JPH0151300B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention is directed to a portal machine tool in which a cross rail, which is mounted so as to be able to rise and fall freely using an elevating threaded rod, is tilted by a biased load due to left and right movement of the spindle head. This invention relates to a crossrail horizontal correction device that corrects this.

<Prior art> In general, in large portal machine tools such as vertical boring and milling machines, the cross rail, which is movable in the vertical direction between the left and right columns, is operated by an elevating threaded rod installed vertically along each column. A drive shaft and a bevel gear are connected to the left and right sides of the cross beam by an elevating drive device fixed at the center of the cross beam, which is hung horizontally on the upper ends of both columns. The cross rail is raised and lowered horizontally by synchronously rotating the left and right raising and lowering threaded rods through the cross rail.

However, when the spindle head moves from the center position on the crossrail to either the left or right direction, the load borne by the left and right lifting screw rods increases or decreases, and the amount of extension of each screw changes, causing the crossrail to move downward on one side and on the opposite side. It rises and tilts. This causes inclination of the spindle and vertical deviation of the end of the spindle, resulting in problems such as a decrease in the straightness of the boring and other machining accuracy.
As a measure to reduce the inclination of the cross rail, consideration has been given to increasing the diameter of the lifting threaded rod as much as possible to reduce the amount of elongation due to load, but there are limitations due to mechanical structure constraints and cost. In addition, the left and right hydraulic pressure of the hydraulic balance cylinders installed inside or outside of both columns is used to absorb and reduce the burden of the weight of the cross rail and the spindle head on the left and right lifting threaded rods. One method is to change it according to the amount, and the other is to make the support nut on the cross rail side that is screwed to one of the lifting screw rods rotatable to eliminate the difference in the elongation of the left and right lifting screw rods due to the deviation of the spindle head. etc. are publicly known. However, with the former method, when the vertical stroke of the crossrail is large, the length of the hydraulic cylinder and the total height of the machine become too large, which limits its application, and the configuration of the variable hydraulic system that is divided into two systems, the complexity of control, and the response There are also practical difficulties such as maintaining accuracy and maintainability, and the latter nut rotation method has a power rotation mechanism built into the load holding part of the crossrail, which complicates the structure in narrow spaces and causes problems with horizontal movement of the spindle. Application is restricted due to interference and other reasons.

<Purpose> In view of the above, the present invention includes a differential gear device interposed in the rotation transmission part of the interlocking drive device for the left and right lifting screw rods provided in the center of the cross beer, and correcting rotation of the lifting screw rod on one side. In particular, the present invention provides a horizontal correction device for a crossrail which has a wide range of application, a simple structure, and a reliable effect by eliminating the difference in elongation of the elevating screw rod due to deviation of the spindle head.

<Examples> Examples of the present invention will be described below. First, the first embodiment will be explained. 1st, 5th, 6th, 7th
In the portal machine tool shown in the figure, a cross beam E is horizontally suspended between the upper ends of a pair of left and right vertical columns D and F of a bed A having a table B, and a cross beam E is installed vertically along each column D and E. A spindle head H is provided so as to be movable laterally on a cross rail C which is vertically movable across the cross rail C by the rotation of a pair of elevating screw rods 5 and 6.

A differential gear device 3 is interposed on the drive shaft 11 of the interlocking drive device 1 for both the lifting screw rods, and the lifting screw rod 6 on the differential shaft 12 side of the differential gear device 3 is independently corrected and rotated. A correction motor 4 that enables The vertical screw rod 5 is installed by changing the interlocking ratio of the left and right coupling devices.
When the interlocking drive device 1 of 6 is operated, both the lifting screw rods are made to rotate synchronously, and a cross rail C position detector 21 is installed in the interlocking drive device 1 of the lifting screw rod, and A spindle head H position detector 9 is provided in each of the drive parts, and the differential gear device 3 is operated by both detection signals from the two position detectors to rotate the differential shaft 12 side lifting screw rod 6. This structure is configured to correct the inclination of the cross rail C due to movement of the spindle head H from the center of the cross rail C in the left-right direction.

