JP2607717B2 - Numerically controlled grinding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a numerically controlled grinding machine, and more particularly to a so-called direct cutting in which a sizing device is used to make a cut to a predetermined size while simultaneously performing a traverse feed and a cut feed. The present invention relates to a numerically controlled (hereinafter, referred to as NC) grinding machine capable of continuous traverse infeed grinding.

(Prior Art) In an NC grinding machine, there are a traverse intermittent cut and a traverse continuous cut as a method of grinding a processing surface of a workpiece wider than a grindstone. Therefore, the former is shown in FIG.
As shown in FIG. 2, a traverse feed in which the grindstone 20 moves in a direction following the processing surface of the workpiece 21 and a cutting feed in which the workpiece 21 is cut in the radial direction are alternately and repeatedly performed. In this case, as shown in FIG.
Since the grinding surface 22 of the workpiece 20 is only the end face of the grindstone, the cutting depth cannot be increased. On the other hand, since the grinding surface 22 moves following the processing surface of the workpiece 21, the accuracy such as cylindricity is high, and therefore it is used for finish grinding. On the other hand, the latter is a method in which traverse feed and cut feed are simultaneously performed as shown in FIG. 6 (B). In this case, as shown in FIG. 7 (B), the grinding surface 22 of the grindstone 20 during the traverse feed is composed of the grindstone end surface and the grindstone outer surface, so that the grinding efficiency is high, but the accuracy of the cylindricity is poor. Therefore, it is used for rough grinding.

For the sizing method, a sizing device that directly measures the diameter of the workpiece during grinding is used, and the slicing feed is terminated by the sizing signal from the sizing device. There is an indirect sizing method in which the position to be cut is instructed in advance, and when the position is reached, the cutting feed is terminated. The direct sizing method has high dimensional accuracy because it directly measures the workpiece diameter.

In general, when traverse grinding a workpiece having a large allowance, in consideration of efficiency and accuracy, the roughing process is often directly performed by a fixed-size traverse continuous cut, and the finishing process is often directly performed by a fixed-size traverse intermittent cut.

Hereinafter, the operation of the conventional direct-size traverse continuous incision grinding will be described. FIG. 4 is a block diagram showing the configuration of a conventional NC grinding machine that performs continuous traverse continuous incision grinding. Machining program for instructing traverse direct fixed-size continuous infeed grinding stored in program storage unit 2
The SA is transferred to the program analysis unit 3. The program analysis unit 3 analyzes the input machining program SA and outputs data SB for directly executing the fixed-size traverse continuous infeed grinding.
Create Data SB includes traverse right end position ZP, traverse left end position ZN, traverse speed T, cutting speed
_{C and the} like. The function generator 4 generates an interpolation command SD for the operation in FIG. 5 (A) with reference to the data SB, and drives the driving device 9 with the interpolation command SD. That is, when the vehicle traverses to the right, it is moved at the combined speed R of the rightward traverse speed T and the cutting speed _C. Conversely, when the vehicle traverses to the left, the combined speed L of the leftward traverse speed T and the cutting speed _C To move. The above operation is repeated until a command position described later is replaced.

By the way, what matters here is the operation when the fixed size signal SH is turned on. Generally, when the driving device 9 receives the interpolation command SD
When the grinding machine body 10 is driven based on the following, a follow-up delay occurs. Therefore, assuming that the command position of the continuous interpolation command SD is CONn, the current position of the machine detected from the grinding machine body 10 by the machine position detector 8 is APAn, and that the following delay occurs as a primary delay system, generally Equation (1) holds. Here, a K _V is a position loop gain (1 / sec).

= K _V (CONn-APAn) (1) Equation (1) indicates that the greater the feed rate, the greater the following delay, which is the difference between the command position CONn and the machine position APAn. FIG. 5 (B) is a diagram showing the relationship between the command position CONn and the current machine position value APAn near where the fixed-size signal SH is turned on. In the figure, the command position before the fixed size signal SH is turned on advances from CON1 to CON2 to. Further willing to size signal SH at that reached CON7 is turned on, but the command position CON7 are cuts to X _C, mechanical current position APA7 the influence of the follow-up delay is the position of S, actually
It is cut only to the position of X _A , but it must not be cut any further. At this time, the command position replacement unit 7 replaces the command position SC obtained by the function generation unit 4 with the machine current position SG detected by the machine position detection unit 8 in response to the turning on of the sizing signal SH, It is transferred to the function generator 4 as the position SI. In the example shown in FIG. 5B, the command position replacement unit 7 generates a command position CON8 in which the command position CON7 is replaced with the current machine position S (APA7). Or later,
The function generating unit 4 executes the traverse movement without cutting with the cutting speed C = 0 and sequentially executes CON8 → CON9 →... Until the traverse end, and ends.

