JPH04336929A - Balance device for portal machine tool - Google Patents

Abstract

PURPOSE:To maintain a cross rail horizontally, regardless of the shift position and turning angle of a spindle head, and provide a balance device of-improved accuracy for a portal machine tool. CONSTITUTION:A shift amount of gravity of a spindle head 23 along the direction of a cross rail 14 due to the turning motion thereof, is obtained as a positional correction amount, and this correction amount is added to the Y-axis position of the head 23 on the cross rail 14, thereby obtaining a Y-axis position based upon the gravity position of the head 23 as reference. In addition, there is provided a pressure setting means for setting balance pressure between balance cylinders 17L and 17R at both ends of the cross rail 14 on the basis of the Y-axis position so obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balance device for a portal type machine tool. Specifically, in a gate-type machine tool, a cross rail is installed on columns erected on both sides so that it can be raised and lowered vertically, and a spindle head is installed on the cross rail so that it can be moved horizontally via a saddle. It relates to a balance device that supports its own weight and the total weight on the crossrail using balance pressure such as hydraulic pressure.

0002

[Background technology] In a gate-type machine tool, a cross rail is installed on columns erected on both sides so that it can move up and down in the vertical direction, and a spindle head is installed on the cross rail so that the spindle head can be moved horizontally via a saddle. In order to reduce the load on the drive mechanism such as the screw shaft that raises and lowers the crossrail in the vertical direction, and to reduce the driving force, a balance device is installed to support the crossrail's own weight and the total weight on the crossrail using hydraulic pressure or other balancing pressure. ing.

[0003] In the conventional balance device, balance cylinders are provided at both ends of the cross rail to bias each end upward in a direction, and the balance cylinders are installed at both ends of the cross rail to move the balance cylinders to the left or right depending on the position of the spindle head moving on the cross rail. By adjusting the balance pressure of the balance cylinder, the load on the drive mechanism that raises and lowers the crossrail is adjusted to maintain the crossrail in a horizontal state regardless of the position of the spindle head.

0004

However, the conventional balance device merely adjusts the balance pressure of the balance cylinders on both sides depending on the position of the spindle head moving on the cross rail. Therefore, in gate-type machine tools configured to rotate the spindle head, that is, to rotate around the This results in a problem with accuracy.

[0005] At this time, in the case of a type in which the ram of the spindle head moves back and forth, the center of gravity position of the spindle head changes depending on the amount of movement of the ram, and also changes depending on the weight of the attachment head attached to the ram. However, there is a problem in that the position of the center of gravity of the spindle head cannot be uniquely determined only by the rotation angle of the spindle head.

[0006]The object of the present invention was to solve such conventional problems, and it is possible to maintain the cross rail in a horizontal state regardless of the movement position and rotation angle of the spindle head, thereby improving machining accuracy. The object of the present invention is to provide an improved balance device for a gate-type machine tool. In addition to the above objects, another object of the present invention is to maintain the cross rail in a horizontal state even with changes in the amount of advance and retreat of the ram and the weight of the attachment attached to the ram, thereby improving machining accuracy. Our objective is to provide a balance device for mold machine tools.

[0007]

[Means for Solving the Problems] Therefore, in the balance device for a gate-type machine tool of the present invention, cross rails are provided on columns erected on both sides so as to be able to rise and fall freely in the vertical direction, and a saddle is attached to the cross rails in a horizontal direction. The saddle is provided with a main spindle head that is rotatable about an axis perpendicular to the vertical direction of the cross rail and the moving direction of the saddle. In a balance device for a gate-type machine tool equipped with a balance cylinder that supports its own weight and the load on the cross rail by balance pressure, the amount of movement of the center of gravity in the direction of the cross rail due to the rotation of the spindle head is determined as the position correction amount, and this position correction amount is pressure setting means for setting the balance pressure of the balance cylinders at both ends based on the position of the spindle head on the cross rail;
It is characterized by

[0008] Further, the spindle head includes a ram that can move forward and backward in an axial direction perpendicular to the rotation axis, and the pressure setting means adjusts the position correction amount by taking into account the amount of movement of the ram. The balance pressure of the balance cylinders at both ends is set based on this position correction amount and the position of the spindle head on the cross rail.

