JP2682568B2 - Sheet thickness online measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet thickness on-line measuring device, and more particularly to a thickness measuring device for measuring the thickness of a synthetic resin sheet in real time immediately after completion of stretching.

[0002]

2. Description of the Related Art As shown in FIG. 3, a stretching device for a synthetic resin sheet (1) comprises a hopper (2) for loading resin pellets.
And a screw feeder (3) with a heater (3A),
A slit (4A) for delivering molten resin, a T-die (4) equipped with a bolt (4B) for adjusting the opening size of this slit, an air knife (5), and a peripheral speed gradually increasing toward the downstream side. Stretching rollers (6) whose speed is controlled to
(7) and (8) and a thickness detection sensor (9
A), a sheet thickness measuring device (9) including a measuring shaft (18), and a winding roller (10) are sequentially arranged from the upstream side to the downstream side.

The sheet thickness measuring device (9) is shown in FIG.
As shown in FIG. 1, an AC servomotor (12), a ball screw (13), and a horizontal beam member (1) whose lower surface is a smooth guide surface (14A) are formed above a gate-shaped frame (11).
4) and place the ball screw (1
3) A ball nut (16) screwed with the movable block (17) that slides along the guide surface (14A) of the lateral beam member (14) when the AC servomotor (12) is started.
And a sheet thickness measuring sensor fixed to the lower surface of the movable block (17), for example, a linear gauge sensor (9A)
By disposing the main body (15) of the measuring device consisting of the sheet thickness measuring sensor (9A) and a measuring shaft (18) having a smooth sheet supporting surface (18A) parallel to the traverse path of the sheet thickness measuring sensor (9A), Form a method of online measurement.

The synthetic resin pellets (19) charged into the hopper (2) are melted by being heated by the heater (3A) when being pressure-fed in the screw feeder (3),
After being sent out from the slit (4A) of the T-die (4) onto the air knife (5) as an uncured thick synthetic resin sheet (1), a plurality of stretches in which the peripheral speed gradually increases from upstream to downstream By being stretched between the rollers (6), (7) and (8), the thickness T is reduced to a preset final dimension while gradually hardening, and in this state, the take-up roller (10) is a unit of a predetermined length. Rolled up.

The thickness of the synthetic resin sheet (1) is measured by a linear gauge sensor (9A) on a measuring shaft (18) immediately after being wound on a winding roller (10) after completion of stretching, as shown in FIG. T is measured. The measured value T of the thickness of the synthetic resin sheet (1) is sent as an electric input signal to the control unit (20) of the computer connected to the sheet thickness measuring device (9), and the set thickness is set here. To
Is calculated and compared with. This calculation result is obtained by observing the measured value of the thickness T displayed on a cathode ray tube display device, for example, a CRT color display (21), which is integrated with the operation panel (21A) for adjusting the sheet thickness, and the T-die (4). Manually operate the bolt (4B) of the slit, and until the measured value T of the thickness of the synthetic resin sheet (1) becomes equal to the set thickness To, slit (4A)
The opening size of is adjusted.

[0006]

The sheet thickness measuring device (9) shown in FIGS. 3 and 4 has a thickness T of a synthetic resin sheet (1) which moves while being supported from below by a measuring shaft (18). Is measured using a linear gauge sensor (9A) traversing along the axial direction of the measuring shaft (18) in a horizontal plane orthogonal to the moving direction of the synthetic resin sheet (1). In this case, since the linear gauge sensor (9A) is traversing with reference to the guide surface (14A) of the lateral beam member (14), these surfaces (14A)
The flatness and parallelism of A) have a great influence on the measured value of the thickness T. For example, if the finishing accuracy of the guide surface (14A) is not sufficient and fine irregularities of micron order remain on the surface, the depth and height of these irregularities are added or subtracted during the comparison calculation. The sheet thickness T displayed on the color display (21) has an error. In addition, if the measurement shaft (18) has a deviation in parallelism or waviness, a similar error occurs. Therefore, even if the manual operation of the bolt (4B) is repeated, the synthetic resin sheet (1)
It becomes difficult to maintain the thickness T after stretching within the control limit of the set thickness To. Since the difference in the thickness T directly leads to the quality defect of the product, in order to prevent such inconvenience,
When manufacturing a thickness measuring device, it is necessary to select finishing processing conditions such as polishing so that the above-mentioned guide surface (14A) and sheet supporting surface (18A) have sufficient flatness and parallelism, and also to improve assembly accuracy. However, the cost increase was inevitable.

