JP2807491B2 - Numerical control unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for detecting the position of an edge of a zero-phase signal from a position detector which generates a two-phase signal and a zero-phase signal in accordance with driving of a control object. The present invention relates to a numerical control device that sets a temporary origin based on the temporary origin.

[Conventional technology]

Conventionally, with this type of device, once the origin has been set, the position of the position detector will shift slightly with time due to thermal displacement, thermal deformation, or other similar causes of the movable part. Was not considered at all.

[Problems to be solved by the invention]

For this reason, in the conventional device, the processing is performed without noticing the positional shift of the origin, and a defective processed product is generated.
Particularly, in the case of unmanned automatic continuous processing, there is a problem that a large number of defective processed products are generated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a numerical control device that does not generate a large amount of defective machining even when a position shift occurs at a once set origin.

[Means for solving the problem]

The object is to provide a control device for controlling the position of a driving device for driving a control object, a provisional origin position storage means for storing a provisional origin position of the control object, and directing the control object to the provisional origin position when desired. To determine whether the predetermined edge detection position of the zero-phase signal from the position detector is within an allowable error range with respect to the temporary origin position, and if not, at least stop machining. This is attained by providing an origin position deviation confirming means.

[Action]

The temporary origin position storage means of the control device stores the temporary origin position of the control object detected at the time of setting the origin.

Also, the origin position deviation confirmation means of the control device is provided when desired.
For example, when machining is completed, when a tool is exchanged, or when a certain time has elapsed after the start of machining, the control target is moved toward the temporary origin position. Then, it is determined whether or not the edge detection position of the zero-phase signal from the position detector is within an allowable error range with respect to the temporary origin position. At least interrupt the processing. As a result, in unmanned automatic continuous machining, a large number of defective products are not generated even when a position shift occurs at the once set origin.

If necessary, at the same time as the processing is interrupted, the machine operator is notified visually, for example, on a display, or visually, for example, by a buzzer sound.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a numerical controller according to the present invention. In FIG. 1, reference numeral 1 denotes a control object such as an XY table of a machine tool, and 2 denotes a motor and a gear for driving the control object 1. It is a driving device including a mechanism. Reference numeral 3 denotes a position detector that generates a two-phase rectangular wave signal and a zero-phase signal in accordance with the driving of the control object 1. For example, a 90-degree phase difference A-phase B-phase incremental pulse encoder, a digital scale, or the like is used. Fig. 3 shows a digital scale)
Is used.

A control device 4 controls the position of the control target 1 based on a signal from the position detector 3 and an external position command.

The numerical controller usually sets the origin before it is shipped as a product, but the controller 4 sets the position of the predetermined edge of the zero-phase signal output from the position detector 3 as the temporary origin. The origin is set based on the temporary origin.

The control device 4 includes temporary origin position storage means for storing the temporary origin position of the control target 1 detected at the time of setting the origin. Further, the control device 4 detects the predetermined edge of the zero-phase signal with the control object 1 directed to the tentative origin position when desired, for example, at the end of machining, at the time of tool change, or when a certain time has elapsed after the start of machining. Is determined until the edge detection position is within the allowable error range with respect to the tentative origin position. There is provided a means for confirming the displacement of the origin.

The control device 4 specifically includes, for example, a counter 5a, a latch circuit 5b including a D flip-flop (D-FF) circuit, a CPU 5c, a memory 5d, a D / A converter 5e, and an amplifier 5f, as shown in the figure. Is done. In this case, the memory 5d forms the main configuration of the temporary origin position storage means. Latch circuit 5b
, Together with the CPU 5c, form the main configuration of the origin position deviation checking means.

Next, the operation of the above-described device of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart, and FIG. 3 is a diagram showing the relationship between the coordinate system of the control target 1 (only one axis X is shown here for simplicity of description) and the zero-phase position S0 output from the position detector 3. FIG. 4 shows the zero-phase signal S
6 is a time chart showing a relationship between 0, a zero-phase latch signal (hereinafter, referred to as a latch signal) SL from the latch circuit 5b, and a reset signal SR of the latch circuit 5b from the CPU 5c.

Both zero-phase signal when setting the origin and checking the origin position deviation
A predetermined edge of S0, here, the right edge ER (see FIGS. 3 and 4) in the zero-phase signal waveform diagram is detected, which is performed as follows. First, the control target 1 is moved in one direction, for example, in the positive direction (right direction in the figure) while detecting the zero-phase signal S0 from the position detector 3. As appropriate
When moved, the position detector 3 generates a zero-phase signal S0, which is transmitted to the CPU 5c and the latch circuit 5b of the control device 4.
Given to. As shown in FIG. 4, the latch circuit 5b latches the left edge of the zero-phase signal S0 when detecting it, and turns on the latch signal SL. The CPU 5c outputs the reset signal SR in synchronization with the feed pulse output in the minimum movement unit, i.e., the minimum movement pulse, and monitors whether the latch signal SL is in the ON state or the OFF state to monitor its ON, OFF
The boundary of the state is determined, and the right edge ER of the zero-phase position S0 is detected with high accuracy (within the minimum movement unit). That is, the latch signal SL is turned on at the right edge ER (point K described later) of the zero-phase position S0.
The point is detected by the CPU 5c as a point one minimum movement pulse before the point where the state changes from the OFF state to the OFF state. Note that the left edge of the zero-phase signal S0 is the PR of the latch circuit (D-FF) 5b.
It is detected (as a function of the latch circuit (D-FF) 5b) when the zero-phase signal S0 is input to the (preset) terminal.