Further, an attachment head is replaceably attached to the ram, and the pressure setting means is configured to adjust the position correction amount, the position of the spindle head on the cross rail, and the weight of the attachment head attached to the ram. The balance pressure of the balance cylinders at both ends is set based on the above.

0010

[Operation] When the spindle head moving on the cross rail turns, the amount of movement of the center of gravity in the direction of the cross rail due to the turning of the spindle head is determined as the position correction amount. Based on this position correction amount and the position of the spindle head on the cross rail, the balance pressure of the balance cylinders at both ends is set so that the loads applied to the drive mechanisms at both ends of the cross rail are equal. Therefore, the cross rail can be kept in a horizontal state, and as a result, processing accuracy can be improved. Here, by calculating the position correction amount by taking into account the amount of advance and retreat of the ram, and by setting the balance pressure of the balance cylinders at both ends by taking into account the weight of the attachment head attached to the ram, these fluctuations can be compensated for. The cross rail can also be kept in a horizontal state, and as a result, processing accuracy can be improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the front of the portal machine tool of this embodiment. In the same figure, 11 is the base, 12 is the base 11
This is a table that is movable in the front-rear direction (X-axis direction). Columns 13L and 13R are erected on both sides of the table 12;
A cross rail 14 is installed between 13R in the vertical direction (V-axis direction)
It is installed so that it can be raised and lowered freely. One ends of wires 15L and 15R are connected to each end of the cross rail 14, respectively. The other end of each wire 15L, 15R is connected to each column 1.
Pulleys 16L and 16 provided on the upper end surfaces of 3L and 13R
After turning R, V-axis balance cylinders 17L, 17R
is connected to. Each V-axis balance cylinder 17L, 17
R is fixed to the back surface of the columns 13L and 13R, and is hydraulically controlled to pull the cross rail 14 upward.

A saddle 21 is provided on the cross rail 14 so as to be movable in the horizontal direction (Y-axis direction). The saddle 21 has a spindle head 23 that can freely turn by a predetermined angle K in the left and right directions about an axis perpendicular to the vertical direction of the cross rail 14 and the moving direction of the saddle 21, that is, the A axis parallel to the X axis. It is set in. The spindle head 23 includes a swivel base 24 provided on the saddle 21 so as to be rotatable about the A-axis, and a swivel base 24 provided on the swivel base 24 so as to be movable forward and backward in a direction perpendicular to the A-axis (Z-axis direction). It is configured to include a ram 25 that supports a main shaft, and a Z-axis servo motor 26 that moves the ram 25 forward and backward. Note that the main axis can be moved according to the coordinate system shown in one corner of FIG. Here, the B-axis is a tilt angle control axis in the X-axis direction of the main axis, and the C-axis is an angle control axis around the Z-axis.

Various attachment heads 28 having different structures and weights are selectively attached to the tip of the ram 25. For example, various types of attachment heads 28 can be attached, from light to heavy, such as a ram end cover, an angle head, and a 5-axis head. In addition, a pair of left and right A-axis balance cylinders 3 are mounted on the saddles 21 on both sides of the spindle head 23 to support the movement of the center of gravity due to the rotation of the spindle head 23.
1L and 31R are provided respectively. Further, the swivel base 24 is provided with a Z-axis balance cylinder 32 for lifting the weight of the ram 25 and the attachment head 28 attached thereto upward. In addition,
The center of gravity G of the spindle head 23 is shifted toward the upper left in FIG. 1 by an angle δ with respect to the A axis when the ram 25 is parallel to the Z axis.