When the cross rail C is moved up and down, when the drive servo motor 2 of the interlocking drive device 1 fixed at the center of the cross beam E is operated, the sixth
A pinion 2 fitted to the motor shaft 2a as shown in the figure
2. The drive shaft 11 integrated with the drive gear 26 via the intermediate gears 23 to 25 rotates, and as shown in FIG. rotating the first planetary gear 28 and the second planetary gear 29 integrally connected to the first planetary gear 28 inside the
A differential shaft 12 disposed concentrically with the drive shaft 11 is rotated at a reduced speed together with a second sun gear 30 at the left end of the shaft.
For this purpose, the gear ratios of gears 27, 28 and 30, 29 are changed. Further, in the above, since the correction motor 4 that drives the differential gear unit 3 is stationary and servo locked, the revolving arms 33 and 34 of the double planetary gears 28 and 29 are in a fixed state. Then the fifth
As shown in the figure, the rotation of the drive shaft 11 and the differential shaft 12 is carried out via the transmission shafts 13, 14 and the bevel gear devices 17, 18 to rotate the left and right lifting threaded rods 5, 6 to raise and lower the cross rail C. The rotation ratio of the left and right bevel gear devices 17 and 18 is set to be an inverse ratio to the rotation ratio of the drive shaft 11 and the differential shaft 12 so that the elevating and lowering threaded rods rotate synchronously when the vehicle is stopped.

Next, as shown in FIGS. 1 and 7, the function of the differential gear device 3 that corrects the inclination of the cross rail C when the spindle head H is offset to the left or right from the center position of the cross rail C will be explained. When the spindle head H moves laterally from the center position to the left or right, the output signal of the position detector 9 of the spindle head H connected to the horizontal feed screw part of the spindle head H is used to detect the direction and amount of movement. , and an output signal from a position detector 21 of the crossrail C, which will be described later, the correction motor 4 is driven and rotated in the positive or negative direction, thereby rotating the pinion 32 of the differential gear device 3. As shown in Fig. 7, the drive shaft 11
A fan-shaped segment gear 35 is sandwiched between the tips of a pair of revolving arms 33 and 34, which are rotatably fitted over the differential shaft 12 which is concentric with the shaft. When the arms 33 and 34 are rotated, the pair of arms 33 and 34 also revolve, and the integral planetary gears 28 and 29, which are rotatably attached to a shaft 34a fitted inside the arms, act as a drive shaft. 11 and the second sun gear 30 of the differential shaft 12 to rotate while revolving around the sun. While the crossrail C is stopped moving up and down, the driving servo motor 2 of the interlocking drive device 1 for the lifting screw rods 5 and 6 is servo-locked and does not rotate, and as a result, the drive shaft 11 and the first sun gear 27 are also locked and rotated. do not. 2
Since the gear ratios of the sets of gears 27, 28 and 30, 29 are changed, only the differential shaft 12 rotates differentially together with the second sun gear 30, which is integrated with the shaft, and only the right lifting screw rod 6 is operated independently. As the cross rail C is rotated, the right end portion of the cross rail C moves up and down, and the inclination is corrected.

Nuts 5a and 6a in FIG. 1 are screwed together with the lifting screws 5 and 6 and supported by the cross rail C, and 7a.
is a nut supported by the spindle head H which is screwed together with the transverse feed threaded rod. In addition, in FIG. 7, P is a reducer interposed between the gear shaft 32 and the motor shaft 4a, and 51, 52, and 53 are the motor shaft 4a and the detector 1.
This is a gear for interlocking with the shaft 10a of 0.

Next, instructions and control for horizontal correction of Crossrail C will be explained. FIG. 2 shows the vertical position of the crossrail C with respect to the lifting screw rods 5 and 6, and the inclination of the crossrail C related to the left and right deviation of the spindle head H from the center of the crossrail C.
As is clear from this figure, the increase/decrease Δh2 in the elongation of the elevating screw rods 5, 6 due to the deviation of the spindle head H and the inclination θ of the crossrail C and the main shaft S are It changes in proportion to the product of the load length h of the lifting screw rods 5 and 6 related to the position and the offset L of the spindle head H portion from the center of the cross rail C to the left and right. However, the vertical height of the center portion of the crossrail C does not change even if the spindle head H shifts to the left or right. In addition, this figure shows the case where the weight load applied to the lifting screw rod is supported at one location K and L at the upper end, and in this support method, the cross rail C
As the amount of deviation of the spindle head H increases, the inclination of the crossrail C due to the deviation of the spindle head H decreases, and as it descends, the inclination increases. Therefore, even if the amount of deviation of the spindle head H remains the same, it is corrected by the vertical position of the crossrail C. The amount changes.

