RU2212325C2 - Method of massive work alignment at machining position - Google Patents

Abstract

FIELD: metal machining by cutting, particularly, methods of installation of large-sized heavy works, mainly, on work tables of metal-cutting machine tools. SUBSTANCE: method includes installation of work with its bearing surface on auxiliary supports regulated in height and located on machine tool table. Use is made of three auxiliary supports located near to edges of work bearing surface under conditions of maximum sagging in definite places; alignment of each sagging work part distant from auxiliary supports by means of support regulated in height; bringing of measuring heads in contact with work bearing surface in places of location of auxiliary supports regulated in height and readings of measuring head installed in place of location of regulated support are initially registered. In alignment, sagging part of work, first, is raised to position at which reading of one of measuring head installed in places of location of auxiliary supports begins to change, and in this position, reading of said measuring head is registered again, and then, lowered through value equaling half of difference between the first and second readings of measuring head. EFFECT: reduced labor input, higher accuracy of alignment directly on machine tool table of, both, parts on intermediate operations and of nonmachined works without limiting their dimensions and weight. 3 dwg

Description

 The invention relates to the processing of metals by cutting, and in particular to methods of installing large-sized heavy workpieces, mainly on the tables of metal cutting machines.

 Known methods for reconciling massive workpieces at a processing position, for example, on a table of a metal cutting machine, on which the workpiece is mounted by a supporting surface on three technological supports (the minimum required number of supports determining the horizontal position of the body), and then using those height-adjustable supports raise those parts of the workpiece that sag under their own weight due to the distance from the supports (Balakshin BS Fundamentals of mechanical engineering technology. - M.: Mechanical Engineering, 1969, p.142, Fig. 90).

 However, such methods do not provide a sufficiently high accuracy of reconciliation, since with an uneven supporting surface of the workpiece — and this is most often casting — there are no guidelines that allow us to judge reliably the necessary amount of lifting the sagging sections of the workpiece to a neutral position, i.e. to a position that would take a verified surface, if the workpiece was in a state of zero gravity. Therefore, sagging sections of the workpiece are aligned "by eye". As a result of this, the accuracy characteristics of the workpiece planes are reduced.

 The closest in technical essence is the method of installing large parts (ed. Certificate of the USSR 1348128, 23 Q 3/00, 1987), in which the part is placed on adjustable legs mounted on the machine table, which are set to the required height for their interaction with the installation the surface of the part, followed by fixing the part. Before placing the part on the adjustable table supports, it is suspended with the possibility of rotation around the vertical axis and combining the plane of its maximum rigidity with the vertical plane, the part is brought by weight with the mounting surface to the vertical coordinate plane until it contacts the fixed stops and the distance from the vertical coordinate plane to the installation is measured the surface of the part in places of its contact with the adjustable table supports for their subsequent adjustment.

 However, when using the known method, the reason that impedes obtaining the required technical result is the high complexity of the process of alignment and installation of the workpiece, moreover, the known method does not provide the necessary accuracy of the alignment of the workpiece, which reduces the accuracy characteristics of the machined part. In addition, the known method is suitable for reconciling only relatively small workpieces with the simplest geometry, because it requires a vertical reference plane, commensurate in size with the dimensions in terms of the workpiece being verified, which is not always feasible. For long (of the order of 10 m or more) workpieces with a slightly pronounced stiffness on the edge (for example, a bed of lathes), the known method is generally not suitable.

 The high complexity is due to the fact that the known method requires hanging the workpiece on the ropes with careful alignment, accurate measurements and the exhibition of supports for these measurements, a very difficult installation of the workpiece on the machine table so that the measurement sites precisely fit onto the supports. The supporting surface (at least in the places of measurements) must be carefully pre-processed, since the measurement is carried out at a certain point on the surface of the workpiece, and the machine support is in contact with this surface in area - on the untreated surface, the relief on this area is significantly different from measuring points.

Errors are possible for each operation of the reconciliation process:
- introduced by deviations from the flatness of the reference plane;
- measurements of distances from the reference plane;
- introduced by bends of a suspended workpiece, especially in workpieces without pronounced stiffness on the rib and in workpieces of complex configuration;
- exhibitions of supports on the machine table;
- non-alignment of measurement points with supports on the table.

 The listed (and other) errors, summing up, affect the results of the reconciliation - the actual position of the workpiece on the table differs significantly from the ideal position (as in zero gravity). And this, in turn, negatively affects the accuracy characteristics of the finished part.

 The technical result is aimed at reducing the complexity and increasing the accuracy of the alignment directly on the machine table of both parts in intermediate technological operations and completely unprocessed blanks (castings), without limiting the dimensions and weight.

 The technical result is achieved by the fact that in the method of reconciling massive workpieces at the processing position, including installing the workpiece with a supporting surface on technological and height-adjustable supports located on the machine table, according to the invention, three technological supports are used that are located near the edges of the workpiece supporting surface from the condition of greatest sagging in certain places, and reconcile each sagging part of the workpiece remote from the technological supports by means of adjustable the height of the support, while at the locations of the technological and adjustable supports, the measuring heads are brought into contact with the supporting surface of the workpiece and the measurement head is first recorded at the location of the adjustable support, and when reconciling, the sagging part of the workpiece is first raised to a position at which it begins to change the reading of one of the measuring heads installed in the locations of the technological supports, and in this position, the reading of said measurement is recorded a second time body head, and then lowered by an amount equal to half the difference between the first and second recorded readings of the measuring head.