FIG. 2 shows a control device for controlling the drive of the portal machine tool. The control device includes a numerical control device (hereinafter referred to as an NC device) 41 for inputting NC data, and a sequencer 61 as a pressure setting means. The NC device 41 includes an X-axis drive system 42 that moves the table 12 in the X-axis direction, a Y-axis drive system 43 that moves the saddle 21 in the Y-axis direction, and a Y-axis drive system 43 that moves the ram 25 back and forth in the Z-axis direction. A Z-axis drive system 44 including a Z-axis servo motor 26, a V-axis drive system 45 that raises and lowers the cross rail 14 in the V-axis direction, and an A-axis drive system 46 that rotates the swivel table 24 around the A-axis are connected to each other. and position detectors 47, 48, connected thereto.
Position data Px, Py, Pz, from 49, 50, 51
Registers 52, 53, 54, 5 that update and store Pv, θ
5 and 56 are built in, respectively.

The sequencer 61 includes a servo motor (not shown) for a tool magazine, a tool exchange mechanism, etc., as well as a load current value I (while the Z-axis servo motor 26 is stopped).
A load detection circuit 67 for detecting z) and proportional electromagnetic pressure regulating valves 62, 63, 64, 65, and 66 for supplying pressure fluid to each of the balance cylinders are connected, respectively. That is, the proportional electromagnetic pressure regulating valve 62 supplies pressure fluid to the Z-axis balance cylinder 32, the proportional electromagnetic pressure regulating valve 63, 64 supplies pressure fluid to the A-axis balance cylinders 31L, 31R, and the V-axis balance. Proportional electromagnetic pressure regulating valves 65 and 66 are connected to supply pressure fluid to the cylinders 17L and 17R, respectively. Note that each of the proportional electromagnetic pressure regulating valves 62 to 66 has a structure that increases the flow rate in proportion to the supplied current.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 to 9. First, with the swivel base 24 at an angular position of 0 degrees and the ram 25 stationary, a predetermined attachment head 28 is attached to the tip of the ram 25, and then a Z-axis balance pressure correction command is given. Then, the sequencer 61 executes the Z-axis balance pressure correction process shown in the flowchart of FIG. First, step (hereinafter,
It is abbreviated as ST. ) 1, after reading the load current value I(z) of the Z-axis servo motor 26 while it is stopped from the load detection circuit 67, the process proceeds to ST2 and checks if the load current value I(z) is within the preset tolerance value α. Check if it exists. If the load current value I(z) is within the allowable value α, it means that the balance pressure in the Z-axis balance cylinder 32 is balanced against the total weight of the ram 25, attachment head 28, etc. Finish pressure adjustment in stages.

[0017] Further, in the judgment of ST2, if the load current value I(z) is not within the allowable value α, the process proceeds to ST3 and the load current value I(z) is “+” or “−” with respect to the allowable value α.
” Check. The load current value I(z) is within the allowable value α
If it is “+” for the load current value I(
The voltage output value E(z) given to the proportional solenoid pressure regulating valve 62 is increased by a certain amount β so that E(z) is within the allowable value α.
(Increase the balance pressure in the shaft balance cylinder 32 by a certain amount)
After that, proceed to ST6 and output it. Next, ST
Proceed to step 7, and return to ST1 on the condition that a certain period of time T has elapsed.

[0018] In addition, in the judgment of ST3, if the load current value I(z) is "-" with respect to the allowable value α, then ST5
The voltage output value E(z) is applied to the proportional electromagnetic pressure regulating valve 62 so that the load current value I(z) is within the allowable value α.
After decreasing by a certain amount β (reducing the balance pressure in the Z-axis balance cylinder 32 by a certain amount), the process proceeds to ST1 via ST6 and ST7. In this way, the balance pressure in the Z-axis balance cylinder 32 is balanced with the total weight of the ram 25 and the attachment head 28, and the load current value I(z) of the Z-axis servo motor 26 falls within the allowable value α. to,
That is, the above operations are automatically repeated until it is checked in ST2 that the load current value I(z) is within the allowable value α. Therefore, the balance pressure within the Z-axis balance cylinder 32 can be automatically set to a balance pressure suitable for the weight of the attachment head 28 attached to the ram 25.

