RU2268816C2 - Elongated article cylindrical grinding method and rest - Google Patents

Abstract

FIELD: machine tool manufacture, possibly cylindrical grinding of elongated and thin articles such as rolls.

SUBSTANCE: method comprises steps of mounting article in center; basing it on main bearing units of rest; at starting each technological pass, placing table with article in limit position; driving article to rotation; crosswise feeding tool and forming on worked surface collar with depth 5 - 50 micrometers; basing article by means of collar on bearing units of rest and working surface at guaranteed pressing of article to main bearing units; selecting pressure effort value depending upon rigidity of article at deformation preventing condition. Rest is mounted in housing and it includes except main bearing units (one main bearing unit is horizontal) floating bearing unit for providing guaranteed pressing of article to main bearing units. Floating bearing unit includes holder and tightening mechanism joined with holder. The last is mounted with possibility of radial motion relative to rotation axis of article and it is arranged in body of rest at side opposite to main bearing units. Horizontal bearing unit includes self-aligning member whose step number and angle parameters are selected according to condition minimizing influence of out-off-roundness upon positional stability of article rotation axis.

EFFECT: improved roundness degree of elongated articles such as rolls at cylindrical grinding in centers, enhanced efficiency of grinding.

2 cl, 3 dwg

Description

The invention relates to the field of machine tools, namely to grinding, and can be used for round grinding of long and thin products such as rolls installed in the centers.

A known method of surface treatment of products such as rings and lunettes (RU No. 2145917, 23 V 1/00, 24 V 1/00, B 23 Q 1/76, 02.22.1999). The method of processing the surface of rotation of the product includes basing the product on at least one lunette, bringing the product into rotation and processing the surface of rotation of the tool in at least two stages, in the first of which an auxiliary belt is formed on the product, and in the second, processing the surface of rotation based on the backrest on the auxiliary belt, and differs in that when forming the auxiliary belt, the product is based on the surface of rotation to be processed, while for base use comfort backrest with self-aligning bearings. The lunette contains a housing with the main supports in the form of prisms and at least one auxiliary support for weight compensation and is characterized in that it is equipped with a slider and a rocker mounted in the housing of the lunette with the possibility of rotation around the axis and vertical movement, and the main supports are pivotally mounted on the axes at the ends of the rocker arm, and the auxiliary support is made in the form of a similar prism and mounted on a slider pivotally or motionless, and the slider is located at an angle to the vertical and mounted linearly movement in the lunette body.

A known method of chamber abrasive treatment and a device for its implementation (RU No. 2218262 24V 31/10, 03/18/2002). The invention is intended for grinding and polishing long smooth shafts, worms, screws. According to the invention, an abrasive pressure on the surface being machined is created that is variable along the length of the chamber and the chamber is forced to cyclicly move along the axis of the part. Processing modes depend on the type of workpiece.

When machining long products in the centers of, for example, long rolls with a grinding wheel, insufficient rigidity of the product, the axiality of its axis causes instability of the cutting forces during rotation of the product, which leads to a violation of the geometric accuracy of the processed surface (barrel-shaped, non-circularity). In addition, productivity decreases, since when processing such products to obtain a given geometric accuracy, it is necessary to carry out multiple passes.

To solve this problem, additional supports are used - lunettes, which are installed between the centers.

Known lunette (RU No. 2179916 B 23 Q 1/76, 02/09/2000). It is used on metal cutting machines when processing non-rigid parts to increase the accuracy of centering of workpieces. The lunette contains a slider and a slider connected through a rack-and-pinion mechanism. Four roller bearings are fixed on the sliders. The lunette also contains a node for fine-tuning the roller bearings.

A well-known lunette grinding machine (RU No. 2008164 23 Q 1/24, 01/30/1992). It is used in the round grinding of products subjected to oblique bending due to their inhomogeneous stiffness in the cross section, for example, when grinding the necks of the crankshaft. The lunette contains two interconnected levers mounted with the possibility of movement, bearing jaws acting on the neck to be sanded. The supply of both jaws is carried out by one feeding mechanism; the second arm of the lever carrying the lower jaw also rests on the adjustment screw. The supply of the lateral sponge to the neck forces the lower sponge to be brought in.

The known solutions described above partially solve the problem of eliminating barrel-shapedness and increasing productivity and do not effectively reduce the non-circularity caused by the non-linearity of the product axis.

The tasks that are solved by the inventions are to increase the roundness of long products with round grinding of products (such as rolls) installed in the centers, and to increase processing productivity.

The tasks are solved as follows. The method of round grinding of long products includes installing the product in the centers, basing the product on the main supports of the rest, bringing the product into rotation and processing the surface of rotation with a tool, and differs in that at the beginning of each process pass the table with the product is set to the extreme position, then the product is rotated make a transverse feed of the tool and form a girdle with a depth of 5-50 microns on the surface to be treated, after which the girdle is based on the main supports of the lunette and surface treatment with guaranteed clamping of the product to the main supports of the rest, and the amount of clamping force is selected depending on the rigidity of the workpiece, provided that all its deformations are excluded, if necessary, repeat the treatment.

The lunette contains a body with two main supports, one of them horizontal, and is characterized in that the lunette case is mounted on a bed, a floating support is additionally introduced, which ensures guaranteed clamping of the product to the main supports of the lunette, while the said support consists of a clamp with a platform associated with the mechanism of its interference. The clamp is mounted with the possibility of radial movement relative to the axis of rotation of the part and is located in the lunette case on the side opposite to the main supports, and the amount of clamping force is selected depending on the rigidity of the workpiece, provided that all its deformations are excluded. The horizontal support is a self-supporting support, the number of steps and parameters (angles) of which are selected from the condition of minimizing the influence of non-circularity on the stability of the position of the axis of rotation of the product.

