CN109696128B

CN109696128B - Correction method for improving steel pipe length measurement stability

Info

Publication number: CN109696128B
Application number: CN201811539548.8A
Authority: CN
Inventors: 王超
Original assignee: Yantai Lubao Steel Pipe Co Ltd
Current assignee: Yantai Lubao Steel Pipe Co Ltd
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2020-07-10
Anticipated expiration: 2038-12-17
Also published as: CN109696128A

Abstract

The invention discloses a correction method for improving the stability of steel pipe length measurement, which is characterized in that a P L C scans a grating state in real time when the length measurement starts, state data are collected, no matter which group of grating passages are shielded, the grating state is set in the P L C, the group of gratings are kept and the states of the gratings are stored in a stack, when the grating state changes and the encoder value is cleared in the advancing process of a steel pipe, a change grating is continuously set until a length measurement oil cylinder extends out of a front limit position, the maintained grating state is taken from the stack and is uploaded to an upper computer together with the encoder value for calculation, the grating state stored in the stack in the P L C is reset when the length measurement oil cylinder retracts to the start position, although the grating state changes and the encoder value cleared and the final uploaded grating state and the encoder value may not be in the same scanning period at a critical point, the grating state is stored, the continuity of the grating change is ensured, and the error caused by the change of the critical state can be effectively corrected.

Description

Correction method for improving steel pipe length measurement stability

The technical field is as follows:

the invention relates to the technical field of measurement and control, in particular to a correction method for improving the stability of steel pipe length measurement; the method is a correction method for critical errors possibly generated when the length of the steel pipe is measured by using the grating group and the encoder in the prior art, so that the length measurement errors generated in the grating critical state are eliminated, and the stability of the length measurement of the steel pipe is improved.

Background art:

the existing grating group and encoder length measurement technology is as follows: the steel pipe length measuring equipment consists of a hydraulic cylinder with an encoder, a 23-pair grating group, a damping roller group and a control system;

in the control method (see fig. 2), the grating state is a real-time state, if the tail of the steel pipe is just stopped at the critical position of a certain group of gratings, the gratings have signal jitter and the phenomenon of induction and non-induction exists, so that random errors are generated during measurement. The same steel pipe is possibly measured accurately, and the length of just one group of gratings is possibly reduced; the control steps are as follows:

1) the length measuring oil cylinder extends out to push the measured steel pipe to operate, and meanwhile, the encoder starts to count;

2) when the grating changes in the advancing process of the steel pipe, the encoder counts and resets;

3) the full stroke of the oil cylinder sends out a stretching-out-in-place signal;

4) the P L C transmits the immediately collected grating state value and the encoder reading value to the upper computer;

5) the upper computer calculates the length of the steel tapping pipe through operation;

6) returning the length measuring oil cylinder;

7) and (6) finishing length measurement.

The method comprises the steps that a hydraulic cylinder with an encoder is pushed out from an initial position and pushes a steel pipe to advance, the encoder starts counting at the same time, when the state of a grating changes in the running process of the steel pipe, the number of the encoder is reset, counting is carried out again (as shown in figure 1), when the hydraulic cylinder is pushed to a full-stroke steel pipe and does not act any more, a P L C uploads the real-time grating state and the number of the encoder to an upper computer, length measurement calculation is carried out by the upper computer, and finally the length of the steel pipe is obtained, and the relative position of the grating is fixed, so that the distance between each grating and a reference point is known, and the length (L) = the length of the steel pipe corresponding to the farthest shielded.

The length measurement method has the disadvantages that when the tail of the steel pipe just stays at the critical position of the grating passage (the critical position causes the group of grating passages to be blocked and unblocked), the grating is blocked, the encoder signal can be cleared, and because the P L C has the own scanning period, once the encoder is cleared and the data is transmitted to the upper computer, the upper computer is not in the same scanning period, the grating signal fluctuates at the critical position, the blocked grating senses the signal, the calculation of the length of the steel pipe can use the distance of the previous group of gratings and the value of the encoder after clearing, so the steel pipe is short to be measured, and the error of the distance between a pair of gratings is generated.

The invention content is as follows:

the invention aims to overcome the defects of the prior art and provides a correction method for improving the length measurement stability of a steel pipe; the method mainly solves the problem that the existing steel pipe length measuring method is easy to generate errors in a critical state; on the basis of the existing length measurement principle, a correction method of a grating state is adopted to eliminate length measurement errors caused by the fact that the grating zero clearing encoder value and the grating state are not consistent when the value is uploaded to an upper computer in the critical state and the grating state is possibly inconsistent.

The technical scheme of the invention is as follows: a correction method for improving the length measurement stability of a steel pipe is characterized by comprising the following operation steps:

a, the length measuring oil cylinder extends out to push the measured steel pipe to operate, and meanwhile, the encoder starts to count;

b, resetting and recounting the counting of the encoder when the grating changes in the advancing process of the steel pipe;

c P L C holding the raster change and storing it;

d, sending out a stretching-out-in-place signal when the oil cylinder is in full stroke;

e P L C transmitting the grating state value and the encoder reading value to the upper computer;

f, calculating the length of the steel tapping pipe by the upper computer through operation;

g P L C, comparing whether there is difference between the grating holding state value and the real-time state value, and there is difference alarm prompt;

h, returning the length measuring oil cylinder;

i resetting the grating state;

j length measurement is finished.