Now, the NC device 41 moves the table 12, the saddle 21, the ram 25, the cross rail 14, and the swivel base 24 through the shaft drive systems 42 to 46, respectively, based on the supplied NC data. As a result, the workpiece set on the table 12 is automatically processed, and the position data Px, Py,
Pz, Pv, θ are sequential registers 52, 53, 54, 55
, 56 are updated and stored.

During this period, the sequencer 61 performs the A-axis balance pressure correction (L) shown in the flowcharts of FIGS. 4 and 5.
R) in order, and A according to the rotation angle of the swivel base 24.
After the balance pressure correction of the axis balance cylinders 31L, 31R is performed, the V-axis balance pressure correction shown in the flowchart of FIG. 6 is executed, and the balance pressure correction of the V-axis balance cylinders 17L, 17R is performed. Here, FIG. 7 is a correction diagram for the A-axis balance cylinder 31L, FIG. 8 is a correction diagram for the A-axis balance cylinder 31R, and FIG. 9 is a correction diagram for the V-axis balance cylinder 1.
It is a correction diagram for 7L and 17R.

In FIGS. 7 and 8, AA...Current rotation angle of the swivel base 24, aa...Current rotation angle of the A-axis within the correction range, a...Length of the base within the correction range, V1...Ram ( Z-axis) height of the correction output value at maximum extension, V2...ram (Z-axis) height of correction change value at maximum retraction, (ram Z-axis stroke S (z) = 75
It is 0mm. ), OFV...Offset value to the proportional solenoid pressure regulating valves 63, 64, (value for correcting the dead zone of the proportional solenoid pressure regulating valves 63, 64) LA...Correction start angle, HV...At maximum ram retraction LV... is the corrected output value when the ram is extended to the maximum.

In addition, in FIG. 9, S(y)...Y-axis stroke, UV...upper limit output value to the proportional electromagnetic pressure regulating valves 65, 66, DV...lower limit output to the proportional electromagnetic pressure regulating valves 65, 66. The value EL(v) is the output value to the proportional electromagnetic pressure regulating valve 65, and ER(v) is the output value to the proportional electromagnetic pressure regulating valve 66. Therefore, the flowcharts in FIGS. 4, 5, and 6 will be explained with reference to these figures.

First, in the A-axis balance pressure correction (L), as shown in FIG. 4, first, in step 11, it is checked whether the turning angle AA of the turning table 24 is larger than the correction start angle LA. If the turning angle AA is not larger than the correction start angle LA,
Proceeding to ST18, the offset value OFV is output to the proportional electromagnetic pressure regulating valve 63, and the process ends. If the turning angle AA is larger than the correction start angle LA, proceed to ST12 (aa×V1
)/a = correction data ■ is calculated, then the process proceeds to ST13, (aa×V2×Pz)/(a×S(z) )=correction data ■ is calculated, and then, the process proceeds to ST14, ■+■ +OF
After calculating V = total output data EL(A), ST1
Proceeding to step 5, it is checked whether the total output data EL(A) is less than or equal to the preset maximum output data ELM(A). The total output data EL(A) is the maximum output data ELM(A
) or less, proceed to ST16 and set the total output data EL(A)
If the total output data EL(A) is not less than the maximum output data ELM(A), the process proceeds to ST17, outputs the maximum output data ELM(A), and ends the process.

Next, in the A-axis balance pressure correction (R), as shown in FIG. 5, it is first checked in ST21 whether the turning angle AA of the turning table 24 is smaller than the correction start angle LA. If the turning angle AA is not smaller than the correction start angle LA,
Proceeding to ST28, the offset value OFV is output to the proportional electromagnetic flow rate adjustment valve 64, and the process ends. If the turning angle AA is smaller than the correction start angle LA, proceed to ST22 (aa×V
1) Calculate /a=correction data ■, then proceed to ST23, calculate (aa×V2×Pz)/(a×S(z))=correction data ■, then proceed to ST24, ■+ ■＋O
After calculating FV = total output data ER(A), ST
The process advances to step 25 to check whether the total output data ER(A) is less than or equal to the preset maximum output data ERM(A). The total output data ER(A) is the maximum output data ERM(
A) or less, proceed to ST26 and total output data ER(A
), and if the total output data ER(A) is not less than the maximum output data ERM(A), the process proceeds to ST27, outputs the maximum output data ERM(A), and ends the process.

