FR2831474A1 - Grinding device for super finishing of pinion teeth comprises grindstone and tool holder carriage supporting pinion, grindstone comprising drum with several discs having annular periphery sized to teeth profile - Google Patents

Abstract

The grinding device for the super finishing of the teeth of a pinion (12) comprises a rotating grindstone (16) and a tool holder carriage (14) supporting the pinion. The grindstone comprises a drum (18) rotating about an axis (20) and comprising several discs whose annular periphery is sized to the profile of the teeth. The pinion is mounted to rotate freely between a counter point (24) and a point (26) integral with the tool holder carriage. The carriage is driven in a first alternate rectilinear movement orthogonal to the grindstone rotational axis and a second alternate rectilinear movement extending parallel to the rotational axis in order to use the grindstone as a rack rotating the pinion.

Description

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Grinding device for superfinishing the toothing profile of the pinions.

Technical Field of the Invention The invention relates to a grinding device for superfinishing the toothing profile of a pinion, comprising a rotary grinding wheel with elastic binder made of elastomeric material, and a tool carriage supporting the pinion to be rectified. .

STATE OF THE ART In order to reduce the noise generated by gear mechanisms rotating at increasingly high speeds, it is necessary to improve the surface condition of the toothing of the pinions and the gears.

Some manufacturers have developed improvement systems after cutting, in particular profile correction and lapping of teeth by honing.

These finishing operations are long and costly.

OBJECT OF THE INVENTION The object of the invention consists in producing an improved grinding device making it possible to obtain a smooth surface condition of the gear profile of the pinions in a very short time and at a reduced cost.

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The device according to the invention is characterized in that: - the grinding wheel comprises a drum mounted for rotation about an axis, and comprising a plurality of elementary grinding discs the annular periphery of which is cut to the tooth profile of the pinion, - the pinion is mounted free in rotation between a tailstock and a point secured to the tool-holder carriage, which is driven by a first reciprocating rectilinear movement orthogonal to the axis of rotation of the grinding wheel to cover the length of the pinion, and a second reciprocating rectilinear movement extending parallel to the axis of rotation to use the grinding wheel as a rack by driving the pinion in rotation.

According to a preferred embodiment, the carriage is associated with a first actuator to define the stroke of the first reciprocating rectilinear movement, to a second actuator to define the course of the second reciprocating rectilinear movement. The first actuator and / or the second actuator are advantageously formed by hydraulic or pneumatic cylinders.

According to a characteristic of the invention, the elastic binder used for the manufacture of grinding discs for the grinding wheel is an elastomeric material having a Shore hardness of between 50 and 120, preferably between 70 and 90.

A fixed guide is equipped with a toothed sector placed next to an end disc of the grinding wheel, and cooperating with the pinion to be ground to synchronize its speed of rotation before the introduction of the ground discs.

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SUMMARY DESCRIPTION OF THE DRAWINGS Other advantages and characteristics will emerge more clearly from the description which follows of an embodiment of the invention given by way of nonlimiting example, and represented in the appended drawings in which: - Figure 1 is a schematic view of the grinding device according to the invention; - Figure 2 shows a plan view of Figure 1.

Description of a preferred embodiment In FIGS. 1 and 2, a grinding device 10 for superfinishing the toothing profile of a pinion 12 with trapezoidal teeth, comprises a workpiece carriage 14 supporting the pinion 12 to be ground, and a grinding wheel 16 with elastic binder, intended to obtain a smooth surface condition of the teeth of the pinion 12.

The grinding wheel 16 is constituted by a drum 18 mounted for rotation about an axis 20, and comprising a plurality of elementary grinding discs 22 whose annular periphery is cut to the toothing profile of the pinion 12. The discs 22 have identical structures , and are staggered at regular intervals along the direction of the axis of rotation 20.

The grinding wheel 16 in plan view in FIG. 2 is shaped according to a rack, coming to mesh with the radial teeth of the pinion 12. The rotary grinding wheel 16 remains fixed relative to the movable workpiece carrier 14.

The pinion 12 is mounted to rotate freely between a tailstock 24 and a tip 26, while being driven by a first reciprocating rectilinear movement indicated by the arrow F2. For this purpose, the support of the tip 26 is integral with the

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 workpiece carriage 14, which is driven by a first actuator 28 to define a beat zone of the pinion 12.

The actuator is constituted by hydraulic or pneumatic cylinder 28, which is associated with a proportional action valve (not shown), or controlled by a digital or analog control circuit. The adjustment of the top and bottom dead centers of the stroke is carried out either by coding wheels, or by selection with dimension display.