The invention discloses a correction method for improving the stability of steel pipe length measurement, which adopts a correction method of a grating state to eliminate length measurement errors caused by the inconsistency of the grating state possibly generated due to the fact that the numerical value of a grating zero clearing encoder and the numerical value of the grating zero clearing encoder are not in the same scanning period when being uploaded to an upper computer under the critical state. Therefore, although the grating state changes and the encoder value is cleared and finally the grating state and the encoder value are not in the same scanning period at the critical point, the grating state is stored, so that the continuity of the grating change is ensured, the reverse change cannot be generated, and the error caused by the grating critical state change can be effectively corrected;

the method comprises the steps of scanning the grating state in real time by P L C when length measurement starts, changing the real-time data acquisition of the prior method into state data acquisition, setting in P L C no matter which group of grating passages are shielded, keeping the group of gratings and storing the states of the gratings in a stack, continuously setting a change grating when the grating state changes and clears the value of an encoder in the advancing process of a steel pipe until a length measurement oil cylinder extends out of a front limit position, calling the maintained grating state from the stack and uploading the grating state and the value of the encoder to an upper computer for calculation, and resetting the grating state stored in the stack in P L C when the length measurement oil cylinder retracts to a starting position.

Compared with the prior art, the correction method for improving the stability of the length measurement of the steel pipe has outstanding substantial characteristics and remarkable progress, 1, the correction method for keeping the change state of the set grating through P L C can effectively avoid the length measurement error caused by the inconsistency of the grating state due to the fact that the value of a grating zero clearing encoder and the scanning period of the final grating state uploading are not in the same period when the steel pipe stops at the critical position of the grating, 2, the stability of length measurement equipment is greatly improved, and the length measurement error possibly generated in the critical area is avoided.

Description of the drawings:

FIG. 1 is a schematic illustration of the principle of measuring the length of a steel pipe;

FIG. 2 is a schematic diagram of a P L C procedure of a conventional length measuring method;

FIG. 3 is a schematic diagram of a trigger command for starting length measurement according to the present invention;

FIG. 4-1 is a schematic diagram illustrating the reset control of each set of gratings in the present invention;

FIG. 4-2 is a schematic diagram of the present invention showing the resetting of the raster and storing in glyph form;

FIG. 5 is a schematic diagram of a retraction triggering instruction of the length measuring cylinder according to the present invention;

FIG. 6 is a schematic diagram of a command for resetting a previously set grating group after an oil cylinder is retracted to a position;

FIG. 7-1 is a schematic diagram of a raster real time status and hold status compare instruction of the present invention;

fig. 7-2 is a schematic diagram of the differential alarm of the present invention.

The specific implementation mode is as follows:

for a better understanding and appreciation of the invention, reference will now be made to specific embodiments thereof in which the invention is illustrated in detail; the examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.

Embodiment 1, referring to fig. 3, 4-1, 4-2, 5, 6, 7-1, and 7-2, when length measurement starts, a P L C scans a grating state in real time, and changes real-time data acquisition used in the existing method into state data acquisition adopted by the method of the present invention, that is, no matter which group of grating passages are blocked, the grating state is set in a P L C and the group of gratings is maintained and the state is stored in a stack, when the encoder value is cleared in the advancing process of a steel pipe, the change grating is continuously set until a length measurement cylinder extends to a front limit position, at this time, the maintained grating state is taken from the stack and is uploaded to an upper computer together with the encoder value for calculation, when the length measurement cylinder retracts to the start position, the grating state stored in the P L C is reset, and simultaneously, a grating real-time state and stored state comparison function is added in a control program, and when the two states are inconsistent, an alarm function is introduced to remind an operator to strengthen attention.

The control steps are as follows:

(1) the length measuring oil cylinder extends out to push the steel pipe to be measured to operate, meanwhile, an encoder starts counting (see figure 3), namely, the length measuring is started, and meanwhile, whether the grating state change exists or not is judged to be effective or not according to the fact that the oil cylinder completely extends out to the position of a sensor at the front position of the oil cylinder; if the grating change does not exist in the whole length measurement process, the length measurement is invalid, and if the grating change exists, the length measurement is valid, and the next procedure is continuously executed;

(2) when the grating changes in the advancing process of the steel pipe, the encoder counts and resets;

(3) p L C makes a holding instruction for raster change and stores the raster change (see FIGS. 4-1 and 4-2). fig. 4-1 only lists 1-3 groups of rasters, and actually all 23 groups of rasters need to write the same program instruction respectively, and the addresses are analogized in sequence, so the description is not repeated, and fig. 4-2 resets all 23 groups of rasters and stores the raster change in a word form;

(4) the full stroke of the oil cylinder sends out a stretching-out-in-place signal;

(5) the P L C transmits the maintained grating state value and the encoder reading value to an upper computer;

(6) the upper computer calculates the length of the steel tapping pipe through operation;

(7) p L C compares whether the grating holding state value and the real-time state value are different, and a difference alarm prompt (see figures 7-1 and 7-2) exists, namely, the grating holding state value and the real-time state value are compared, if the two states are inconsistent, a signal is sent to a buzzer to alarm, an operator is reminded to notice that the steel pipe is in the grating critical position and needs to pay attention to the steel pipe, and measurement errors are avoided;

(8) returning the length measuring oil cylinder (see figure 5);

(9) resetting the raster state (see fig. 3, 6);

(10) and (6) finishing length measurement.

According to the correction method for improving the steel pipe length measurement stability, although the grating state changes and the encoder value is cleared and finally the grating state and the encoder value are uploaded in different scanning periods at the critical point, the grating state is stored, so that the continuity of the grating change is ensured, the reverse change is avoided, and the error caused by the grating critical state change can be effectively corrected.

Claims

1. A correction method for improving the stability of steel pipe length measurement is characterized by comprising the following operation steps:

c P L C holding the raster change and storing it;

e P L C transmitting the grating holding state value and the encoder reading value to the upper computer;

h, returning the length measuring oil cylinder;

i resetting the grating state;

j length measurement is finished.