Finally, in the V-axis balance pressure correction, as shown in FIG. 6, first, in ST31, the position data Py on the Y-axis is read, and then the process proceeds to ST32, where the position data Py in the Y-axis direction is calculated based on the rotation angle of the swivel table 24. The amount of movement of the center of gravity is determined as the Y-axis position correction amount Δy. In other words, the output value EL(A) to the pressure regulating valve 63 which controls the left balance cylinder 31L is subtracted from the output value ER(A) to the pressure regulating valve 64 which controls the right balance cylinder 31R, and the difference is calculated by the coefficient C. Find the Y-axis position correction amount Δy. Next, the process proceeds to ST33, where the Y-axis position correction amount Δy is added to the Y-axis position data Py to obtain Y-axis position data Py' in consideration of the movement of the center of gravity. In other words, the position data Py on the Y axis is offset by the amount of movement of the center of gravity.

[0026] Next, proceed to ST34 (UV-DV)×
After calculating Py'/S(y) +DV=■, ST35
Proceed to ① and add the Z-axis balance correction value E(z) to obtain the output value EL(v) to the proportional electromagnetic pressure regulating valve 65. Next, proceed to STST36 (UV-DV) x (S
After calculating (y)-Py')/S(y) +DV=■, the process proceeds to ST37, where the Z-axis balance correction value E(z) is added to ■, and the output value ER to the proportional electromagnetic pressure regulating valve 66 is calculated. (v
). Finally, proceed to ST38 and each output value EL (
v), ER(v) using proportional electromagnetic pressure regulating valves 65, 66
Output each to and end the process.

Therefore, according to this embodiment, the displacement of the center of gravity position of the spindle head 23 in the Y-axis direction due to the rotation of the spindle head 23 is determined as the Y-axis position correction amount Δy, and this Y-axis position correction amount Δ
y is added to the Y-axis position data Py to obtain Y-axis position data Py' based on the center of gravity of the spindle head 23, and based on this Y-axis position data Py', the left and right V-axis balance cylinders 17L are adjusted.
, 17R, the cross rail 14 can be held in a horizontal state regardless of the movement position and turning angle of the spindle head 23, and as a result, machining accuracy can be improved.

Furthermore, in determining the Y-axis position correction amount Δy, the rotation angle of the spindle head 23 is determined from the difference in balance pressure between the left and right A-axis balance cylinders 31L, 31R that balance the rotation of the spindle head 23, and this rotation angle is Since the amount of unbalance caused by
Because it utilizes the difference in balance pressure between the left and right A-axis balance cylinders 31L and 31R, which balances the turning of the
Calculations can be performed more easily and quickly than when calculating from the beginning.

In addition, the left and right A-axis balance cylinders 31L
, 31R, the spindle head 23
Since the balance pressure of the left and right A-axis balance cylinders 31L, 31R is determined by taking into account the amount of movement of the ram 25, the balance pressure of the left and right A-axis balance cylinders 31L, 31R can be determined accurately.

In addition, when determining the balance pressure of the left and right V-axis balance cylinders 17L, 17R based on the Y-axis position data Py', the weight of the attachment head 28 attached to the ram 25 is taken into account and the balance pressure of the V-axis balance cylinders 17L, 17R is determined based on the Y-axis position data Py'. Since I decided to find the balance pressure of 17R,
That is, since the balance pressure of the V-axis balance cylinders 17L and 17R is determined by accurately considering the total weight applied to the cross rail 14, it is possible to set the balance pressure accurately.