(Problems to be Solved by the Invention) In the above-described conventional NC grinding machine, the command position is replaced when the fixed-size signal SH is turned on, thereby moving from CON7 to CON8 per interpolation interval time. becomes equivalent to the command feed rate, depending on the value of K _V exceeds the maximum feed speed of the driving device 9. In such a case, it is necessary to reduce the traverse speed T so as to reduce the following delay amount. However, the traverse speed T must ask one by one taking into account the position loop gain K _V and the maximum feed speed of the driving device 9, not only very troublesome, traverse than the maximum feed speed having a drive 9 There is a problem that the grinding time becomes long in order to keep the speed T low.

Also, due to the speed change caused by replacing the commanded position when the sizing signal SH is turned on,
There is a problem that the processed surface is creased.

The present invention has been made under the circumstances described above,
SUMMARY OF THE INVENTION It is an object of the present invention to effectively perform the capability of a driving device without considering the influence of a position loop gain, and to perform a direct-size traverse continuous incision grinding in which a machining surface of a workpiece is not caught. To provide an NC grinder that can

(Means for Solving the Problems) According to the present invention, it is possible to perform so-called direct sizing traverse continuous incision grinding in which slicing is performed to a predetermined size using a sizing device while simultaneously performing traverse feeding and cutting feeding.
The present invention relates to an NC grinder,
The grindstone performs a traverse feed that advances and retreats in the traverse operation line direction parallel to the workpiece axis direction and a cutting feed that advances and retreats in the workpiece radial direction at the same time relative to the workpiece, and outputs a sizing signal from the sizing means. In a numerically controlled grinding machine capable of terminating only the cut feed based on the traverse feed speed and the cut feed speed included in the machining program, a function generating means for performing interpolation and outputting as a command position, and a machine current position A traverse operation line corresponding to the current machine position based on the traverse feed speed, the cut feed speed, the command position and the current machine position in response to the input of the fixed-size signal; Command position calculating means for calculating and obtaining the command position of, and the command position in the function generating means in the command position calculating means. It is achieved by providing a command position replacing means for replacing the command position of the traverse operation line.

(Operation) In the present invention, when the commanded position is replaced by the detection of the sizing signal, the commanded position on the traverse operation line with respect to the machine current position obtained as a result of the calculation by the commanded position calculation unit instead of the machined current position. , The movement of the command position caused by the replacement of the command position occurs only by the amount of delay following the infeed speed. In general, since the cut feed speed is much lower than the traverse feed speed, the movement of the command position caused by the replacement of the command position does not exceed the maximum feed speed of the driving device. Further, by being replaced with the position on the traverse operation line, the traverse feed speed, that is, the feed speed in the traverse operation line direction does not change before and after the replacement of the command position, so that the work surface of the workpiece is not caught.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a numerically controlled grinding machine according to the present invention. In the figure, components other than a command position calculation unit 6, a command position replacement unit 7, a function generation unit 4, and a machine position detection unit 8 are the same as those in the related art, and a description thereof will be omitted. FIG. 2 is a flowchart of an operation procedure in the present invention. Hereinafter, based on the drawing, the function generating unit 4, the command position calculating unit 6, the command position replacing unit 7, and the machine position detecting unit 8 in the case of performing the continuous traverse continuous incision grinding directly.
Will be described.

When the data SB for directly executing the fixed size traverse continuous incision grinding is directly input from the program analysis unit 3, the function generation unit 4 turns off the internal flag and performs initialization (step S1). Next, it is determined whether or not the internal flag FLAG is ON (step S2). If the internal flag FLAG is OFF, it is determined that the command position is not yet replaced, and the process proceeds to step S3. It is determined that the position has been replaced, and the process proceeds to step S9. Therefore, first, when the FLAG is off, since the command position has not yet been replaced, the function of the traverse continuous cutting that moves at the combined speed of the traverse feed speed T and the cut feed speed _C is generated (step S3). Next, the command position calculation unit 6 outputs the fixed-size signal
It is determined whether or not SH is on (step S4).
If it is determined in step S4 that the sizing signal is ON, first, the command position calculation unit 6 reads the current machine position SG from the machine position detection unit 8 (step S5).
Next, the command position calculator 6 calculates a command position on the traverse operation line from the data SK transferred from the function generator 4 and the current machine position SG (step S6).

Here, the contents of the calculation executed by the command position calculation unit 6 based on FIGS. 3 (A) and (B) will be described. FIG. 3 (A) is a diagram showing a case where the processing surface is straight. In the figure, CONn is a command position obtained as a result of function interpolation by the function generator 4, and is a command position calculator 6 as data SK together with the traverse feed speed T and the cut feed speed _C.
Is forwarded to Therefore, it is assumed that the command position at the time when the sizing signal SH is turned on is CON6, and the current position of the machine at that time is S. At this time, the coordinates of the next command position CON7 when the traverse feed and the cut feed are continued are X _CON7 ,
If Z _CON7 and the coordinates of the current position S of the machine are X _APA and Z _APA ,
The coordinates of the command position CON8 on the traverse operation line are obtained by the following equations (2) and (3).