The proposed invention is illustrated by drawings. Figure 1 shows the design of the lunette, figure 2 is a top view of the machine when grinding the product, figure 3 is the design of the lunette with a self-supporting support.

The machine for processing a lengthy product contains a fixed bed 1, on which a table 2 is longitudinally movably mounted on the rails. The workpiece (roll) 3 is installed in the centers of the front and rear headstock located on the table, additionally based on the main supports of the lunette, grinding is performed with a grinding wheel 4 . The rest is installed motionlessly on the bed 1 opposite the grinding wheel.

The lunette is a body 5, in which the main supports are mounted - the central (horizontal) 6 and lower 7 sliders, installed with the possibility of horizontal movement. The central slider 6 is located opposite the grinding wheel. The lower slider 7 is in contact with the lever 8, which is mounted on the housing 5 with the possibility of angular rotation about an axis parallel to the axis of the product. On the central slider 6, a fixed support platform 9 or a self-aligning support 13 is installed (Fig. 3), on a lever 8, a fixed support platform 10, on which the workpiece is based. In the support 13, the number of steps and the parameters (angles) of the support are selected from the condition of minimizing the influence of non-circularity on the stability of the position of the axis of rotation of the product.

Deformation (deflection) of the long roll installed in the centers leads to the fact that during its processing the clamping forces of the product to the supporting platforms 9 and 10 change, which negatively affects the steepness of the workpiece, increases the number of passes. To ensure a stable force of pressing the product to the supporting platforms (mainly to the horizontal supporting platform 9) during its processing, a device is added to the lunette in order to ensure guaranteed pressing of the product to the supporting platforms.

This device is a floating support consisting of a clamp 11 with a support platform 12 and an interference mechanism of the clamp assembly. The clamp 11 is mounted with the possibility of radial movement relative to the axis of rotation of the part 3. The floating support is mounted on the body 5 of the lunette and is located (relative to the center of rotation of the product) on the side opposite to the supporting platforms 9 and 10. The clamp of the supporting platform 12 to the product 3 is carried out by means of an interference mechanism - springs (other well-known options for creating an interference fit 11 are also possible, for example, using hydraulics, under the influence of weight). The clamping force of the floating support to the part is directed perpendicular to the axis of rotation of the product, the force value is selected depending on the rigidity of the workpiece, provided that all its deformations are guaranteed to be excluded.

The above-described construction of the lunette can be used for turning (with certain modifications, taking into account the direction of cutting forces) and round grinding of long products.

The processing of the product is as follows.

The product is installed in the centers of the front and rear headstock of the table. At the beginning of each passage, the table with the product is set to the extreme position. Then the product is rotated. Make a transverse feed of the tool (grinding wheel) and form a girdle with a depth of 5-50 microns on the treated surface. The roundness of the polished surface is determined by the high rigidity and quality of the back center of the machine and the quality of the center holes of the product. Then, supporting platforms 9 and 10 of the rest are brought to the surface of the girdle until they are in close contact with the workpiece. Install a floating support and provide guaranteed clamping of the product to the supporting platforms. Turn on the longitudinal table feed and perform a technological passage.

The support platforms of the lunette slide along the previously machined front cutting edge of the grinding wheel of the roll surface, which has a circularity close to that of the polished belt.

If necessary, repeat the passage. Several consecutive passes, similar to those described above, ensure the roundness of the product, close to the roundness of the center holes and centers (usually in the range of 0.5-1.5 microns).

The above-described method of circular grinding of long products in the centers and rests has several advantages:

- excludes the influence of the directness of the axis of the product on the roundness of the treated surface,

- provides a stable high rigidity of the product in the processing zone due to the constant clamp created by the floating support at the junction of the surface of the product and the supporting platforms of the lunette.

The above-described construction of the lunette can be used for turning and round grinding of long products, for example, rolls installed in the centers.

Claims (2)

1. The method of circular grinding of long products, including installing the product in the center, basing the product on the main supports of the rest, bringing the product into rotation and processing the surface of rotation with a tool, characterized in that at the beginning of each process pass the table with the product is set to the extreme position, then the product they are rotated, the tool is transversely fed, and a belt is formed on the surface to be machined with a depth of 5-50 μm, after which the product is based on a belt support on the rest and performed surface Botko nip while guaranteeing the product to the main backrest supports, wherein the magnitude of the contact force is selected depending on the hardness of the workpiece with the deletion strains, processing is repeated as necessary. 2. A rest for circular grinding of lengthy articles, comprising a case mounted on the machine table with two main supports, one of which is horizontal, characterized in that a floating support is additionally introduced into it, which ensures guaranteed clamping of the product to the main supports of the rest and consisting of a clamp connected with the mechanism of its interference, while the clamp is mounted with the possibility of radial movement relative to the axis of rotation of the part and is located in the body of the lunette from the side opposite to the main supports, and led rank force guaranteeing clamp the article to the main supports, chosen depending on the rigidity of the workpiece deformation exception conditions, wherein the horizontal support comprises a caster support, the number of steps and the parameters - which angles are chosen from the condition of minimizing the influence on the stability roundness rotation axis position of the product.

Images