 Distinctive features of the prototype is that they use three technological supports, which are located near the edges of the support surface of the workpiece from the conditions of greatest sagging in certain places, and reconcile each sagging part of the workpiece remote from the technological supports by means of a height-adjustable support, while at the locations technological and adjustable supports are brought into contact with the supporting surface of the workpiece measuring heads and initially record the reading of the measuring of the trap installed at the location of the adjustable support, and when reconciling, the sagging part of the workpiece is first raised to a position at which the reading of one of the measuring heads installed in the locations of the technological supports begins to change, and in this position the reading of the said measuring head is recorded a second time, and then lower by an amount equal to half the difference between the first and second recorded readings of the measuring head.

 In FIG. 1 schematically shows the setup for implementing the method (the configuration of the workpiece is simplified shown in the form of a parallelepiped); in FIG. 2 shows a top view of the workpiece, diamonds indicate the projection of the location of the technological supports on the upper surface of the workpiece, oblique crosses - the projection of additional supports; figure 3 - the position of the console part of the workpiece at different stages of the implementation of the method.

 A massive bulky workpiece is mounted on a table 2 of a metal cutting machine (at the machining position), having its supporting surface 3 on three technological supports 4-6 (three supports are the minimum number required to fix the workpiece in a horizontal plane).

 Supports 4-6 are fixed on the table 2 in this case so that the surface 3 of the workpiece 1 is in contact with them near its edges by the three corners of the rectangle (see figure 2).

 With this arrangement of the supports 4-6, the workpiece 1 under the influence of its own weight will certainly sag in places remote from the supports. Obviously, the maximum sagging (how specific is it necessary to know is optional) will occur in the places farthest from the supports, on the fourth corner of the workpiece, as well as in the middle part of the workpiece between the supports 4 and 6, 5 and 6 (these places are indicated oblique in Fig. 2 crosses).

 Under the sagging fourth corner of the workpiece 1 (position "a" in Fig. 3), an additional jack height-adjustable support 7 of the type is installed. Then, on each of the supports 4-6 and on the support 7, indicator-type measuring heads 8 mounted on racks are installed (for example, IPM heads according to GOST 28798-90) and their tips are brought into contact with the upper surface of the workpiece 1 (if the heads 8 are installed above the workpiece difficult or impossible, then the heads can be located under the workpiece - as close as possible to the corresponding support. In this case, the tips of the measuring heads are in contact with the bottom surface of the workpiece 1).

 After that, the reading of the measuring head located above the additional support 7, i.e. the indication that the head has when the position “a” of the part of the workpiece, naturally bent under the action of gravity (readings of other heads are not necessary to read).

 Then, using the support 7, used as a jack, the sagging part of the workpiece 1 — in this case, its angle — is gradually raised (bent), while observing the arrows of the measuring heads 4-6. The lifting is stopped as soon as on one of them (most likely on the nearest head of the support 6) the arrow that was still stationary “came to life”, i.e. budged. This means that the raised part of the workpiece has reached position “b” (FIG. 3), at which the bending deformation has reached the support 6, i.e. the cantilever part of the workpiece 1 bent up to the same extent (by the same amount) as it sagged before lifting, when the first reading of the measuring head was made above the support 7. In this position (position "b" in figure 3) register the second time the reading of the head above the support 7.

 The difference between the first and second readings is divided in half and the raised part of the workpiece 1 is lowered by the found value using the same support 7 (position "c" in figure 3).

 Thus, the workpiece 1, previously sagging under the natural action of its own weight and then artificially bent up to the same extent as it sagged (imitation of natural sagging, but with the opposite sign), now occupied the middle neutral position "in", ie a position that it would have been without any external forces and gravitational forces acting on it.

 In this position, the additional support is fixed, and it becomes a technological support for the workpiece.

 After that, if necessary, the process is repeated on other sagging parts of the workpiece 1, for example, in places 9 and 10 (Fig. 2), each time introducing a new additional support into the setup and installing an additional measuring head above (or below) this place. This need arises if the amount of slack affects the accuracy of subsequent machining. Thus, the workpiece is calibrated until all of it is in a neutral position, as if being in zero gravity (as a rule, four to six supports are sufficient so that the sections between them do not sag outside the tolerance area on the flatness of the surface to be machined )

 Thus, the inventive method allows accurate reconciliation of any size and configuration of the workpiece, without using any additional planes, directly at the processing position, which significantly reduces the complexity of the reconciliation.

Claims (1)

 A method of reconciling massive workpieces at a processing position, including installing the workpiece with a supporting surface on technological and height-adjustable supports located on the machine table, characterized in that three technological supports are used, which are located near the edges of the workpiece supporting surface from the condition of greatest sagging in certain places, and carry out the reconciliation of each sagging part of the workpiece remote from the technological supports by means of a height-adjustable support, while at the locations of those of technological and adjustable supports, the measuring heads are brought into contact with the support surface of the workpiece and the measurement head is first recorded at the location of the adjustable support, and when reconciling, the sagging part of the workpiece is first raised to a position at which the reading of one of the measuring heads installed in locations of technological supports, and in this position the readings of the said measuring head are recorded a second time, and then lowered by equal to half the difference between the first and second readings of the measuring head.

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