JP2009276070A - Material testing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the main power supply of a material testing machine body has to be once cut off before a load cell is replaced on the way of a material test and the main power supply closed again after another load cell and a connection cable are connected. <P>SOLUTION: A voltage of 3.3 V is applied to the power supply line connected to a digital input/output port. The consumed current of a memory circuit 6 is about several mA while the digital input/output port maximally supplies a current of 24 mA per line, so that a sufficient power supply capacity is provided as the power supply of the memory circuit 6. After the power supply line of a memory circuit 9 is set to 3.3 V, stored data is read through the signal line of the memory circuit 6. Thereafter, the power supply line and the signal line are entirely held to 0 V. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for attaching and detaching a detector used for testing a specimen and a material testing machine main body.

It is necessary to attach a load cell having characteristics suitable for the specimen as a step before performing the material test of the specimen. Also, when replacing the load cell in the middle of a material test, the main power source of the material testing machine main body is once cut off, and after connecting a new load cell and connection cable, the main power source is turned on again. .
On the other hand, many hot-swappable systems based on so-called hot-swapping are known (for example, Patent Document 1).
JP 2000-267951 A

  However, in order to perform so-called hot-swap using the load cell that has been used conventionally, a special connector in which the power contact terminal of the connector for the connection cable is longer than the signal contact terminal must be used. Conventional dedicated cables cannot be used as they are. In other words, if the conventional dedicated cable is attached or detached while the main power supply of the material testing machine is turned on, there is a problem that the memory IC mounted inside the connector of the dedicated cable is damaged.

The present invention is mounted in the cable unit in a material testing machine for inputting a detector output signal corresponding to a test force applied to the specimen or a displacement generated in the specimen through the cable unit. A digital input / output port for supplying drive power to the active circuit; and a first port control means for supplying the drive power from the digital input / output port only during a period in which the active circuit is in a predetermined operation state; During a period when the active circuit is not in the predetermined operation state, a second port control means for holding the power supply line and the signal line of the active circuit at a predetermined potential is provided.
Here, the digital input / output port, the first port control means, and the second port control means can be configured using a programmable gate array.
In addition, a memory circuit can be included as an active circuit mounted in the cable unit, and the output signal of the detector can be calibrated based on the stored contents read from the memory circuit during a predetermined access period.
The cable unit is mounted with a passive circuit in addition to the active circuit, and the passive element included in the passive circuit and the memory read out from the memory circuit included in the active element during a predetermined access period Based on the combination with the content, the output signal from the detector can be calibrated.
Further, a coupling detection circuit for detecting that the cable unit is connected to the material testing machine main body is provided, and the first port control means is responsive to a connection confirmation signal sent from the coupling detection circuit. Drive power is supplied to the circuit.
The first port control means may supply power to the active circuit in response to a calibration instruction given from outside.
Further, an instrumentation amplifier gain adjusting means for amplifying an output signal from the detector based on the storage content read from the active circuit during a predetermined access period and the passive element included in the passive circuit. It is possible to take a configuration provided.
Further, by using the notification means, it is possible to notify the prohibition of the removal of the cable unit during the period in which the active circuit is in a predetermined operation state.

  According to the present invention, the driving power is supplied from the digital input / output port only during a predetermined operation period to the active circuit mounted in the cable unit, and during the other period, the power line of the active circuit and Since the signal line is held at a predetermined potential, the detector and the cable unit can be attached and detached while the main power supply of the material testing machine is turned on. Moreover, the conventionally used cable unit can be used as it is without any changes.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing the overall configuration of a material testing machine to which the present invention is applied. A load cell LC is connected to the material testing machine main body MTM via a cable unit CU. The cable unit CU incorporates a memory circuit 6 and resistance elements 8A and 8B, which will be described in detail later, in order to perform electrical calibration of the load cell LC. The material testing machine main body MTM includes a connector CN1 for connecting the cable unit CU.