Although not shown in the drawings, if the lifting screw rod is provided with two weight-load supporting parts at the upper and lower ends, the inclination of the cross rail C will be maximum at the center of the lifting screw rods 5 and 6. and decreases as it approaches both support parts.

Therefore, in FIG. 2, the following equation holds true.

Δh1=k・h・W+w/2 Δh2=k・h・w/2・(±)l/L Δh=k・h・[W+w/2+w/2・(±)l/
L] tanθ=Δh2/L=k・h・w・(±)l/2L ² h: Load length of the lifting screw rod Δh1: Elongation of the left and right lifting screw rod when the spindle head H is in the center Δh2: Spindle head Increase/decrease in elongation of the left and right lifting screw rods due to deviation of H: Total elongation θ of lifting screw rods when spindle head H is uneven: Cross rail C due to deviation of spindle head H
Inclination of the spindle S l: Distance from the center of the crossrail C to the spindle head H L: Distance from the center of the crossrail C to the lifting screw rod W: Weight of the crossrail C (balance weight is subtracted) w: Spindle head Weight of H: k: Constant In Fig. 3, when the drive motor 8 rotates the feed screw 7 in response to a lateral feed command for the spindle head H and the spindle head H moves to the left or right from the center of the cross rail C, A signal corresponding to the direction and amount (±l) of deviation of the spindle head H from the center of the cross rail C is detected by a position detector 9 of the spindle head H connected to the feed screw drive unit, such as a resolver or an encoder. is output to the computing unit 37, and when the drive servo motor 2 of the interlocking drive device 1 for the vertical screws 5 and 6 is operated in response to the vertical feed command for the crossrail C, the crossrail C is moved. A load-bearing part is measured from the upper end support point (cross beam part) of the lifting screw rod to the support point of the crossrail C by a position detector 21 of the crossrail C connected to the drive unit, such as a resolver or an encoder. A signal corresponding to the length h is output to the calculator 37, and based on the output signals ±l and h from both amplifiers, the calculator 37 uses the right lifting screw rod 6 necessary to level the crossrail C. The corrected rotation amount (±2・Δh2) is calculated,
A correction instruction signal is output from the correction motor 4 drive amplifier 38 to the correction motor 4 of the differential gear device 3, and as the motor rotates, the right side lifting screw rod 6 is rotated independently, and the right side of the cross rail C is raised or lowered. The inclination of the crossrail C is then corrected with reference to the left side.

As is clear from the foregoing, Crossrail C
Horizontal correction is performed for the deviation of the spindle head H from the center of the cross rail C in the left-right direction or its increase or decrease, but when the spindle head H is in an offset position, the spindle head H remains at the same position. Even if the cross rail C moves up and down independently, the left and right lifting screw rods 6,
Since the increase/decrease Δh2 in the elongation of No. 7 changes, horizontal correction is performed accordingly.

In addition, in machines that are used with large attachments attached to the spindle head H, if the weight of the spindle head H increases significantly, the inclination of the cross rail C will increase due to the deviation, so the attachment installation confirmation signal It is also possible to add a function to output a correction command signal obtained by adding the weight increase of the spindle head H to the correction motor 4.

As described above, the horizontal correction of the inclination of the crossrail C due to the deviation of the spindle head H is achieved by corrective rotation of the right side elevating screw rod by the differential gear device 3 with the left side elevating screw rod support part of the crossrail C as a reference. This is accomplished by lifting and lowering the right side.

As mentioned above, the spindle head H is controlled by the differential gear device 3.
The inclination of the cross rail C due to the deviation of the cross rail C is corrected horizontally, but since the correction is performed based on one side (left side) of the cross rail C, the vertical position of the cross rail C after horizontal correction is based on the position of the spindle head H. A slight difference occurs depending on the offset position. In other words, when the spindle head H is offset to the left of the center of the crossrail C, the height of the crossrail C after horizontal correction is corrected to a lower position than the height of the crossrail C when the spindle head H is at the center, If the spindle head H is shifted to the right side of the center, it will be corrected to a higher position,
There is a slight difference in the height of the cross rail C when the spindle head H is at the center.

