RU2085830C1 - Device measuring length of moving material - Google Patents

Abstract

FIELD: measurement of length of rolled as materials on rejection-measurement machines. SUBSTANCE: ferromagnetic tape of measuring elements has shape of inverted trapezium, is placed on two guiding rollers with collars. Lower smaller base of tape has power contact with magnet which length is less than interaxial distance between guiding rollers. Distance between upper and lower sections of tape exceeds three diameters of guiding rollers. EFFECT: increased measurement accuracy. 3 dwg

Description

 The invention relates to mechanical engineering for light industry and can be used in machines for rejection and measuring the length of various rolled materials.

 A device for measuring the length of non-magnetic materials (ed. St. USSR N 449233, class G 01 B 7/04, 1971), containing a measuring element made in the form of an endless ferromagnetic tape with holes, a transporting body, a photoelectric converter connected to the meter lengths and clamping device in the form of a magnet mounted on the outside of the measuring element.

 The disadvantage of this device is the insufficiently high accuracy of measuring the length, since the measuring element is strictly oriented in the direction of supply of the fabric and does not take into account the natural bias of the material when it moves along the table or screen, which is especially typical for non-rigid roll materials.

 The purpose of the invention is to increase the accuracy of measuring the length of a moving material.

 The goal is achieved in that the ferromagnetic tape has the shape of an inverted trapezoid, the upper larger base of which is located on two guide rollers with flanges, and the lower smaller base under the influence of a magnetic field is in force contact with the magnet, the length of which in the direction of material supply is less than the center distance between the guides rollers, and the distance between the upper and lower sections of the tape is more than three diameters of the guide rollers.

 The proposed set of features allows the upper portion of the ferromagnetic tape to move relative to the guide rollers oriented in the direction of supply of the material (i.e., in the direction of counting the length), and the lower portion of the tape to move together with the material, tracking its actual direction of movement, taking into account the skew relative to the table or screen.

The trapezoidal shape of the tape contributes to its constant tension under the influence of a magnetic field, which allows the length to be counted both in the forward and reverse directions of material movement. The shorter magnet length compared to the center distance between the guide rollers makes it possible to maintain the trapezoidal shape of the magnetic tape at different thicknesses of the measured material. Since the distance between the upper and lower sections of the ferromagnetic tape is more than three diameters of the guide rollers, the ferromagnetic tape, due to its low bending stiffness, can freely move from one section of the motion path to another at significant angles of material misalignment (up to 15 ^o ).

 In addition, these features allow you to measure the length of materials of various thicknesses without reconfiguring the device, since with the stated size ratio, the device maintains its operability automatically for a wide range of thicknesses of the measured materials.

 In FIG. 1 shows a kinematic diagram of a device; in FIG. 2 diagram of the relative positioning of the main elements of the device; in FIG. 3 diagram of the reference length of the moving material during its movement with a bias.

 The device comprises a measuring element made in the form of an endless ferromagnetic tape 1 with holes; a transporting body in the form of transporting shafts 2; a photoelectric converter including a illuminator 3, a photodiode 4, an amplifier 5, a pulse shaper 6, a pulse counter 7, and a digital indicator of readings of a measured length 8; a clamping device in the form of a magnet 9 mounted on the outside of the measuring element.

 The ferromagnetic tape 1 has the shape of an inverted trapezoid, the upper larger base of which is located on two guide rollers 10 and 11 with flanges, and the lower smaller base under the influence of a magnetic field is in force contact with magnet 9. The distance between the upper and lower sections of the tape is more than three diameters of the guides rollers 10 and 11, between which is installed a screen-shutter 12.

 The device is mounted on a traverse 13 mounted on a table 14, in the groove of which a magnet 9 is fixed at the table surface, the length of which in the material supply direction is less than the center distance between the rollers 10 and 11.

 The transporting shafts 2 receive movement from an electric motor 15, through a worm gear 16 and a V-belt drive 17.

 The device operates as follows.

 The processing material 18 is pulled from the drive 19 through the table 14 by the transporting shafts 2. Under the influence of the magnetic field created by the magnet 9, the ferromagnetic tape 1 is pressed with its lower portion to the material 18, is in tension on the rollers 10, 11 and has the shape of an inverted trapezoid. In the process of movement of the tape 1, its lower section goes to the upper one, which moves along the guide rollers 10 and 11, mounted oriented along the table in the direction of material supply. The photoelectric Converter through the slit of the screen-obturator 12 captures the pulses and recounts their number in length, which is indicated on the digital indicator 8.

 If the material moves along the table with a bias, then the lower portion of the ferromagnetic tape 1, due to its low bending stiffness, moves with the material in the same direction, tracking its trajectory. In this case, the number of pulses read by the photoelectric converter will correspond to the actual length of the material stretched through the table 14.

To explain the process of counting the length, we consider the circuit shown in FIG. 3. When measuring a piece of material of length L ₀ you can write that
L ₀ n • l ₀ ,
where n is the number of pulses;
l _{0 the} distance between the holes of the tape.

If the material moves on the table with a bias at an angle α, then its actual length will be greater than the measured L, since without taking into account the bias, the counter will indicate the length
L n • l,
where l is the distance between the holes of the tape in the direction of skew.

Расчеты показывают, что при α 5^o относительная погрешность измерения составит d 0,43% что выше допустимой ГОСТ.Since l = l _o • cosα, then L = n • l _o • cosα.
The absolute measurement error will be equal to:
Δ = L _o -L = nl _o (1-cosα).
Relative measurement error

Calculations show that at α 5 ^{o the} relative measurement error will be d 0.43%, which is higher than the permissible GOST.

 The use of the device will eliminate this measurement error by tracking the direction of movement of the material.

Claims (1)

 A device for measuring the length of a moving material, comprising a measuring element made in the form of an endless ferromagnetic tape with holes, a conveying body, a photoelectric converter connected to a length counter, and a clamping device in the form of a magnet mounted on the outside of the measuring element, characterized in that it is ferromagnetic the tape has the shape of an inverted trapezoid, the upper larger base of which is located on two guide rollers with shoulders, and the lower smaller base s under the action of a magnetic field force is in contact with a magnet, whose length in the conveying direction of the material is less than the axle distance between the guide rollers, the distance between the upper and lower portions of the tape more than three diameters of the guide rollers.

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