JP2009281917A - Preheating device of strain gauge type sensor, material tester, and preheating method of strain gauge type sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preheating device capable of shortening a waiting time for stabilizing temperature properties of a load cell attached to a material tester, a material tester equipped with the device, and a preheating method of a strain gauge sensor. <P>SOLUTION: The preheating device 1 of the load cell has a power source circuit 11, regulators 12, switchers 13, and connectors 14. The power source circuit 11 converts an AC voltage supplied from a commercial power source into a predetermined DC voltage. The regulators 12 transform an input voltage into a predetermined voltage and output it. An output voltage of the regulators 12 is set by the switchers 13. The connectors 14 electrically connect the load cell 2 with the regulators 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a preheating technique performed before actually starting a test or measurement using a strain gauge type sensor.

A load cell that detects a test force with a plurality of bridge-connected strain gauges is known as a conventional technique (for example, Patent Document 1).
JP-A-8-247863

  When using a load cell, it is necessary to stabilize the load cell attached to the testing machine for a while in order to make the temperature of a plurality of strain gauges connected by bridge connection the same. For this reason, when the load cell has to be replaced frequently, there is a problem that the waiting time after the load cell is attached becomes long.

  A preheating apparatus according to the present invention is a preheating apparatus used together with a material testing machine using a strain gauge sensor, and applies the same voltage or current to the strain gauge sensor as in the actual use state of the strain gauge sensor. The sensor drive means to supply is provided.

  According to the present invention, while performing a test or measurement with a certain strain gauge type sensor, the temperature characteristics can be stabilized by preheating the other strain gauge type sensor. It can be used to shorten the waiting time for starting a test or measurement.

  In the embodiment described below, a case will be described in which a load cell in which strain gauges of two to a multiple of 2 are bridge-connected is used as a strain gauge type sensor.

  A load cell preheating apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. This preheating apparatus 1 is used together with a material testing machine using a strain gauge type sensor. Prior to the use of the strain gauge sensor in the material test, a current is supplied to the strain gauge sensor to warm the strain sensor. FIG. 1 is a block diagram for explaining the configuration of a preheating device 1 for a load cell. The preheating device 1 includes a power supply circuit 11, an output voltage control regulator 12, a changeover switch 13, and a connector 14. The power supply circuit 11 is a circuit that converts an AC voltage supplied from a commercial power supply into a predetermined DC voltage. The regulator 12 is a device that converts an input direct current or alternating current voltage into a predetermined output voltage and outputs the voltage. In the case of a load cell driven by an alternating current, the power supply circuit 11 converts it into a predetermined alternating current so that the alternating current is input to the regulator 12, and an alternating current having a predetermined voltage is output. Good.

  The changeover switch 13 sets the output voltage of the regulator 12 by a user operation. The connector 14 is fitted with the connector 22 of the cable unit CU to electrically connect the load cell 2 to the regulator 12.

  When the load cell 2 is connected to the preheating device 1, the same voltage as that attached to a material testing machine (see FIG. 4) described in detail later is supplied to the load cell 2. As a result, since the same current as in the actual use state flows through the load cell 2, the temperature characteristics of the load cell 2 can be stabilized before the test is started.

  The load cell 2 is a sensor in which 2 to 2 multiples, particularly 2 to 6 strain gauges, are bridge-connected. The load cell 2 has a connector 24B for connecting to the preheating device 1 via the cable unit CU. As will be described in detail later (see FIG. 3), the cable unit CU includes a connector 22, a cable 23, and a connector 24A.

  The preheating device 1 includes a plurality of connectors 14, and a regulator 12 and a changeover switch 13 are provided for each of the plurality of connectors 14. Thereby, the several load cell 2 from which the voltage supplied when it attaches to a material testing machine differs can be attached to the preheating apparatus 1 simultaneously.

  FIG. 2 is a view for explaining the appearance of the preheating device 1. Four units are arranged in parallel with the changeover switch 13, the connector 14, and the status display lamp 15 as one unit.

  The status display lamp 15 notifies the user of voltage supply to the load cell 2 and completion of stabilization of temperature characteristics of the load cell 2. When the load cell 2 is connected to the preheating device 1 and a specified voltage is supplied to the load cell 2, the status display lamp 15 changes from being turned off to being turned on in red. When a specified voltage is supplied to the load cell 2 for a predetermined time, the lighting color of the status display lamp 15 changes from red to green in order to notify that the temperature characteristic of the load cell 2 has been stabilized.