  The cable unit CU includes a connector CN2 for connecting to the material testing machine main body MTM and a connector CN3 for connecting to the load cell LC. A connector CN2 for connecting to the material testing machine main body MTM is configured as a part of the connector unit 2. The connector unit 2 includes a substrate 4 directly connected to the connector CN2.

  On the substrate 4, a memory circuit 6 and resistors 8A and 8B are mounted. There are various types of characteristics of the load cell LC 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 their characteristics due to the manufacturing process or assembly process. Therefore, the storage contents of the memory circuit 6 mounted on the substrate 4 and the resistance values of the resistors 8A and 8B are set to contents suitable for the specific characteristics of the load cell LC.

  Calibration specific data for performing electrical calibration of the load cell LC, a model name (indicating the type and capacity), a memory circuit 6 storing a manufacturing number, and a resistor for replacing the maximum strain of the load cell with a resistance value Since the devices 8A and 8B are required, the load cell LC and the cable unit CU are always used as a pair. Actually, the load cell LC and the cable unit CU are delivered to the user as a pair. When the repair is completed, the load cell LC and the cable unit CU are delivered to the user as a pair.

  FIG. 2 is a circuit diagram showing an electrical connection mode of the material tester main body MTM, the cable unit CU, and the load cell LC.

  The material testing machine main body MTM includes a digital circuit 10 and an analog circuit 12. In the present embodiment, the digital circuit 10 is configured using an FPGA (Field Programmable Gate Array). Further, a main power supply 14 and a main power switch 16 are provided. As the digital circuit 10, FIG. 2 shows only a digital I / O circuit having a plurality of input / output ports and a coupling detection circuit 18. The coupling detection circuit 18 determines whether or not the cable unit CU is connected to the material testing machine main body MTM by constantly monitoring the loopback signal.

  The cable unit CU includes a short circuit for returning a loopback signal transmitted from the material tester main body MTM to the material tester main body MTM in addition to the memory circuit 6 and the resistors 8A and 8B described in FIG. . The power supply line and the signal line of the memory circuit 6 are connected to the digital input / output port of the material testing machine main body MTM via the connectors CN1 and CN2. Similarly, a short circuit for returning the loopback signal to the material tester main body MTM is also connected to the coupling detection circuit 18 via the connectors CN1 and CN2. Resistors 8A and 8B for performing electrical calibration of the load cell LC are connected to the analog circuit 12 of the material testing machine main body MTM via connectors CN1 and CN2.

  The load cell LC has a known bridge circuit and is connected to the connector CN3 of the cable unit CU via the connector CN4. Alternatively, an extension cable (not shown) is connected between the connector CN3 and the connector CN4 as necessary.

  Next, the circuit operation of FIG. 2 will be described. First, when the coupling detection circuit 18 detects the return of the loopback signal transmitted from the material testing machine main body MTM, it is determined that the cable unit CU is connected to the material testing machine main body MTM. When a loopback signal is stably detected, a voltage of 3.3 V (volt) is supplied to the power supply line connected to the digital input / output port. Since the current consumption of the memory circuit 6 is about several milliamperes, this digital input / output port can supply a maximum of 24 mA (milliampere) per line. Has supply capability.

  After the power supply line of the memory circuit 6 is set to 3.3 V, the stored data is read through the signal line of the memory circuit 6. Thereafter, the power supply line and the signal line are all maintained at 0 V (= ground potential). Here, the reason why the signal line of the memory circuit 6 is also fixed to 0 V is that the signal line of the memory circuit 6 becomes high level, and the power line is set to high level by the protection circuit (not shown). This is because a power supply voltage may be induced.

  In this manner, the cable unit CU can be removed without turning off the main power switch 16 during standby after access to the memory circuit 6 is completed. Since the resistors 8A and 8B, which are passive elements, are connected to the analog circuit 12 of the material testing machine main body MTM, there is no need to consider the power supply voltage.

  During the access period to the memory circuit 6, it is possible to notify the user that the cable unit CU is prohibited from being removed using a notification device (not shown) such as an indicator or a speaker. For example, it is preferable to provide an LED blink warning light (not shown) on the connector unit 2 (see FIG. 1).