Therefore, in this embodiment, the actual value of the vertical position on the left side of the crossrail C is determined by the linear scale 15 installed along the left column D and the position detector 16 connected to the corresponding position on the left side of the crossrail C. is detected, and the output signal is fed back to the comparator 39 and compared with the set value of the vertical position of the crossrail C, and the drive motor 2 of both lifting screw rods is rotated in a corrective manner so as to eliminate the difference. , the left end of the cross rail C is corrected and positioned at an accurate vertical position regardless of the offset position of the spindle head H, and the right side lifting and lowering according to the first invention corrects the inclination of the cross rail C with this left side support part as a reference. Horizontal correction is performed by rotating the threaded rod. As a result, the crossrail C has a downward position error due to elongation due to the weight load of the crossrail C and the spindle head H hanging on the lifting screw rod, and due to deviation of the spindle head H from the center of the crossrail C in the left and right direction. The tilt and the vertical position error are corrected together, and horizontal correction is achieved at an accurate vertical position.

Normally, in this type of medium to large gantry vertical boring milling machine, etc., the tool is mounted on the spindle S and the tool is mounted on the spindle S, and the spindle is quill fed or the spindle head H
A method of vertically feeding the spindle head H using a ram is often used, and in this case, the cross rail C is used to greatly change and adjust the vertical position of the spindle head H, and is often clamped during cutting.

In addition, if the vertical feed of the cross rail C is not NC, or if the spindle head H and the copying device part are arranged on the same cross rail C, such as in a portal copy milling machine, and the cross rail C moves laterally, In the case of a method in which the probe moves up and down following the tracing of the probe, a great effect can be achieved by horizontally correcting the inclination of the cross rail C.

Furthermore, cross rail C is used for cutting feed in the vertical direction.
Crossrail C is used when NC feed of
High-precision machining is achieved by horizontal correction that is performed in conjunction with correction of the inclination and vertical position.

In addition, in the description of this embodiment, a semi-closed method is used in which a solver or the like is used to detect the horizontal deviation of the spindle head H to correct the inclination and the vertical position of the cross rail C. A closed hybrid control system is used in which a linear scale is used to detect the position for correction, but as shown in the second embodiment of FIG. 4, the linear scale 40 is also used to detect the horizontal position of the spindle head H.
Of course, it is also possible to use the linear scale 15 for detecting the vertical position of the crossrail C to correct the inclination and vertical position in a closed loop control system.

<Effects> As is clear from the above description, the present invention has a cross beam horizontally suspended between the upper ends of a pair of left and right vertical columns, and a pair of lifting screws erected along each column. In a portal type machine tool in which the spindle head is movable laterally on a cross rail that can be moved up and down by the rotation of the rod, a differential is applied to the drive shaft portion of the interlocking drive device for both lifting screw rods. A correction motor is installed with a gear device to enable independent corrective rotation of the vertical screw rod on the differential shaft side of the differential gear device, and the upper ends of the left and right vertical screw rods are connected to the rotation transmission for the interlocking drive device. A left and right coupling device is provided to connect the shaft, and the interlocking ratio of the left and right coupling devices is changed so that when the interlocking drive device for the lifting screw rod is operated, both lifting screw rods rotate synchronously, and the cross rail is a crossrail position detector that detects the length of the load-bearing part from the upper end support point of the lifting screw rod to the crossrail support point related to the vertical position; and a direction in which the spindle head is offset from the center of the crossrail. A spindle head position detector for detecting the amount is provided respectively, and the differential gear device is actuated by both detection signals from the two position detectors to rotate the differential shaft side lifting screw rod. It is configured to correct the inclination of the crossrail due to movement of the spindle head from the center of the crossrail in the left-right direction.

Therefore, according to the present invention, when the vertical feed of the cross rail is not NC, or when the spindle head and the copying device section are arranged on the same cross rail and the cross rail is moved laterally, such as in a portal copy milling machine, In cases where the cross rail moves up and down following the probe, a great effect can be achieved by horizontally correcting only the inclination of the cross rail.
That is, the present invention relates to a device that constantly corrects the inclination of the cross rail and the main spindle that occurs when the spindle head moves left and right along the cross rail in a large portal machine tool, using an elevating screw rod differential mechanism. Since it has a structure that is easy to incorporate without significantly modifying or restricting the structure or function of the machine body, it can be widely and economically applied to similar machines, and as a result, it can be used as a cross-rail elevating portal machine tool. An excellent effect can be obtained in eliminating problems such as boring and other machining precision degradation caused by the inclination of the cross rail or the main spindle when the spindle head H is offset.

