JP2016161493A - Inner pressure inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner pressure inspection device high in detection accuracy.SOLUTION: An inner pressure detection device includes: idling rollers respectively disposed at left and right portions of the conveyance path with a gap slightly narrower than a diameter of a can 10; two left and right rods connected to a load sensor at the other ends; two left and right load sensor connected to the other ends of the rods for converting a pressing force of the rods into electrical signals; and a signal processing device for outputting inner pressure information of the can based on the output signals of the two left and right load sensors. Further, an inner pressure inspection device may include belt conveyance means for conveying the can 10 to the vicinity of the bottom part. A head portion of the load sensor is light in weight and no vibration is generated, and this makes the detection at higher speed and higher accuracy than before.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal pressure inspection device for sealed containers, and more particularly to an internal pressure inspection device for canned beverages and the like.

  Usually, the can is in a state where the contents are sealed, and various methods have been devised to detect the sealed state. For example, for canned beverages, positive pressure canned (positive pressure canned), in which liquid nitrogen or carbon dioxide is sealed to check the sealed state, prevent deformation due to external pressure, prevent oxidation, etc. It has become. And as a typical inspection method, the following canned internal pressure inspection methods are mentioned.

  Patent Document 1 listed below discloses a canned internal pressure inspection device. This apparatus is arranged with a conveyor for placing and transporting canned foods, and facing both sides of the conveyor at a distance narrower than the diameter of the canned food, and sandwiching the can body of the transported canned food from both sides. A pair of rollers that press the cylinder inward in the diametrical direction and a detection unit that measures the reaction force of the pressed canned food are arranged at predetermined intervals along the moving direction of the conveyor. One measuring means, a second measuring means, and a drive unit for rotating the pair of rollers of the first measuring means at different peripheral speeds to rotate the can, the other roller for one roller of the first measuring means The relative angle difference between the first measuring means and the second measuring means in the radial direction is set to 90 ° ± 30 °.

JP 2004-117374 A

  In the conventional internal pressure inspection apparatus as described above, a roller equipped with a motor is connected to the load detection sensor to transport the can, the sensor head is heavy, and the detection accuracy is high when inspection is performed at high speed. There was a problem that it was low. In addition, there is a problem that the detection accuracy is lowered by the vibration of the rotating motor or roller. An object of the present invention is to solve the above-described conventional problems and to provide an internal pressure inspection device with high detection accuracy.

  The internal pressure inspection apparatus of the present invention is an internal pressure inspection apparatus for inspecting the internal pressure of a sealed container, and idle rollers that are respectively arranged on the left and right of the transport path of the sealed container at intervals slightly narrower than the diameter of the sealed container. The roller shaft is rotatably supported at one end, and the other end is connected to a load sensor and the other end is connected to the other end of the rod, and the left and right rods convert the pressing force of the rod into an electrical signal. The main feature is that it includes two load sensors and a signal processing device that outputs internal pressure information of the can based on the output signals of the two left and right load sensors.

  Further, in the above-described internal pressure inspection device, the load sensor includes four strain gauges whose resistance values change due to strain based on external pressure, and two strain gauges at the same position of the two left and right load sensors are arranged in parallel. It is connected, and a Whitstone bridge circuit is constituted by a parallel circuit of four sets of strain gauges, and the signal processing device is also characterized in that the internal pressure of the can is determined based on an output signal of the Whitstone bridge circuit. There is.

  Further, the above-described internal pressure inspection device is further characterized in that it further comprises belt conveying means for conveying the sealed container in the vicinity of the bottom. Further, the above-described internal pressure inspection apparatus is characterized in that the frame that supports the roller, the rod, and the load sensor is independent of a belt conveyor that conveys the sealed container.

The internal pressure inspection device of the present invention has the following effects.
(1) Since the head portion of the load sensor is lighter than the conventional method and vibration does not occur, detection can be performed with higher speed and higher accuracy than the conventional method.
(2) Since the belt for transporting the can is provided near the bottom of the can where the rigidity of the can is large, the influence of the belt on the internal pressure of the can is small, so that detection with higher accuracy is possible.
(3) By connecting the bridge circuits of the left and right load sensors in parallel, high-accuracy and high-speed signal processing can be performed with a simple configuration.

FIG. 1 is a plan sectional view of an internal pressure inspection apparatus according to the present invention. FIG. 2 is a vertical sectional view of the internal pressure inspection apparatus of the present invention. FIG. 3 is a circuit diagram of a load sensor portion of the internal pressure inspection apparatus of the present invention.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a plan sectional view of an internal pressure inspection apparatus according to the present invention. FIG. 2 is a vertical sectional view of the internal pressure inspection apparatus of the present invention. The internal pressure inspection apparatus of the present invention includes a frame 20 independent of the belt conveyor 11 on the upper part of the belt conveyor 11 to which the can 10 as a sealed container is conveyed. By making the frame 20 independent of the belt conveyor 11, it is possible to prevent a decrease in detection accuracy due to the vibration of the belt conveyor 11 being transmitted to the sensor.

