GB2188450A

GB2188450A - Machine for operating on a workpiece and method of setting the machine

Info

Publication number: GB2188450A
Application number: GB08607316A
Authority: GB
Inventors: Arthur Neil Brown
Original assignee: BRONX ENGINEERING Co LIMI
Current assignee: BRONX ENGINEERING Co LIMI
Priority date: 1986-03-25
Filing date: 1986-03-25
Publication date: 1987-09-30
Anticipated expiration: 2006-03-25
Also published as: GB8607316D0; GB2188450B

Abstract

Settings of adjustable elements of a tube straightening machine are computed by control means which has a memory containing settings used on previous occasions. The control means computes theoretical settings according to a formula and then varies these by amounts extrapolated or interpolated from the contents of the memory. <IMAGE>

Description

SPECIFICATION Machine for operating on a workpiece and method of setting the machine Description of Invention The present invention relates to the setting of a machine for operating on a workpiece and has been devised for use in connection with a machine which is to operate, at different times, on workpieces which differ from one another in respect of at least one characteristic. The machine may be a machine which is alters the shape of each workpiece, either by cutting away material or deforming the workpiece or both. The invention will be explained hereinafter with reference to a machine for deforming workpieces but it is to be understood that the invention is of more general application.

An example of a process which involves deforming workpieces which differ from one another in at least one characteristic is the straightening of metal tubes. There are commonly used for this purpose straightening machines having three pairs of mutually opposed rolls, the pairs being spaced apart along a path of travel of the tube through the machine. The axis of each roll is inclined at acute angle to the length of the path and the angle of inclination of each roll may differ from the angles of inclination of the other rolls. These angies of inclination are adjusted according to characteristics of the tubes to be straightened.The gap between the rolls of each pair also is adjusted according to characteristics of the tube to be straightened and a further adjustment which must be made is the offsetting of a point mid-way between the rolls of the middle pair from a straight line joining the corresponding points associated with the upstream and downstream roll pairs.

The process of straightening the tube can involve reducing the diameter of the tube to a value which is uniform along substantially the entire length of the tube, correcting ovality of the tube and correcting divergence of a longitudinal axis of the tube from a straight line.

To achieve the best possible quality of the tube in each of these respects, optimum values must be selected for the various settings of the machine.

Prior to the present invention, selection of optimum settings of a six-roll straightening machine has been entirely dependant on the skill of the operator. A skilled operator will maintain a record of the settings used for tubes having particular characteristics and which have been straightened previously. He will use this record as a guide to the selection of appropriate settings. Although theoretical settings can be calculated, it is found that the use of theoretical settings does not achieve optimum quality of the tube produced. It is necessary to depart from the theoretical set tings and the selection of the optimum depar ture for each setting is regarded as an art, rather than as a science. It has not been found possible to formulate rules or formulae which will enable the most appropriate set tings to be selected.

According to a first aspect of the present invention, there is provided a method of set ting a machine for operating on a workpiece wherein information defining one or more characteristics of the workpiece is applied to control means of the machine, the control means computes a theoretical setting of one or more settable elements of the machine ap propriate to the characteristic or character istics applied, the control means computes an actual setting of the or each of said elements by varying the theoretical setting by an amount interpolated from or extrapolated a re cord of variations previously applied to theore xical settings for other workpieces and the control means provides a signal representing the computed actual setting to adjustment means which adjusts the element accordingly.

In a case where the machine is to be used for straightening a metal tube, the information applied to the control means would represent one or more of the external diameter of the tube, the wall thickness of the tube and the tensile yield of the tube. The yield strength of the tube may be represented by a designation of the quality of the tube or the yield strength at normal temperatures, together with the temperature of the tube during straightening.

The control means may be provided, prior to straightening of any tube by the machine, with a set of information comprising actual settings believed to be suitable for tubes hav ing certain, defined characteristics so that the control means will be able to interpolate from this set of information to compute settings for the first tube to be straightened. The actual setting used for straightening that tube also will be incorporated into the set of information so that the set of information will grow during the use of the machine.

