CN100378607C - A method for numerically controlled machine tool to return to reference point from any position - Google Patents

Abstract

The present invention discloses a method for enabling any position of a numerically-controlled machine tool to return to a reference point. Stop dogs with different lengths are arranged along the direction of a screw rod of the machine tool at intervals, and the lengths and the intervals of the stop dogs are prestored. When the machine tool returns to zero, the zero position of the numerically-controlled machine tool can be automatically formed according to the lengths of the stop dogs, the Z pulse position of a motor, and any position of the stop dogs arranged on the machine tool at intervals. Accordingly, when returning to the reference point, the numerically-controlled machine tool can not be limited by the zero returning direction and the zero returning position, and the zero position of the machine tool can be quickly found by the nearest stop dog at any position of the screw rod. The method improves the zero returning efficiency and the zero returning reliability, and is suitable for all numerically-controlled machine tools, such as lathing machine tools, milling machine tools and machine tools at machining centers, lathing and milling compounding machine tools, etc. The method of the present invention is particularly suitable for large numerically-controlled machine tools which are required specifically and are inconvenient to return to the reference point by the traditional method.

Description

A kind of method of numerically controlled machine tool to return to reference point from any position

Technical field

The present invention relates to a kind of method of numerically controlled machine tool to return to reference point from any position.

Background technology

The return reference point of numerically-controlled machine is the important means that ensures machining precision and safety.Usually the return reference point method of numerically-controlled machine is as follows: a return reference point block is set on the direction of return reference point, zero switching signal of returning by quick searching block, oppositely slow down again and leave block, and then at a slow speed near block, the null position of this direction is determined in the Z pulse of seeking motor.Mainly there is following shortcoming in this method: the one, before return reference point, should guarantee back that zero axle is positioned at " return reference point direction " opposition side of reference point, return reference point direction as X-axis is negative, then before the return reference point, should guarantee the forward side of X-axis current location in reference point, otherwise should manually move this axle up to satisfying this condition, influence the efficient and the security of return reference point like this; The 2nd, the inconvenient manual mobile machine tool position of some heavy duty machine tools, have only return reference point nearby this moment, sets up corresponding lathe coordinate system, as have only a return reference point block, when the distance block is far away, just can not carry out the return reference point operation.This is to guaranteeing that normal process is very disadvantageous.

For addressing the above problem, two kinds of solutions are arranged generally.The one, the motor of numerically-controlled machine adopts absolute type encoder, but because absolute type encoder is used not extensively, and use cost is higher, and at present a lot of digital control system do not support absolute type encoder, makes it to use very difficult; The 2nd, adjust the position of block according to the return reference point position of numerically-controlled machine, this will make complicated operation, and not have generality, and its application neither be very convenient.

Summary of the invention

The object of the present invention is to provide that a kind of cost is low, efficient is high, have the method for the numerically controlled machine tool to return to reference point from any position of widespread usage.

For achieving the above object, the present invention realizes by following technical measures:

The inventive method by at machine tool lead screw along two blocks that different length is installed on the direction of principal axis of return reference point at least, block is and is distributed in the lathe effective travel scope, prestore between each block length, each adjacent blockers the interval and from the reference point block farthest and the distance of lathe reference point; During return reference point, obtain the variation of return reference point switching signal and determine concrete return reference point block, analyze the reference point locations of setting up numerically-controlled machine at interval in the lathe optional position according to position and each block of each block length, Z pulse generation.Can not be subjected to the qualification of return reference point direction and position during the numerically-controlled machine return reference point like this, all can find the lathe reference point locations rapidly by hithermost block in the optional position of this leading screw.

Describedly determine that the process of concrete return reference point block is: in the return reference point process, position when writing down the return reference point switch respectively and bumping against certain block and the position when breaking away from this block, draw twice position difference, and and the length of each block compare, with the immediate block of this difference be return reference point block concrete in this time return reference point process.

The concrete quantity of described block is determined according to the return reference point shaft length of lathe.

The present invention has the following advantages compared with the prior art:

1, the application of this invention is a digital control system in open type, and its measurement, computing, decision-making are all irrelevant with the normal process operation of digital control system itself, and the some agreements that only need to understand the digital control system open interface get final product, and have advantage of wide range of application;

What 2, this invention adopted is the mode of directly measuring block length, abandon the mode of directly using expensive measurement mechanism in the absolute type encoder, have cheap characteristics, the cost that increases newly only is the cost of block, can be used as an annex of digital control system in open type (lathe), easy to install, with low cost;

3, the present invention can realize numerically controlled machine tool to return to reference point from any position, be that lathe can be at an arbitrary position, utilize the block of different length, obtain the signal and the position of return reference point, realize the purpose of lathe return reference point, thereby increase substantially return reference point efficient and reliability, numerically-controlled machine adopts this method can not be subjected to any performance constraint, can set up lathe coordinate system by the optional position return reference point, make numerically-controlled machine possess the ability of " adjusting to changed conditions ".