  Two sensor units 21 are fixed to the frame 20 via two unit support members 35, 36, and 37 so as to be opposed to each other so that the position can be adjusted, and the can passes between the two sensor units 21. ing. Further, a distance sensor 40 for detecting the passage of the can 10 is fixed to the frame 20 at an upper portion of the can 10 so that the distance can be adjusted.

  The sensor unit 21 regulates the position of the can 10 so that the roller 22 that contacts the can 10, the rod 23 that connects the roller 22 and the load sensor 24, the load sensor 24, and the can 10 contact the two rollers as evenly as possible. Two guides 25 that are in contact with each other, a belt support plate 30 that supports the belt driving device that contacts the vicinity of the bottom of the can 10 and conveys the can 10 are mounted.

  The rollers 22 are arranged on the left and right sides of the conveyance path of the can 10 at intervals slightly narrower than the diameter of the can 10 so that the opposing rollers 22 come into contact with the side surface of the can 10 when the can 10 passes. The roller 22 only idles and is not driven to rotate by a motor. Therefore, the structure is simple, the size can be reduced, and the response of the sensor is improved.

  The rod 23 rotatably supports the rotating shaft of the roller 22 at one end, and the other end is connected to the load sensor 24. The rod 23 is supported by a ball spline so as to be slidable in the X-axis direction. In the connection between the roller 22 and the load sensor 24, it is necessary to eliminate backlash as much as possible. However, the structure of the sensor unit of the present invention is simple and can be reduced in size and weight.

  The load sensor 24 is, for example, a strain gauge type, and is a converter that senses a load such as a compressive force and converts it into an electric signal. The load sensor 24 is connected to the other end of the rod 23, converts the pressing force of the rod 23 into an electric signal, and outputs it. Such a load sensor is commercially available.

  Output signals output from the two left and right load sensors 24 are input to a signal processing device 50, which will be described later, and based on the average value of the outputs of each sensor 24, it is determined whether the internal pressure of the can is normal or abnormal and output.

  The rough position of the sensor unit 21 corresponding to the type of the can 10 is determined by a unit support member which will be described later. In order to finely adjust the position of the roller 22, the direction of the load sensor 24 in the can direction (X axis) Equipped with a mechanism to fine-tune the position.

  The guide 25 is a guide plate that regulates the position so that the distance between the opposing guide plates is slightly larger than the diameter of the can 10 so that the can 10 is conveyed to the center. The guide 25 is fixed to the inside of the sensor unit 21, and an opening is provided in a portion of the roller 22, and the side surface of the roller 22 slightly protrudes from the inner surface of the guide 25 that contacts the can 10.

  The belt support plate 30 is a plate that is fixed to the lower part of the sensor unit 21 and supports a belt driving device that contacts the vicinity of the bottom of the can 10 and conveys the can 10. The belt support plate 30 is provided with a pulley 32 that is engaged with a rubber belt 31 and rotated, a motor 33 that rotationally drives one pulley, and the like. The belt pressing force against the can 10 is performed by an adjusting mechanism that adjusts the tension of the belt 31 by finely adjusting the position of the pulley shaft.

  There is no pulley for supporting the belt in the lower center portion of the roller 22. The reason why the pulley is not arranged in the central portion is that the measurement of the internal pressure is affected if a large stress is applied to the can by the pulley. However, depending on the type of can, such as a thin and highly rigid can, a pulley may be added at the center.

  The distance sensor 40 uses an eddy current loss displacement meter and detects the can lid (can position) in a non-contact manner.

  The unit support members 35, 36, and 37 are each configured by combining commercially available linear motion type cross roller guides, and can be fixed at desired Y-axis and Z-axis positions corresponding to the type of the can 10 by fixing screws 38. It is configured.

  Here, an operation for changing the type of the can 10 will be described. When changing the type of the can 10, first, the fixing screw 38 is removed and the unit support members 35 and 36 are slid to widen the interval. Next, the upper position adjusting screw 42 is turned to move the support plate 43 to which the distance sensor 40 for detecting the position of the can 10 is fixed to a position corresponding to the new can type. At this time, by inserting a spacer corresponding to the height of the new can between the frame 20 and the plate on which the position adjusting screw 42 is fitted, the position can be adjusted without measuring the height. is there.

  Next, the left and right unit support members 36 are slid to narrow the interval. Then, the spacer 41 having a height corresponding to the new can type comes into contact with the support plate 43. Next, the unit support members 35 and 36 are fixed by the fixing screw 38. With the above operation, the adjustment of the width as well as the height of the can 10 is completed.

  When the height of the can 10 is the same and only the diameter is different, a spacer 41 corresponding to the can with the smallest diameter is attached, and when adjusting to a large can, the difference is placed inside the original spacer 41. Position the spacer after attaching it. Further, when it is necessary to change the position of the sensor unit 21 in the Z-axis direction, it is changed manually.

  FIG. 3 is a circuit diagram of a load sensor portion of the internal pressure inspection device of the present invention. The left and right load sensors 24A and 24B are each provided with four strain gauges, and a Whitstone bridge circuit is configured for each. Each Whitstone bridge circuit is connected in parallel and input to the differential input amplifier 51.