  The load cell 2 to which a specified voltage is supplied is placed on the upper surface 1 a of the preheating device 1. In order to reduce the influence of outside air and further stabilize the temperature characteristics of the load cell 2, a lid 16 that covers the upper surface 1 a of the preheating device 1 is provided.

  FIG. 3 is an explanatory diagram showing the overall configuration of the cable unit CU. The cable unit CU includes a connector 22 for connecting to the preheating device 1 and a connector 24A for connecting to the load cell 2. The connector 22 for connecting to the preheating device 1 is configured as a part of the connector unit 52. The connector unit 52 includes a board 54 directly connected to the connector 22. On the substrate 54, a memory circuit 56 and resistors 58A and 58B are mounted. There are various types of characteristics of the load cell 2 depending on the application, and even the same product name has different electrical characteristics. Even if the product names are exactly the same, there are differences in temperature characteristics due to the manufacturing process or assembly process. Therefore, the storage contents of the memory circuit 56 mounted on the substrate 54 and the resistance values of the resistors 58A and 58B are set to contents suitable for the specific characteristics of the load cell 21.

  For the load cell 2, a memory circuit 56 that stores a model name (indicating the type and capacity), a manufacturing number, and the like, and resistors 58A and 58B for replacing the maximum distortion of the load cell 2 with resistance values are required. The load cell 2 and the cable unit CU are always used as a pair. Actually, the load cell 2 and the cable unit CU are delivered to the user as a pair. When the repair is completed, the load cell 2 and the cable unit CU are delivered to the user as a pair.

Next, the usage method of the preheating apparatus 1 is demonstrated.
(1) The changeover switch 13 is operated to set the voltage supplied to the load cell 2 to the voltage supplied when the load cell 2 is attached to the material testing machine.
(2) The connector 22 of the cable unit CU connected to the load cell 2 is fitted into the connector 14 of the preheating device 1, and the load cell 2 is placed on the upper surface 1 a of the preheating device 1.
(3) After confirming that the status display lamp 15 has changed from red to green, remove the load cell 2 from the preheating device 1.
(4) Immediately attach the load cell 2 to the material testing machine. Since the temperature characteristics of the load cell 2 are already stabilized by preheating, the test can be started immediately after the preparation for the material test is completed.

The preheating apparatus according to the above embodiment has the following operational effects.
(1) The same voltage as the actual use state of the load cell 2 is supplied to the load cell 2. Thereby, after attaching the load cell 2 after completion of preheating to the material testing machine, it is possible to eliminate the waiting time for stabilizing the temperature characteristics.

(2) A changeover switch 13 for switching the voltage supplied to the load cell 2 is provided for each unit. Thereby, the various load cells used for a material test can be preheated simultaneously.

(3) A plurality of load cells 2 can be connected to the preheating device 1, and the voltage supplied to each load cell 2 can be changed. Thereby, the load cell 2 from which the voltage supplied when it attaches to a material testing machine can be attached at once, and the efficiency of the test performed by replacing the load cell 2 can be improved.

(4) Since the state display lamp 15 for notifying that the temperature characteristics of the load cell 2 are stabilized is provided, the user who performs the material test can accurately grasp when the load cell can be replaced.

The material testing machine of the above embodiment can be modified as follows.
(1) The voltage supplied to the load cell 2 is not limited to the voltage supplied when it is attached to the material testing machine as long as the temperature of the strain gauge built in the load cell 2 increases. This is because the load cell 2 is stabilized after the strain gauge is warmed after being attached to the material testing machine, and the waiting time can be shortened if the warming time can be shortened.

(2) As shown in FIG. 4, the material testing machine 3 may be provided with a preheating device 31. The preheating device 31 is connected to the control panel 44 of the material testing machine 3 via a cable 46. While the load cell 32 is attached to the material testing machine 3 and the test is performed, the load cell 2 to be used next in the material testing machine 3 can be preheated. Thereby, the temperature characteristic of the load cell 2 can be stabilized in the same state as the case where it is attached to the material testing machine 3. The preheating device 31 is connected to the load cell 2 during preheating via the cable unit CU.

(3) When a specified voltage is supplied to the load cell 2 over a predetermined time, the user is notified that the temperature characteristics of the load cell 2 have stabilized. However, the resistance value of the strain gauge included in the load cell 2 may be measured, and when the resistance value is stabilized, the user may be notified that the temperature characteristic of the load cell 2 has been stabilized. By doing in this way, it can detect reliably that the load cell 2 was stabilized.