When the origin is set, the right edge ER point of the zero-phase signal S0 detected in this way is stored in the memory 5d as the temporary origin (point K) of the control target 1. Also, this temporary origin (point K)
The difference between the mechanical origin and the mechanical origin (the origin of the control target 1) is also stored in the memory 5d as the origin shift amount K0 (see step 101 in FIG. 2). Thereafter, the control target 1 is moved to the mechanical origin (0
2) (see step 102 in FIG. 2).

The above is performed before processing, and the actual numerical control processing (see steps 103 to 106 in FIG. 2) is performed after setting the origin.

Then, when desired, for example, at the end of machining of a preset one machining unit (or at the time of tool change in an automatic machining machine equipped with an automatic tool changer, here at the end of the machining), the origin position shift confirmation is performed by the latch circuit 5b. And the edge detection method of the zero-phase signal S0 by the CPU 5c. That is, first, at the end of machining, the current machine position (point P) at the end of the position command supported by a series of machining programs.
The CPU 5c performs a comparison operation between the tentative origin position (point K) and the difference (temporary origin return amount) K ′ (= P−K) (see step 107 in FIG. 2).

Next, the control object 1 is set at the K ± α point (K-α point in the illustrated example).
Point), and after positioning, at least 2α in the positive direction while detecting the ON / OFF boundary of the latch signal SL corresponding to the right edge of the zero-phase signal S0 in the drawing (temporary origin position after processing is completed). (See step 108 in FIG. 2. Note that + α and −α are allowable error values stored in the memory 5d in advance). During the movement of 2α, the CPU 5c determines whether or not there is an ON / OFF boundary of the latch signal SL (see step 109 in FIG. 2). (Step 110 in FIG. 2), and if not, processing is interrupted (see Step 111 in FIG. 2), assuming that the processing is abnormal, and the fact is notified by a buzzer sound or the like. This makes it possible to determine whether or not accurate positioning has been performed during the machining operation by a series of program position commands.

Here, the origin is set before the device is shipped, and the determination of the origin position deviation is usually performed at the installation location of the device.
M, or PROM, EPROM, EEPROM, or the like is used.

Further, although the description is omitted in the above embodiment, usually,
It also has a feedback system for speed control.

In the above embodiment, the latch circuit 5b is used, and the zero-phase signal
Although the edge position of the zero-phase signal S0 can be detected with high accuracy regardless of the size of the signal width of S0, the latch circuit 5b is omitted, and only one edge of the zero-phase signal S0 is directly detected. The position may be detected as an edge position to simplify the configuration.

〔The invention's effect〕

According to the present invention, if there is a positional shift in the origin once set, it is detected at a desired time and the processing is interrupted, so that a large number of defective products are not generated. In particular, when unattended automatic continuous machining is performed, there is an effect that occurrence of defective machining can be minimized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the apparatus of the present invention, and FIG.
FIG. 3 is a flowchart for explaining the operation of the apparatus of the present invention. FIG. 3 is a diagram showing the relationship between the coordinate system of the controlled object and the zero-phase signal output from the position detector. 6 is a time chart illustrating a relationship between a signal and a latch circuit reset signal. DESCRIPTION OF SYMBOLS 1 ... Control object, 2 ... Drive device, 3 ... Position detector, 4 ... Control device, S0 ... Zero phase signal, SL ... Latch signal, SR ... Reset signal, X ... Control object Object coordinate system,
0: Machine origin position (origin of control target), K: Temporary origin position, P: Machine current position, K0: Origin shift amount,
K ': Temporary origin return amount.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05B 19/18

Claims (1)

(57) [Claims] 1. A driving device for driving an object to be controlled, a position detector for generating a two-phase signal and a zero-phase signal in accordance with the driving of the object to be controlled, a signal from the position detector and an external signal A control device for performing position control of the control object based on a position command, wherein a position of a predetermined edge of a zero-phase signal output from the position detector is set as a temporary origin of the control object, In the numerical control device for setting the origin based on, the control device includes a temporary origin position storage unit that stores a temporary origin position of the control object, and moves the control object toward the temporary origin position when desired. And determining whether or not a predetermined edge detection position of the zero-phase signal is within an allowable error range with respect to the temporary origin position. And Numerical control apparatus characterized by comprising Te.