The actual setting of one or more than one of the elements may be further varied by the operator. In this case, the record of variations previously applied is preferably a record of the variations achieved by combining with the var iations interpolated by the control means the additional variations imposed by the operator.

According to a second aspect of the inven tion, there is provided apparatus comprising a machine having at least one adjustable ele ment for operating on a workpiece and adjust ment means for setting the adjustable element in a selected position and further comprising control means associated with the adjustment means to provide thereto a signal representing the selected position or representing an ad justment required to achieve the selected posi tion, wherein the control means includes input means for receiving data defining one or more characteristics of a workpiece, computation means for computing a theoretical setting of said element according to a predetermined formula and the data defining one or more characteristics of the workpiece and a memory containing a record of variations from previously computed theoretical settings of actual settings used in operating on previous workpieces, the computation means being programmed to interpolate from the record variations appropriate to said data and to combine said variations with the computed theoretical setting to define the selected position.

The control means preferably runs a programme which includes the step of comparing the data applied to the control means with data stored in the memory and, if the data applied to define the characteristics of a particular workpiece is found to coincide with the characteristics of a workpiece operated upon previously, to adopt as the actual settings the previously used settings or to adopt as the variations to be applied to the theoretical settings the variations previously applied.

An example of a method embodying the first aspect of the invention and of a machine in accordance with the second aspect of the invention will now be described, with reference to the accompanying drawings, wherein: Figure 1 represents diagrammatically certain parts of a tube straightening machine; and Figure 2 is a flow chart representing operation of control means of the machine.

The machine includes a frame comprising a base 10 and an upper part 11 connected by a number of vertical columns 12. There is mounted on the base near to one end thereof a first roll carrier 13 rotatably supporting a first roll 14 with the axis of the roll horizontal.

The carrier is rotatable relative to the base about a vertical axis which passes through the centre of the roll 14 but connot move upwardly or downwardly relative to the base.

Adjustment means comprising an electric motor is provided for adjusting the carrier 13 and roll 14 about the vertical axis relative to the base.

A second carrier 15 is mounted on a beam 16 which is slidable upwardly and downwardly on four of the columns 12. Further adjustment means comprising an electric motor and screw and nut mechanisms is provided for moving the beam 16 upwardly and downwardly relative to the base. The carrier 5 is mounted on the beam for turning relative thereto about a vertical axis 17 which coincides with the axis of rotation of the carrier 13 relative to the base 10. Further adjustment means is provided for turning the carrier 15 about the axis 17 relative to the beam. A second roll 18 is mounted on the carrier 15 for rotation relative thereto about a horizontal axis. Drive means is provided for rotating the rolls 14 and 18.

The rolls 14 and 18 constitute a first roll pair and there is a second roll pair 19, 20 arranged in a corresponding manner adjacent to the other end of the machine. A third roll pair 21, 22 is disposed between the first and second roll pairs. The arrangement of the third roll pair is generally similar to that of the first roll pair, but the lower carrier of the third roll pair also is adjustable upwardly and downwardly.

When the machine is to be set for straightening a particular tube, each roll is set at a selected angle to the longitudinal centreline of the machine, the rolls of each pair are spaced a selected distance apart and the third roll pair is adjusted vertically relative to the first and second roll pairs to offset a point midway between the rolls 21 and 22 a selected distance from the straight line which joins points lying midway between the rolls of the first pair and rolls of the second pair. All of these settings are effected by power-driven adjustment means. Generally, each setting is achieved by a corresponding electic motor and the machine includes known devices for providing to the control means electrical signals representing each setting.