Furthermore, the present invention further provides a linear scale that is erected along the column on the opposite side of the differential shaft, and a position detector that detects the actual value of the vertical position of the crossrail is connected to a position corresponding to the linear scale of the crossrail. However, the vertical position of the cross rail is corrected based on the linear scale side reference based on the detection signal from the position detector.

Therefore, according to the present invention, when NC feed of the crossrail is often used for cutting feed in the vertical direction and accuracy requirements for the vertical position are severe, horizontal correction is performed that simultaneously corrects the inclination of the crossrail and the vertical position. This also has the effect of achieving high precision machining.

[Brief explanation of drawings]

Fig. 1 is an overall front view of a portal machine tool equipped with the first embodiment of the present invention, Fig. 2 is a front view for explaining the operation of the crossrail horizontal correction device, and Fig. 3 is the same crossrail horizontal correction device. Block diagram of 4th
The figure is a block diagram of the second embodiment of the present invention, FIG. 5 is a front view of the upper part of the portal machine tool of the first embodiment of the present invention, FIG. The figure is also a sectional view of the differential gear unit. B: Table, C: Cross rail, D, F: Vertical column, E: Cross beam, H: Spindle head, 1: Interlocking drive, 3: Differential gear, 4: Correction motor, 5, 6: Lifting screw Rod, 7: Spindle head horizontal feed screw rod, 9: Spindle head position detector, 11: Drive shaft, 1
2: Differential shaft, 13, 14: Rotation transmission shaft, 15: Linear scale, 16: Position detector, 17, 18:
Bevel gear device, 21: Cross rail position detector.

Claims (1)

[Claims] 1. A cross beam is horizontally suspended between the upper ends of a pair of left and right vertical columns, and is movable up and down by the rotation of a pair of lifting screw rods installed along each column. In a portal type machine tool in which a spindle head is provided so as to be horizontally movable on a cross rail extending across, a differential gear device is interposed in a drive shaft portion of an interlocking drive device for both lifting screw rods, and the differential gear A correction motor is provided to enable independent corrective rotation of the lifting screw rod on the differential shaft side of the device, and left and right coupling devices are provided to connect the upper ends of the left and right lifting screw rods to the rotation transmission shaft for the interlocking drive device. , the interlocking ratio of the left and right coupling devices is mutually changed so that both the lifting screw rods rotate synchronously when the interlocking drive device of the lifting screw rod is operated, and the upper end of the lifting screw rod is supported in relation to the vertical position of the cross rail. a crossrail position detector that detects the length of the load-bearing part from a point to a support point of the crossrail; and a spindle head position detector that detects the direction and amount of deviation of the spindle head from the center of the crossrail. The detection signals from both position detectors actuate the differential gear device to rotate the differential shaft side lifting screw rod, thereby moving the spindle head from the center of the crossrail in the left and right direction. A crossrail horizontal correction device characterized in that it is configured to correct the inclination of the crossrail due to movement. 2. A cross beam is horizontally suspended between the upper ends of a pair of left and right vertical columns, and the cross rail is movable up and down by the rotation of a pair of vertical screw rods installed along each column. In a portal type machine tool in which a spindle head is provided so as to be movable laterally, a differential gear device is interposed in a drive shaft portion of an interlocking drive device for both lifting screw rods, and a differential gear device is provided on the differential shaft side of the differential gear device. A correction motor is provided to enable independent corrective rotation of the vertical screw rods, and left and right coupling devices are provided to connect the upper ends of the left and right vertical screw rods to the rotation transmission shaft for the interlocking drive device. The interlocking ratio is mutually changed so that both lifting screw rods rotate synchronously when the interlocking drive device for the lifting screw rod is operated, and the crossrail is supported from the upper end support point of the lifting screw rod related to the vertical position of the cross rail. A crossrail position detector for detecting the length of the load-bearing part up to a point, and a spindle head position detector for detecting the direction and amount of deviation of the spindle head from the center of the crossrail are provided, respectively. Both detection signals from the detector actuate the differential gear system and rotate the differential shaft-side lifting screw rod, which causes the spindle head to move from the center of the crossrail in the left-right direction, thereby tilting the crossrail. Further, a linear scale is installed along the column on the opposite side of the differential shaft, and a position detector for detecting the actual value of the vertical position of the cross rail is installed at a position corresponding to the linear scale of the cross rail. 1. A crossrail horizontal correction device, characterized in that the vertical position of the crossrail is corrected using a linear scale side reference based on a detection signal from the position detector.