According to a variant (not shown), the flapping mechanism according to F2 can be produced differently, for example by means of a connecting rod device.

To achieve flexible rectification of the teeth, the elastic binder used for the manufacture of the discs 22 of the grinding wheel 16 is an elastomer material having a Shore hardness of between 50 and 120. Preferably, an elastomer having a hardness of between 70 will be chosen. and 90 to obtain an optimum buffing effect.

A fixed guide 32 is equipped with a toothed sector 30, which is placed next to a disc 22 at the end of the grinding wheel 16. The toothed sector 30 engages in priority on the pinion 12 to be rectified to synchronize its speed of rotation before the introduction of the grinding discs 12 of the rotary grinding wheel 12. The ends of the discs 22 then constitute a rack causing the pinion 12 to rotate.

The pinion 12 is rotated by means of a second actuator 34 moving the workpiece carrier 14 in a second reciprocating rectilinear movement indicated by the arrow F3, and extending parallel to the axis of rotation 20 of the grinding wheel 16 , and orthogonally to the first alternative rectilinear movement indicated by the arrow F2.

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FIG. 2 shows different positions of the carriage 14 relative to the grinding wheel 16.

In the extreme position A of the carriage 14, the pinion 12 is located at point A 1 upstream of the toothed sector 30.

In the intermediate position B of the carriage 14, the speed of the pinion 12 is synchronized following the intervention of the toothed sector 30, and is in 81 engaged with two intermediate discs 22. The reaction of the teeth of the pinion 12 with the rack of the grinding wheel 16 causes the natural rotation of the pinion 12.

In the extreme position C of the carriage 14 located opposite A, the pinion 12 is engaged with the last disc 22 of the grinding wheel 16.

The flapping movement according to arrow F2 makes it possible to cover the total length of the flanks of each tooth of the pinion 12 so as to obtain a uniform smooth surface condition following the polishing of a rotary disc 22. The passage from one tooth to the other is automatic since the grinding wheel 16 also serves as a fixed rack for driving the pinion 12 in rotation during the simultaneous intervention of the second actuator 34. The following disc 22 will then rectify, and so on until the last tooth of the pinion 12.

The flexible rectification implemented in the device 10 according to the invention lasts less than a minute for a pinion having a diameter of the order of 3 cm. During the operation, use is made of a cooling liquid (water and oil mixture) sprayed towards the area to be corrected by the pinion 12.

The device 10 according to the invention also applies to the superfinishing of the toothing profile of the toothed wheels and gears.

Claims (7)

Claims 1. Grinding device for superfinishing the toothing profile of a pinion (12), comprising a rotary grinding wheel (16) with elastic binder made of elastomeric material, and a tool carriage (14) supporting the pinion (12) to be ground, characterized in that: - the grinding wheel (16) comprises a drum (18) mounted for rotation about an axis (20), and comprising a plurality of elementary grinding discs (22) whose annular periphery is cut to the pinion toothing profile (12), - the pinion (12) is mounted to rotate freely between a tailstock (24) and a tip (26) integral with the tool-carrying carriage (14), which is driven by a first reciprocating rectilinear movement (arrow F2) orthogonal to the axis of rotation (20) of the grinding wheel (16) to cover the length of the pinion (12), and of a second rectilinear movement a! temative (arrow F3) extending parallel to the axis of rotation (20) to use the grinding wheel (16) as a rack by driving the pinion (12) in rotation. 2. Grinding device according to claim 1, characterized in that the carriage (14) is associated with a first actuator (28) to define the stroke of the first reciprocating rectilinear movement. 3. Grinding device according to claim 1 or 2, characterized in that the carriage (14) is associated with a second actuator (34) to define the stroke of the second reciprocating rectilinear movement. <Desc / Clms Page number 7>  4. Grinding device according to claim 2 or 3, characterized in that the first actuator (28) and / or the second actuator (34) are formed by hydraulic or pneumatic cylinders. 5. Grinding device according to claim 2, characterized in that the first actuator (28) is constituted by a connecting rod-crank device. 6. Grinding device according to one of the preceding claims, characterized in that the elastic binder used for the manufacture of discs (22) for grinding the grinding wheel (16) is an elastomeric material having a Shore hardness of between 50 and 120 , preferably between 70 and 90. 7. Grinding device according to one of the preceding claims, characterized in that a fixed guide (32) is equipped with a toothed sector (30) placed next to a disc (22) at the end of the grinding wheel (16), and cooperating with the pinion (12) to be rectified in order to synchronize its speed of rotation before the introduction of the grinding discs (22).