  The constant voltage circuit 52 of the signal processing device 50 supplies a constant voltage to the Whitstone bridge circuit. The output of the differential input amplifier 51 is the average value of the outputs of the left and right load sensors 24A and 24B, as will be described later. This average value is input to the abnormality determination circuit 53, and whether the internal pressure of the can is normal or abnormal. Is output. The can of abnormal internal pressure is removed from the belt conveyor 11 by the defective can removal mechanism 55 located behind.

  The load sensors 24A and 24B include four strain gauges whose resistance values change due to strain based on external pressure, and two strain gauges (for example, 24-1 and 24-2) at the same position of the left and right load sensors 24A and 24B. ) Are connected in parallel, and a whitstone bridge circuit is constituted by the parallel circuit of the four sets of strain gauges. The change in the resistance value of the strain gauge is output to the amplifier 51 as a voltage by the Whitstone bridge circuit.

  Here, how the change of the resistance value when the resistors of the Whitstone bridge circuit are connected in parallel affects the output will be described. If the resistance value of each strain gauge is R (in the case of no load), the combined resistance value when two resistors are connected in parallel is (R × R) / (R + R).

  If the resistance change of the strain gauge when a load is applied is Δ (R >> Δ), the resistance values are (R + Δ1) and (R + Δ2). In this case, the denominator of the combined resistance value is (R + Δ1) + (R + Δ2) = 2R + Δ1 + Δ2. Here, since R >> Δ, the denominator≈2R.

  The numerator is (R + Δ1) × (R + Δ2) = (R × R) + R (Δ1 + Δ2) + Δ1 × Δ2, and focusing on the resistance change, the second and third terms of the above equation remain. Here, since R >> Δ, the second term >> the third term, so the third term is ignored. Then, the combined resistance value≈R (Δ1 + Δ2) / 2R = (Δ1 + Δ2) / 2, which is an average value of resistance changes of the left and right load sensors 24A and 24B. In the present invention, the average value of the resistance change is detected by the Whitstone bridge circuit.

  Normally, when obtaining the average value of the outputs of two Whitstone bridge circuits, the output of each bridge circuit is received by a differential amplifier, and the output of each amplifier is input to the averaging circuit to obtain the average value. Yes. However, this method has a problem in that the accuracy and response speed cannot be increased due to variations in the characteristics of each amplifier. In the present invention, the above-described configuration enables high-precision and high-speed processing with a simple configuration.

  Although the embodiments have been disclosed above, the following modifications are also conceivable. In the embodiment, the configuration in which the belt 31 is provided in the lower portion of the roller 22 has been disclosed, but the belt 31 may be provided in both the lower portion of the roller 22 and the upper portion of the roller 22. In this way, the risk of the can falling over due to the resistance of the roller 22 is reduced, and the can 10 can be transported more reliably.

  Although the example in which the roller 22 idles has been disclosed, for example, a pulley may be attached to the shaft, and the roller 22 may be rotationally driven by a belt from a direction perpendicular to the rod 23. By driving the belt 22 from a right angle direction, the influence on the measurement of the can pressure can be reduced when the roller 22 is rotationally driven.

  Two sets of can pressure measurement units are provided upstream and downstream of the belt conveyor, and a mechanism that allows the can to rotate 90 degrees after passing the upstream and pass downstream is used to determine the can pressure based on the results of the two measurement units. You may make it determine. In this way, the grazing can be measured with higher accuracy.

  The present invention is applicable to any application for inspecting the internal pressure of a can.

DESCRIPTION OF SYMBOLS 10 ... Can 11 ... Belt conveyor 20 ... Frame 21 ... Sensor unit 22 ... Roller 23 ... Rod 24 ... Load sensor 25 ... Guide 30 ... Belt support plate 31 ... Belt 32 ... Pulley 33 ... Motor 37 ... Unit support member 38 ... Fixing screw 40 ... Distance sensor

Claims (4)

In an internal pressure inspection device that inspects the internal pressure of a sealed container,
Idle rollers that are respectively arranged on the left and right of the conveyance path of the sealed container at intervals slightly narrower than the diameter of the sealed container;
Two rods on the left and right, which rotatably support the shaft of the roller at one end and the other end connected to a load sensor;
Two left and right load sensors connected to the other end of the rod and converting the pressing force of the rod into an electrical signal;
An internal pressure inspection apparatus comprising: a signal processing device that outputs internal pressure information of the can based on output signals of the two left and right load sensors. The load sensor includes four strain gauges whose resistance values change depending on the strain based on external pressure, and two strain gauges at the same position of the two left and right load sensors are connected in parallel, respectively. A Whitstone bridge circuit is configured by the parallel circuit of the gauge,
The internal pressure inspection device according to claim 1, wherein the signal processing device determines an internal pressure of the can based on an output signal of the Whitstone bridge circuit.   The internal pressure inspection apparatus according to claim 1, further comprising a belt conveyance unit that conveys the sealed container in the vicinity of the bottom.   The internal pressure inspection apparatus according to claim 3, wherein the frame supporting the roller, the rod, and the load sensor is independent of a belt conveyor that conveys the sealed container.

Images