JP2001062672A - Numerical control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten machining time by providing a time constant computing means for obtaining an acceleration/deceleration time constant corresponding to the capacity of a servo motor from the computed deviation of tool arrangement and the turning direction of a tool magazine when the tool magazine starts turning and starts decelerating. SOLUTION: A magazine tool weight balance computing part 13 computes tool weight load data in a magazine turning direction of tools housed in each pot from tool number data and weight distribution data MOD corresponding to each pot on the basis of a reference pot number POT and the tool weight distribution data MOD, and obtains tool weight load data MOK of all the pots from the sum total. A function of the tool load data MOK and an acceleration/ deceleration time constant of the magazine is predetermined, and the tool weight load data MOK of all the pots is applied to the function. An optimum acceleration/deceleration time constant RVP in the case of accelerating/ decelerating from the present magazine position is thereby obtained by a computing part 14 and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical controller for controlling a machine tool.

[0002]

2. Description of the Related Art When a tool is stored in a tool magazine of a machine tool, the tools are stored in adjacent pots in an order called by a machining program in order to reduce non-cutting time. In this case, depending on the order in which the tools are used, the weight of the tools stored on the tool magazine may be unbalanced, and a load exceeding the capacity of the motor may be applied when the tool magazine is accelerated or decelerated.

[0003] This assumes a maximum loaded tool weight when selecting a servomotor for driving a tool magazine.
When the tool magazine turns in this state, the load due to the tool weight of the pot moving vertically may be offset by the load due to the tool weight of the opposing pot, and may be smaller than the total tool weight. On the other hand, when a relatively heavy tool is arranged unevenly, the load due to the tool weight is all added to the acceleration / deceleration load of the servomotor depending on the position of the tool magazine.

In order to avoid this, when the tools are stored in the tool magazine in consideration of the overall weight balance, the processing time may be increased.

In order to fundamentally solve these problems, an acceleration / deceleration time constant is set to be larger than usual or a servo motor having a large capacity is selected in consideration of an imbalance of tool weight which fluctuates depending on use conditions. Needed.

[0006]

However, the conventional numerical control device has a motor for driving the tool magazine when the tool magazine is accelerated or decelerated due to an imbalance in the tool weight due to a biased arrangement of the tools stored in the tool magazine. When a load exceeding the capacity is applied, it is necessary to increase the acceleration / deceleration time constant or to select a large capacity servomotor. If the acceleration / deceleration time constant is increased, there is a problem that, when there is no imbalance in tool weight, the machining time is prolonged without using the servomotor, even though the servomotor has sufficient capacity.

[0007] When a large-capacity servomotor is selected, there is a problem that it is expensive and power consumption increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. It is an object of the present invention to effectively utilize the ability of a servomotor for driving a tool magazine and suppress an increase in power consumption. It is another object of the present invention to provide a control device capable of shortening the machining time and further capable of coping with a tool magazine having a complicated shape as the number of tools used increases.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a numerical control device for a machine tool provided with a tool magazine driven by a servomotor, and an object of the present invention is to reduce the bias in the arrangement of tools stored in the tool magazine. Deviation calculation means for calculating, and time constant calculation for obtaining an acceleration / deceleration time constant corresponding to the capability of the servomotor from the calculated tool arrangement deviation and the turning direction of the tool magazine at the start of turning and deceleration of the tool magazine. Means for controlling the positioning of the tool magazine in accordance with the determined acceleration / deceleration time constant.

The object of the present invention is further characterized in that the bias calculating means inputs and stores the weight data of the tool stored in each pot, and determines the position of each pot from the current position data of the tool magazine. Means for determining the weight balance of the tools stored in the tool magazine based on the weight data of the tools stored in the respective pots and the position of the pots. When calculating the bias of the tool arrangement stored in the tool magazine from the tool weight, the angle data between the moving direction and the weight direction of the pot when turning the tool magazine is stored for each pot position. The load in the turning direction of each pot is obtained from the angle data and the weight data of the tool stored in each pot, and the load is stored in the tool magazine from the sum of the loads. That the deviation of the tool arrangement that is calculated as weight relative to the turning direction of the tool magazine, is more effectively achieved.

Further, according to the present invention, when a tool having a relatively small difference in weight is used, the presence or absence of the tool is used as a means for calculating the deviation of the tool arrangement stored in the tool magazine. This eliminates the need to input data, and makes it possible to easily perform optimal positioning. On the other hand, when a tool having a large difference in weight is used, as means for calculating the bias of the tool placement stored in the tool magazine, means for calculating the bias of the tool placement based on the tool weight to perform optimal positioning. Provided.

Further, the present invention calculates the deviation of the tool arrangement stored in the tool magazine from the presence or absence of a tool and the angle data between the moving direction of the pot and the direction of gravity when turning the tool magazine, or the tool weight. It is possible to cope with a tool magazine having a complicated shape.