Further, conventionally, a sheet thickness measuring device as described in JP-A-56-44803 and JP-A-61-296201 has been proposed, but in the former, the sheet surface is detected. Since the method uses a light projector and a photodetector, the light from the light projector is irregularly reflected by the unevenness of the sheet surface, which makes it impossible to perform accurate measurement. In addition, in the latter device, although the linear proportional region with respect to the set distance up to the detection target of the eddy current displacement detection sensor is narrow, the linear proportional region deviates from this linear proportional region and a large amount of movement is made. There was a drawback that the sheet thickness could not be measured. An object of the present invention is to provide a traverse type sheet thickness measuring device which can solve the above-mentioned drawbacks of the conventional device.

SUMMARY OF THE INVENTION To achieve the above object, the present invention is directed to a traverse composed of an AC servomotor, a ball screw, and a sideways beam member having a smooth guide surface above a portal frame. A device is disposed below the traverse device, a ball nut screwed with the ball screw, a movable block that slides along the smooth guide surface of the lateral beam member when the AC servomotor is started, and a movable block that moves the device. A traverse configured by disposing a main body of a measuring device including a sheet thickness measuring sensor mounted on the lower surface of a block and a measuring shaft having a smooth sheet supporting surface parallel to the traverse path of the sheet thickness measuring sensor. In the sheet thickness measuring device of the mold, the measurement shuffling is performed at positions equidistant on both sides in the traverse direction of the sheet thickness measuring sensor. An eddy current type or capacitance type displacement detection sensor for detecting a change in the distance to the surface of the sheet is fixedly arranged on a movable block, and the sheet thickness is measured by an arithmetic average value of the detection values of these two sensors. The present invention provides an on-line sheet thickness measuring device characterized by correcting the sheet thickness detected by a sensor.

[0008]

[Function] An eddy current type or capacitance type displacement detection sensor that detects the change in the distance to the surface of the measurement shaft in a non-contact manner is fixed to the movable block at positions equidistant on both sides of the sheet thickness measurement sensor in the traverse direction. Since the sheet thickness detected by the sheet thickness measurement sensor is corrected by the arithmetic mean value of the detection values of the two sensors, the deviation of the surface parallelism and flatness such as the inclination or waviness of the surface of the measuring shaft is corrected. Even if there is, this can be corrected and the sheet thickness can be accurately measured. If there is a deviation in parallelism and flatness due to the finishing accuracy or assembly accuracy of the guide surface of the lateral beam member that controls the parallel movement of the movable block,
The two non-contact sensors detect the relative displacement of the measuring shaft with respect to the surface, and simultaneously correct the displacement.
In particular, since the two displacement detection sensors are fixedly arranged on the movable block, it is possible to perform accurate measurement within the linear proportional region of the above-mentioned sensors, and by the combination configuration of this and the sheet thickness measurement sensor. It is now possible to provide an accurate sheet thickness measuring device which cannot be obtained by the conventional device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of the present invention will be described with reference to FIGS. In the following description, FIG. 3 and FIG.
The same components as those of the conventional device shown in FIG. 2 are denoted by the same reference numerals, and the description of the overlapping matters will be omitted.

Thickness measuring device (2) for the synthetic resin sheet (1)
5) is an eddy current type or capacitance type displacement detection sensor (26) in a pair in parallel with the sheet thickness measurement sensor (9A) at positions equidistant on both sides in the traverse direction (L1 = L2). ) (27) facing each other so that the transverse beam member (14) and the measuring shaft (18)
A linear interpolating means for micron-order unevenness and undulations remaining on the surfaces (14A) and (18A) (enlarged illustration with reference numeral (28) in FIG. 2) is configured. In FIG. 2, a linear gauge is used as the sheet thickness measuring sensor (9A), and eddy current type displacement detection sensors (26) and (27) are provided at the left and right evenly arranged positions corresponding to the linear gauge. A linear interpolation means for unevenness and waviness is formed by supporting the measurement sensor (9A) of FIG. 2 so as to be able to move in synchronization with the measurement sensor (9A). Alternatively, an optical displacement meter (for example, a reflection photoelectric sensor) can be used. When a laser displacement meter is used as the sheet thickness measuring sensor (9A), in order to improve the linear interpolation accuracy of unevenness, an electrostatic capacitance type sensor is used instead of the eddy current type displacement detection sensor (26) (27). It is preferable to use a displacement detection sensor and to make the facing interval (L1 + L2) between both displacement detection sensors as narrow as possible.