The control means comprises input means, for example a keyboard, by means of which the operator can feed into the control means data defining characteristics of a tube which is to be straightened. This data would include the nominal outside diameter of the tube, the wall thickness of the tube and information defining the yield strength of the tube, for example a designation of the quality of the steel of which the tube is formed and, if the tube will not be at normal temperature during straightening, then the temperature of the tube. Operation of the control means is represented in Fig. 2. The control means is provided with a programme which contains appropriate formulae for the calculation of theoretical settings of the machine appropriate to the input data defining the characteristics of tubes to be straightened. The control means computes theoretical settings and then checks a memory of the control means to see whether tube having the same characteristics has previously been straightened. If so, there are retrieved from the memory variations from the theoretical settings previously used to arrive at the actual settings of the machine used previously for straightening that tube. These variations are combined with the theoretical settings to produce recommended actual settings. Alternatively, if interrogation of the memory fails to locate information related to tube having the input characteristics, then the control means interpolates the previously recorded variations to assign variations appropriate to the tube which is to be straightened and these assigned variations are combined with the theoretical settings to produce the proposed actual settings.

The proposed actual settings are checked, to ensure that they are within the capacity of the machine. The proposed actual settings are displayed on a screen for consideration by an operator. The operator may instruct the machine to proceed with the setting of the machine in accordance with the proposed actual settings. Alternatively, the operator may instruct the control means to apply further variations to the proposed actual settings to produce new actual settings, in accordance with which the machine will then be set. The machine then operates on the tube which is to be straightened.

If more than one tube having the same characteristics is to be straightened, the operator inspects the first tube during or after straightening and, if he is not satisfied with the quality of the tube, enters into the control means further variations of the settings, using his experience to improve the settings and the quality of the straightened tube. These new settings are then stored in the memory as a record of the actual settings used. In this way, the control means learns from the experience of the operator and the information in the control means is available to be used by different operators and is available to be transferred to the control means of additional machines.

Once a variety of workpieces has been straightened by a machine having a particular specification, the accummulated record in the control means of that machine can be duplicated in the control means of a further machine having the same specification. Operators of the second machine can then benefit from the experience possessed by operators of the first machine.

Claims

1. A method of setting a machine for operating on a workpiece wherein information defining one or more characteristics of the workpiece is applied to control means of the machine, the control means computes a theoretical setting of one or more settable elements of the machine appropriate to the characteristic or characteristics applied, the control means computes an actual setting of the or each of said elements by varying the theoretical setting by an amount interpolated from or extrapolated a record of variations previously applied to theoretical settings for other workpieces and the control means provides a signal representing the computed actual setting to adjustment means which adjusts the element accordingly.

2. A method of setting a machine for operating, on successive occasions, on respective, different workpieces, wherein the machine is provided with control means comprising a memory, there is entered into the memory a set of information comprising characteristics of typical workpieces and either appropriate settings of the machine for operating on the workpieces or, for each of the workpieces, variations from settings computed according to a formula, the method defined in Claim 1 is used for setting the machine for operating on a first of said workpieces, the set of information previously applied to the memory being used as said record, the actual settings used for operating on the first workpiece are added to the record and the machine is prepared for operation on a second of the workpieces by repeating the method defined in Claim 1.

3. A method as defined in Claim 1, applied to setting a straightening machine for straightening metal tube.

4. A method according to Claim 3 wherein, after the control means has computed the actual setting of the or each said elements, the control means invites the operator to intervene and further vary the settings, prior to privision by the control means of the signal representing the actual setting to the adjustment means.

5. Apparatus comprising a machine having at least one adjustable element for operating on a workpiece and adjustment means for setting the adjustable element in a selected position and further comprising control means associated with the adjustment means to provide thereto a signal representing the selected position or representing an adjustment required to achieve the selected position, wherein the control means includes input means for receiving data defining one or more characteristics of a workpiece, computation means for computing a theoretical setting of said element according to a predetermined formula and the data defining one or more characteristics of the workpiece and a memory containing a record of variations from previously computed theoretical settings of actual settings used in operating on previous workpieces, the computation means being programmed to interpolate from the record variations appropriate to said data and to combine said variations with the computed theoretical setting to define the selected position.

6. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.