Description of drawings

Fig. 1 is for realizing the principle of compositionality synoptic diagram of the inventive method system;

Fig. 2 is a Control Software FB(flow block) in the inventive method;

Fig. 3 is the principle schematic of return reference point.

Embodiment

As Fig. 1, shown in Figure 3, along the block that different length is installed on the direction of principal axis of return reference point, block is as the mark of differentiating the lathe null position at machine tool lead screw, and the length of block is as distinguishing that time zero span piece foundation.Install one in addition and return zero switch, return zero switch and be equivalent to a position transducer, return zero switch and can be the signal that control system provides record position, control system is according to the corresponding position of action record of returning zero switch, and the line data of going forward side by side is handled and changed different control strategies.

On the direction of principal axis of return reference point, press spacing value P _nInstall block, spacing value P _nCan equate, also can be unequal, there is not specific requirement.Between first block starting point and last the block terminal point apart from S ₁Be exactly effective displacement of lathe, between first block terminal point and last the block starting point apart from S ₂Be exactly effective return reference point scope of lathe, the block between second block and the penult block is effective return reference point block (comprising second block and penult block) of lathe.The length of each block is L ₁～L _nNot etc., compile the sequence number of block by the unequal length value of each block, the lower limit of block length should be greater than 15mm, the upper limit does not have specific requirement, the concrete quantity of block can be determined according to zero shaft length that returns of lathe, can set several blocks when returning zero axial length more, return zero axle and can set several blocks less in short-term, as long as be distributed in the lathe effective travel scope.Determine lathe null position H (H in the expression formula), and record first block and lathe leading zero's H ₀Apart from S.With above-mentioned each block length value L _n, spacing value P _n, the prestoring of first block and lathe leading zero's apart from S, when lathe returns Z-operation, return and return in zero process after zero switch bumps against certain block, record position this moment, and moving on; When breaking away from this block, record position this moment calculates twice position difference again, and and the effective length L of return reference point scope internal stop ₂～L _N-1Compare, this difference is near that L _nValue just can determine it is which block is the reference point block in this time time zero process.Meanwhile move on behind the segment distance more oppositely at a slow speed near above-mentioned which definite block, after bumping against this block, after finding first motor Z pulse, stop, and record position H this moment _nAt this moment, can determine the null position H of lathe by following expression formula:

When lathe effective travel direction is positive dirction:

$H=H_n+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{L}_i+\underset{i=1}{\overset{n-1}{\mathrm{\Σ}}}{P}_i-S,(n\≥2)$

When lathe effective travel direction is negative direction:

$H=H_n-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{L}_i-\underset{i=1}{\overset{n-1}{\mathrm{\Σ}}}{P}_i+S,(n\≥2)$

As shown in Figure 2, above-mentioned processing procedure can realize analyzing automatically the null position of setting up numerically-controlled machine by Control Software, and Control Software comprises that data are provided with module, data acquisition, data analysis module, control module.Data are provided with module and are mainly used in the prestore distance of block length, block interval data and first block and lathe leading zero's of typing, for data analysis provides the data support; Data acquisition module mainly is the variation of obtaining back zero switching signal, is similar to the data acquisition of sensor, for record data and change control strategy provide the control benchmark.Data analysis module mainly is to carry out calculating, analyzing by above-mentioned expression formula according to the data of gathering, and provides the control result.Control module mainly is the result according to data analysis, changes and the enforcement corresponding control strategies.

Claims (2)

1. the method for a numerically controlled machine tool to return to reference point from any position, it is characterized in that: by at machine tool lead screw along two blocks that different length is installed on the direction of principal axis of return reference point at least, block is and is distributed in the lathe effective travel scope, and prestore between each block length, each adjacent blockers the interval and from the reference point block starting point farthest and the distance of lathe reference point; During return reference point, obtain the variation of return reference point switching signal and determine concrete return reference point block,, analyze the reference point locations of setting up numerically-controlled machine in the lathe optional position according to position and each block interval of each block length, motor Z pulse generation; Describedly determine that the process of concrete return reference point block is: in the return reference point process, position when writing down the return reference point switch respectively and bumping against certain block and the position when breaking away from this block, draw twice position difference, and and the length of each block compare, with the immediate block of this difference be return reference point block concrete in this time return reference point process.

2. the method for numerically controlled machine tool to return to reference point from any position according to claim 1 is characterized in that: the concrete quantity of described block is determined according to the length of the return reference point axle of lathe.

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