Furthermore, since the balance pressure in the Z-axis balance cylinder 32 is set according to the weight of the attachment head 28 attached to the ram 25, the weight of the attachment head 28 attached to the ram 25 can be adjusted by replacing the attachment head 28. Even if the weight changes,
The ram 25 can always be moved forward and backward with a constant driving force.

In the above embodiment, the Y-axis position correction amount Δ
To find y, subtract the output value EL(A) to the pressure regulating valve 63 that controls the left balance cylinder 31L from the output value ER(A) to the pressure regulating valve 64 that controls the right balance cylinder 31R, and calculate the difference. is divided by the coefficient C to find the Y-axis position correction amount Δy, but the amount of movement of the center of gravity of the spindle head 23 in the Y-axis direction is found from the rotation angle θ of the swivel base 24, and this is used for Y-axis position correction. The amount may be Δy.

[0033]

As described above, according to the present invention, the balance pressure of the balance cylinders provided at both ends of the cross rail is set in consideration of the movement of the center of gravity due to the rotation of the spindle head. The cross rail can be held horizontally regardless of the movement position and turning angle of the spindle head, and as a result, machining accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of a portal machine tool of the present invention.

FIG. 2 is a block diagram showing a control device that controls the drive of the portal machine tool of FIG. 1;

FIG. 3 is a flowchart showing Z-axis balance pressure correction processing.

FIG. 4 is a flowchart showing processing of A-axis balance pressure correction (L).

FIG. 5 is a flowchart showing processing of A-axis balance pressure correction (R).

FIG. 6 is a flowchart showing a V-axis balance pressure correction process.

FIG. 7 is a diagram showing a correction diagram of the A-axis balance cylinder (31L).

FIG. 8 is a diagram showing a correction diagram of the A-axis balance cylinder (31R).

FIG. 9 is a diagram showing a correction diagram of the V-axis balance cylinders (17L, 17R).

[Explanation of symbols]

13L, 13R Column 14 Cross rail 17L, 17R V-axis balance cylinder 21 Saddle 23 Spindle head 24 Swivel base 25 Ram 28 Attachment head 31L, 31R A-axis balance cylinder 32 Z-axis balance cylinder 61 Sequencer (pressure setting means)

Claims (3)

[Claims] Claim 1: A cross rail is provided on columns erected on both sides so as to be vertically movable, a saddle is provided on the cross rail so as to be movable horizontally, and a spindle is mounted on the saddle in the vertical direction of the cross rail. and a gate that is rotatable about an axis perpendicular to the direction of movement of the saddle, and that balance cylinders are provided at both ends of the cross rail to support the weight of the cross rail and the load applied to the cross rail by balance pressure. In a balance device for a mold machine tool, the amount of movement of the center of gravity in the direction of the cross rail due to the rotation of the spindle head is determined as a position correction amount, and based on this amount of position correction and the position of the spindle head on the cross rail, the amount of movement of the center of gravity in the direction of the cross rail is determined based on the amount of position correction and the position of the spindle head on the cross rail. A balance device for a gate-type machine tool, characterized in that it is provided with pressure setting means for setting the balance pressure of a balance cylinder. 2. A balance device for a portal machine tool according to claim 1, wherein the spindle head includes a ram that can freely move forward and backward in an axial direction perpendicular to the rotation axis, and the pressure setting means is , determining the position correction amount by taking into consideration the amount of advance and retreat of the ram, and setting the balance pressure of the balance cylinders at both ends based on this position correction amount and the position of the spindle head on the cross rail. A unique balance device for gate-type machine tools. 3. A balance device for a portal machine tool according to claim 2, wherein an attachment head is replaceably attached to the ram, and the pressure setting means is configured to adjust the position correction amount and the pressure on the cross rail. A balance device for a portal machine tool, characterized in that the balance pressure of the balance cylinders at both ends is set based on the position of the spindle head and the weight of an attachment head attached to the ram.