X _CON8 = X _APA ... (2) Z _CON8 = Z _CON7 ... (3) FIG. 3 (B) shows a case where the work surface of the workpiece is tapered. It intersects the workpiece axis at a taper angle A. In this case, the coordinates X _CON8 and Z _CON8 of the command position CON8 on the traverse operation line are _obtained by the following equations (4) and (5). X _CON8 and X _CON7 are diameter data.

X _CON8 = X _APA +2 (Z _CON7 −Z _APA ) tan (A)… (4) Z _CON8 = Z _CON7 …… (5) Command position X _CON8 , Z on the traverse operation line obtained as described above _CON8 is the command position replacement unit 7 as data SJ
Is forwarded to The command position replacing unit 7 reads the command positions X _CON6 and Z _CON6 generated by the function generating unit 4 as data, replaces them with X _CON8 and Z _CON8 , and transfers them to the function generating unit 4 (step S7). The function generator 4 turns on the internal flag FLAG to store that the command position has been replaced (step S8), and returns to step S2.

On the other hand, if the sizing signal has not been turned on in step S4, the function generator 4 returns to step S2 without executing steps S5 to S8. If the internal flag is turned on in step S2, the function generator 4 generates the function of the traverse feed speed T assuming the infeed speed _C = 0 (step S2).
9) Until the traverse end is reached (step S10), the process is repeatedly executed. If it is determined in step S10 that the function has been generated up to the traverse end, the continuous cut of the fixed-size traverse is directly terminated.

(Effect of the Invention) As described above, according to the numerically controlled grinding machine of the present invention, when performing the continuous tracing continuous cutting directly, the movement amount of the command position caused by the replacement of the command position is equal to the following delay amount with respect to the cutting feed speed. Only. In general, the cut feed speed is considerably smaller than the traverse feed speed, and therefore, the amount of delay in following the cut feed speed is negligible compared to the traverse feed speed, and it is necessary to substantially consider the influence of the position loop gain. It is possible to increase the traverse feed speed up to near the maximum feed speed of the drive device. Further, since the feed speed on the traverse operation line, that is, the traverse feed speed is not changed before and after the replacement of the command position, the work surface of the workpiece is not caught.

Overall, according to the numerically controlled grinding machine of the present invention, it is possible to shorten the grinding time and improve the work quality in the continuous cutting of the fixed-size traverse directly.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an NC grinding machine according to the present invention, FIG. 2 is a flowchart of an operation procedure according to the present invention, and FIG. 3 (A) is a diagram for explaining a case where a machined surface is straight. FIG. 3 (B) is a view for explaining a case where the machined surface is tapered, FIG. 4 is a block diagram showing the configuration of a conventional NC grinding machine for performing continuous traverse continuous incision grinding, and FIG. 5 ( FIGS. 6A and 6B are diagrams for explaining conventional traverse continuous incision grinding, and FIGS. 6A and 6B are diagrams illustrating traverse intermittent incision and traverse continuous incision grinding. It is a figure for explaining. DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Program storage part, 3 ... Program analysis part, 4 ... Function generation part, 5 ... Sizing device, 6
... Command position calculation unit 7, Command position replacement unit 8, Machine position detection unit 9, Driving device 10, Grinding machine body, 20
…… Whetstone, 21 …… Workpiece, 22 …… Grinding surface.

Claims (2)

(57) [Claims] 1. A traversing feed in which a grindstone advances and retreats in a traverse operation line direction parallel to a workpiece axis direction and a cutting feed in which a grinding wheel advances and retreats in a workpiece radial direction, simultaneously executing a grinding wheel. In a numerically controlled grinding machine capable of terminating only the cut feed based on the fixed size signal, a function generating means for performing interpolation based on the traverse feed rate and the cut feed rate included in the machining program and outputting as a command position, A machine position detecting means for detecting a machine current position, and a machine current position based on the traverse feed speed, the cut feed speed, the command position, and the machine current position in response to the input of the sizing signal. A command position calculating means for calculating a command position on a corresponding traverse operation line, and a command position calculating means for calculating a command position in the function generating means. Numerically controlled grinding machine, characterized in that it comprises a command position replacing means for replacing the command position of the traverse operation line in stages. 2. A command position calculating means for obtaining a command position on a traverse operation line which intersects with a workpiece axis at a taper angle when a machining surface of the workpiece has a tapered shape. Numerical control grinding machine described in 1.