[0013]

According to the numerical controller having the above-mentioned means, a large-capacity servomotor can be used even when the tool is stored in consideration of the reduction of the machining time and the tool weight becomes unbalanced. The operation of the tool magazine can be performed without performing.

FIG. 1 is a block diagram showing an embodiment of a numerical controller according to the present invention. The magazine control unit 1 outputs a magazine target position command COM to the magazine position command remaining distance calculation unit 2 according to a tool change command. The magazine position command remaining distance calculation unit 2 calculates the remaining distance DIS to the target position from the difference between the current magazine position POS and the magazine target position command COM. The magazine deceleration distance calculation unit 3 calculates the acceleration / deceleration time R calculated by the magazine acceleration / deceleration time calculation unit 14.
From the PV and the current feed speed, a distance SDD required for stopping the magazine is obtained. The magazine position command calculation determination unit 4
It is determined whether the current magazine operation state is accelerating operation, constant speed operation, or deceleration operation, and is controlled by the magazine position command acceleration / deceleration calculation unit 5 and the magazine position command constant speed calculation unit 6 according to the operation condition. The movement amount per cycle SRD is output. The magazine position command unit 7 is configured to execute the previous position command CON ′
Is added to the movement amount SRD per control cycle to obtain and output the magazine position command CON. The magazine motor control unit 8 has a current command value TQ corresponding to the magazine position command CON.
M is obtained, and the magazine drive motor 9 is driven. The magazine motor position detector 11 is a part of the magazine motor position detector 1.
The current position data PO of the magazine is obtained from the position detection data ED that changes with the rotation of the magazine drive motor 9 from 0.
S is obtained and fed back to the magazine position command remaining distance calculation unit 2. Data (hereinafter, referred to as tool weight distribution data) MOD obtained based on angle data between the moving direction of the pot and the direction of gravity at the time of turning the magazine is obtained for each pot position, and the magazine pot tool weight distribution data storage unit 15 is obtained. Is stored in advance. The magazine position determination unit 12 obtains the pot number POT of the reference pot position for associating the tool weight distribution data MOD of each pot according to the magazine shape with the weight data of each tool from the current position data POS of the magazine. The magazine tool weight balance calculation unit 13 associates each pot number with the tool weight distribution data MOD based on the reference pot number POT and the tool weight distribution data MOD, and generates tool number data or a tool corresponding to each pot. The tool weight load data in the turning direction of the magazine of the tool stored in each pot is calculated from the weight data and the weight distribution data MOD, and the tool weight load data MOK of all the pots is obtained from the sum of the tool weight load data. Magazine acceleration / deceleration time calculation unit 1
4 is to determine the acceleration time constant if the magazine is currently stopped, and to determine the deceleration time constant if the magazine is accelerating or operating at a constant speed.
A function of K and the acceleration / deceleration time constant of the magazine is given in advance.
, An optimum acceleration / deceleration time constant RPV for accelerating and decelerating from the current magazine position is obtained and output. Acceleration / deceleration of the magazine shall end during the movement of the magazine by one or two pots. Since the fluctuation of the tool weight balance during acceleration and deceleration can be ignored, once acceleration / deceleration operation is started, There is no change in the time constant. However, in consideration of the case where deceleration is started before shifting to the constant speed operation, the deceleration time constant is always calculated even during the acceleration operation.

FIG. 2 is a schematic diagram showing a tool magazine of the numerical controller according to the present invention. Each pot is assigned a unique pot number in the counterclockwise direction from No. 1 to the maximum number n of pots. Also, an arbitrary pot is set as a reference pot, and the pots are assigned to the pot positions from No. 1 to the maximum pot number n for convenience in the counterclockwise direction from the reference pot position. The correspondence between the pot number and the pot position changes as the magazine is turned.

FIG. 4A is a schematic diagram showing an example of the weight distribution data stored in the magazine pot tool weight distribution data storage unit 15. The tool weight distribution data is stored corresponding to the pot position number. The tool weight distribution data is obtained by the cosine of the angle between the gravity direction and the reference turning direction as shown in FIG. "1" when the gravity direction and the reference turning direction are the same direction as in the pot position A in FIG. 2, "0" when going straight as in the pot position C in FIG. It is obtained by the cosine of the angle between the turning direction. However, when the cosine obtained as in the pot position D in FIG. 2 is opposite to the reference turning direction, the weight distribution data is set to a negative value. FIG. 4B is a schematic diagram showing an example of the tool number data and the tool weight data. The tool number and tool weight data of the tool stored for the pot number are input and stored.

The magazine tool weight balance calculating unit 13 obtains the current pot numbers of the respective pot positions from the pot numbers POT of the reference pot positions obtained by the magazine position determining unit 12 and associates them with each other. To obtain tool weight load data for each pot.

