of the intermediate gear are opposed to each other. Is rotatably supported by an idler shaft slidably inserted into and held in two cylinders arranged in parallel with each other, and a pressure fluid supply source is connected to each of the cylinders via a direction switching valve. A rotation speed transmission device characterized by the above. 2. A large-diameter portion and a small-diameter portion are formed at one end of the idler shaft, and a float piston that slides in a fixed cylinder is loosely fitted to the small-diameter portion. The rotation speed transmission according to claim 1.