The method of using the present invention will be described below. FIG.
2 and the inching button (12A) of the AC servomotor (12) is pressed while the synthetic resin sheet (1) is fed at a constant speed in the direction orthogonal to the paper surface, and the thickness measuring device (25) is placed on the measuring shaft (18). Position at the start position.
After this, set the traverse width with a digital switch etc.,
Press the start button (12B) of the AC servomotor (12) and rotate the ball screw (13) to move the movable block (1
7) The sheet thickness measuring device (25) is traversed along the axial direction of the measuring shaft (18). As a result, the linear gauge (9A) comes into contact with the surface of the synthetic resin sheet (1) supported on the measurement shaft (18) under the action of a predetermined pressing load, and the thickness T of the synthetic resin sheet (1) is reduced. To be measured. At this time, the eddy current type displacement detection sensors (26) and (27), which are opposed to each other on the left and right of the linear gauge (9A) with the facing distances L1 and L2, are arranged on the measurement shaft (1).
8) Along with the linear gauge (9A) along the axial direction, the seat supporting surface (18A) of the measuring shaft (18) is moved.
Heights α1 and α2 are read in real time.
The thickness of the synthetic resin sheet (1) measured by the linear gauge (9A) is measured by the computer control unit (2).
0), the thickness T of the sheet (1) itself and the sheet supporting surface (1
8A) is arithmetically processed as an addition value or a subtraction value with the height α of the undulations and unevenness remaining on the CRT color display (21) as a comparison value with the set thickness T ₀ . Therefore, the actual thickness T of the synthetic resin sheet (1)
In order to measure, the average value α of the heights α1 and α2 of the unevenness or the like read by the eddy current displacement detection sensors (26) and (27) from the measurement value of the linear gauge (9A), that is, (α1 + α2 ) / 2 must be added or subtracted. Therefore, the reading values of the linear gauge (9A) and the reading values of the displacement detection sensors (26) (27) are sent as input signals to the control section (20) of the computer, and the preset reference thickness T ₀ and the linear _value are set. Gauge (9
Before comparing the reading T ± α in (A), the above (α1 + α
2) / 2 is used as a variable to correct the thickness T of the synthetic resin sheet (1) by a linear interpolation method. As a result, in the CRT color display (21), the true thickness T of the synthetic resin sheet (1) in which the deviation in parallelism and flatness such as unevenness and waviness is corrected is compared with the reference thickness T _0. Is displayed.

[0012]

According to the present invention, even if the finishing accuracy and the assembling accuracy of the guide surface of the lateral beam member and the sheet supporting surface of the measuring shaft are low, those errors do not intervene in the measured value of the sheet thickness. It is possible to improve the measurement accuracy of the online measuring device, and thus reduce the cost of this type of device. In particular, since the two displacement detection sensors are fixedly arranged on the movable block, it is possible to perform accurate measurement within the linear proportional region of the above-mentioned sensors, and by the combination configuration of this and the sheet thickness measurement sensor. It is now possible to provide an accurate sheet thickness measuring device which cannot be obtained by the conventional device.

[Brief description of the drawings]

FIG. 1 is a front view of the device of the present invention,

FIG. 2 is an enlarged view of the main part,

FIG. 3 is an explanatory diagram of a stretching process of a synthetic resin sheet,

FIG. 4 is a front view of a conventional sheet thickness measuring device.

[Explanation of symbols]

 1 Synthetic resin sheet 9A Sheet thickness measuring sensor 25 Sheet thickness online measuring device 26, 27 Eddy current type or capacitance type displacement detection sensor

Claims (1)

(57) [Claims] 1. A traverse device including an AC servomotor, a ball screw, and a lateral beam member having a smooth guide surface is provided above the gate frame, and the ball is provided below the traverse device. A ball nut screwed with the screw, a movable block that slides along the smooth guide surface of the lateral beam member when the AC servomotor is activated, a sheet thickness measuring sensor attached to the lower surface of the movable block, In a traverse type sheet thickness measuring device configured by arranging a main body of a measuring device including a measuring shaft having a smooth sheet supporting surface parallel to a traverse path of the sheet thickness measuring sensor, Eddy currents that detect changes in the distance to the surface of the measurement shaft in a non-contact manner at positions equidistant on both sides in the traverse direction. Alternatively, a capacitance type displacement detection sensor is fixedly arranged on a movable block, and the sheet thickness detected by the sheet thickness measurement sensor is corrected by an arithmetic mean value of detection values of these two sensors. Online thickness measuring device.