(4) The voltage supplied to the load cell 2 was determined by the user's changeover switch operation. However, the preheating device 1 may automatically set the voltage. In order to perform this automatic setting, by reading out the product name and serial number recorded in the memory circuit 56 (see FIG. 3) on the material testing machine side, a prescribed voltage can be set by a control circuit (not shown). . As a result, it is possible to prevent an erroneous voltage from being supplied to the load cell 2 due to a user's erroneous operation. Also, a weight measuring device is provided on the upper surface 1a of the preheating device 1 to measure the weight of the load cell 2, or the external appearance of the load cell 2 is imaged and recognized, and based on the measurement result or the recognition result. Thus, the preheating device 2 may determine the voltage.

(5) The sensor preheated by the preheating device 1 is not limited to a load cell as long as it is a sensor using a strain gauge. For example, the preheating device 1 may be used to stabilize the temperature characteristics of an extensometer or a displacement meter.

(6) The number of connectors 14 that supply voltage to the preheating load cell 2 is plural (four), but may be one.

(7) In the embodiment described so far, the connector 14 is provided in the preheating device, and the cable unit CU and the load cell 2 are connected to the connector 14. However, a connector (not shown) may be provided in the control panel 44 (see FIG. 4) of the material testing machine 3, and the cable unit CU and the load cell 2 may be connected to the connector.

(8) In the embodiments described so far, the specified voltage is supplied to the load cell 2. However, depending on the usage form of the strain gauge type sensor, it may be configured to supply a specified current. In this case, a constant current circuit is used instead of the regulator 12 of FIG.

  It is also possible to combine one or a plurality of embodiments and modifications. It is possible to combine the modified examples in any way.

  The above description is merely an example, and the present invention is not limited to the above embodiment.

1 is a block diagram illustrating a preheating device for a load cell according to an embodiment of the present invention. It is a figure for demonstrating the external appearance of a preheating apparatus. It is explanatory drawing which shows the whole structure of a cable unit. It is a figure for demonstrating the material testing machine provided with the preheating apparatus.

Explanation of symbols

1,31 Preheating device 2,32 Load cell 3 Material testing machine 11 Power supply circuit 12 Regulator 13 Changeover switch 14, 22, 24A, 24B, 33 Connector 15 Status display lamp 16 Lid 21 Load cell body CU Cable unit

Claims (12)

A preheating device for use with a material testing machine using a strain gauge sensor,
A preheating apparatus comprising: a sensor driving unit that supplies the same voltage or current as the actual use state of the strain gauge sensor to the strain gauge sensor. The preheating device according to claim 1, wherein
A preheating apparatus using a load cell in which strain gauges of two or a multiple of 2 are bridge-connected as the strain gauge type sensor. The preheating device according to claim 1, wherein
An extensometer or displacement meter provided with at least one strain gauge is used as the strain gauge sensor. The preheating device according to claim 1, wherein
The preheating apparatus, wherein the sensor driving means includes switching means for switching a voltage or a current supplied to the strain gauge type sensor. The preheating apparatus according to any one of claims 1 to 4,
The sensor driving means simultaneously supplies a sensor driving voltage or a sensor driving current suitable for each sensor to a plurality of types of strain gauge sensors. The preheating device according to any one of claims 1 to 5,
It further comprises timer means for detecting that the same voltage or current as in actual use is supplied to the strain gauge sensor over a predetermined time, and the temperature characteristics of the strain sensor are based on the output from the timer means. A preheating device characterized in that it is determined to be stable. The preheating device according to any one of claims 1 to 5,
After supplying the same voltage or current as the actual use state to the strain gauge type sensor, the sensor further comprises a detection means for detecting that the change in resistance value of the strain gauge type sensor is stable, and outputs to the output from the detection means. And determining whether the temperature characteristic of the strain sensor is stable based on the preheating device. The preheating device according to claim 6 or 7,
A preheating apparatus further comprising an informing means for informing that the temperature characteristic of the strain sensor is stabilized.   A material testing machine comprising the preheating device according to any one of claims 1 to 8.   A strain gauge sensor used in a material testing machine is supplied with the same voltage or current as in the actual use state of the strain gauge sensor while another strain gauge sensor is used in the material testing machine. A preheating method for a strain gauge sensor. In the preheating method of the strain gauge type sensor according to claim 10,
A strain gage sensor preheating method using a load cell in which strain gages of two to a multiple of 2 are bridge-connected as the strain gage sensor. In the preheating method of the strain gauge type sensor according to claim 10,
An extensometer or a displacement meter provided with at least one strain gauge is used as the strain gauge sensor. A preheating method for a strain gauge sensor.

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