“Tool weight load data of each pot” = “weight distribution data” × “tool weight data” [Equation 1] The above calculation is performed for all pots, and the sum of the calculation results is based on the tool weight. The load MOK 'is generated in the turning direction. When the load MOK ′ is a positive value, it is possible to reach the command speed in a shorter time during the turning acceleration in the reference turning direction than in the no-load state. On the other hand, when decelerating from turning in the reference turning direction, it is necessary to lengthen the deceleration time until stopping as compared with the no-load state. Therefore, when the turning direction is the same as the reference turning direction, the all-pot load data MOK has the same value as the load MOK ', and when the turning direction is opposite to the reference turning direction, the load MOK' is set to "-1". Multiplied value.

FIG. 5 is a graph showing an example of a function of the magazine acceleration / deceleration time calculation section 14 for obtaining the acceleration / deceleration time from all the pot tool weight load data MOK.
If the absolute value of the tool weight load data MOK is within a certain range, the acceleration / deceleration time constant is set to a constant value because the influence on the servomotor is small due to the ratio with the load of the magazine drive system. When the tool weight load data MOK becomes larger than the load of the drive system of the magazine, the acceleration operation of the magazine turning becomes assisted by the tool weight load,
Acceleration can be performed with a smaller time constant than in the no-load state. Conversely, when the deceleration operation is performed, the shape is hindered by the tool weight load, and the deceleration can be performed only with a larger time constant than in the no-load state. Therefore, the relationship between the tool weight load data MOK and the acceleration / deceleration time is represented by the function shown in the graph of FIG.

FIG. 6 is a block diagram showing a conventional technique. In the related art, since the time constant is not changed due to the bias of the tool arrangement, the time constant stored in the magazine acceleration / deceleration time storage unit 16 is a fixed value.

[0021]

As described above, according to the present invention, the bias of the arrangement of the tools stored in the tool magazine is calculated, and the calculated bias of the tool and the turning direction of the tool magazine are matched to the capacity of the servomotor. The acceleration / deceleration time constant is determined, and the positioning of the tool magazine is controlled in accordance with the determined acceleration / deceleration time constant, so that the tool weight can be maintained and the ability of the servo motor that drives the tool magazine can be used effectively, thus consuming It is possible to provide a numerical control device capable of suppressing an increase in electric power and shortening a processing time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a numerical controller according to the present invention.

FIG. 2 is a schematic diagram of a tool magazine.

FIG. 3 is an explanatory diagram of how to obtain weight distribution data.

FIG. 4A is a schematic diagram illustrating an example of magazine pot tool weight distribution data, and FIG. 4B is a schematic diagram illustrating an example of tool number data and tool weight data. .

FIG. 5 is a graph showing an example of a function for obtaining an acceleration / deceleration time from all pot load data.

FIG. 6 is a block diagram showing a conventional numerical control device.

[Explanation of symbols]

 1 Magazine control unit 2 Magazine position command remaining distance calculation unit 3 Magazine deceleration distance calculation unit 4 Magazine position command calculation / determination unit 5 Magazine position command acceleration / deceleration calculation unit 6 Magazine position command constant speed calculation unit 7 Magazine position command unit 8 Magazine motor Control unit 9 Magazine drive motor 10 Magazine motor position detector 11 Magazine motor position detection unit 12 Magazine position determination unit 13 Magazine tool weight balance determination unit 14 Magazine acceleration / deceleration time calculation unit 15 Magazine pot tool weight distribution data storage unit 16 Magazine acceleration / deceleration Time storage unit

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[Procedure amendment]

[Submission date] August 31, 1999 (1999.8.3)
1)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

Claims (2)

[Claims] In a numerical control device for a machine tool having a tool magazine driven by a servomotor, a bias calculating means for calculating a bias of an arrangement of tools stored in the tool magazine; At the start of deceleration, the time constant calculating means for obtaining an acceleration / deceleration time constant corresponding to the capability of the servo motor from the calculated bias of the arrangement of the tools and the turning direction of the tool magazine, and according to the obtained acceleration / deceleration time constant, A numerical control device for controlling positioning of a tool magazine. 2. The method according to claim 1, wherein said bias calculating means includes means for inputting and storing weight data of a tool stored in each pot, means for determining a position of each pot based on current position data of a tool magazine, Means for determining the weight balance of the tools stored in the tool magazine from the weight data of the tools to be stored and the pot position, calculating the bias of the tool arrangement stored in the tool magazine from the tool weight, and When calculating the bias of the tool arrangement stored in the tool from the tool weight, the angle data between the direction of movement of the pot and the direction of gravity at the time of turning the tool magazine is stored for each pot position, and the angle data and each pot The load in the turning direction of each pot is obtained from the stored weight data of the tool and the deviation of the tool arrangement stored in the tool magazine is calculated from the sum of the loads. The numerical controller according to claim 1, wherein the numerical value is calculated as a weight with respect to a turning direction of the vehicle.