  FIG. 3 is a circuit diagram for performing electrical calibration based on the calibration data read from the memory circuit 6. The electrical calibration here means that the gain adjustment is completed only by electrical processing when the gain adjustment of the instrumentation amplifier is performed on the user side. More precisely, the user calibrates the gain of the instrumentation amplifier by electrically reproducing the virtual load without actually applying the calibrated actual load to the load cell LC.

  The part enclosed with the broken line of FIG. 3 shows the material testing machine main body MTM. Here, 20 is a read circuit for reading calibration data from the memory circuit 6, 22 is an instrumentation amplifier for load cells, 24 is a gain control circuit for adjusting the gain of the instrumentation amplifier 22, and 35 is an instrumentation amplifier. A voltage measurement circuit for measuring the output voltage 22, 42 is a control panel, and 50 is a display attached to the control panel 42.

Prior to the electrical calibration, the offset component of the instrumentation amplifier 22 is adjusted so that the measured value X becomes zero with the load applied to the load cell LC set to zero. Next, by connecting the resistors 8A and 8B to the bridge circuit of the load cell, the maximum distortion of the load cell (that is, the virtual maximum load) is electrically realized. The gain of the instrumentation amplifier 22 is adjusted so that the measured value X ′ at this time becomes equal to the value X ₀ stored in the memory circuit 6. For this gain adjustment, a gain adjustment knob (not shown) of the instrumentation amplifier 22 may be manually operated. In the present embodiment, the gain control circuit 24 automatically performs gain adjustment. Thus, the electrical calibration operation performed by the user is completed.

  After the connection detection circuit 18 confirms the connection of the cable unit CU, the above-described electrical calibration is performed. In addition, the user gives a calibration instruction as necessary during the material test, so that the electrical calibration is performed. May be executed.

  FIG. 4 is an overall configuration diagram showing a material testing machine having the configuration shown in FIGS. 1 to 3. In this figure, LC is a load cell and CU is a cable unit. 31A and 31B are a pair of struts, and a ball screw (not shown) rotated by a motor (not shown) is housed therein. A cross head 32 moves up and down in accordance with the rotation of the ball screw. Reference numeral 34 denotes a base, and 36 denotes a cross yoke. Reference numeral 38 denotes an upper gripping tool, which is connected to the crosshead 32 via the load cell LC. Reference numeral 40 denotes a lower gripping tool, which is connected to the base 34. Reference numeral 42 denotes a control panel that includes not only a load mechanism (not shown) but also a display 50 (see FIG. 3), various interface circuits (not shown), and an arithmetic circuit (not shown) for performing various data processing. I have. KK is an extensometer. The material testing machine 44 according to the present embodiment is constituted by the above constituent elements.

-Effects and effects of the embodiment-
According to the present embodiment, the following actions and effects can be achieved.
(1) After driving power is supplied to the memory circuit 6 mounted in the cable unit CU from the digital input / output port of the main body of the material testing machine and access to the memory circuit 6 is completed, the memory circuit 6 Since the power supply line and the signal line are kept at the ground potential, the cable unit CU can be attached and detached while the main power supply of the material testing machine main body is turned on.
That is, in the conventional material testing machine, it is necessary to turn off the main power switch of the material testing machine body every time the load cell LC is replaced, but according to the present embodiment, it can be freed from such troublesomeness. . For example, even when four types of load cells as illustrated in FIG. 5 have to be replaced during the material test, a function corresponding to so-called hot-swapping can be realized without touching the main power switch. .
(2) Since the digital input / output port for connecting the power supply line and the signal line of the memory circuit 6 is configured using a commercially available FPGA, a material testing machine can be used without changing the conventional hardware configuration. The cable unit CU can be attached and detached while the main power switch 16 of the main body is turned on.
(3) Calibrating the output signal of the load cell using the calibration data read from the memory circuit 6 and the resistors 8A and 8B that electrically realize the maximum distortion (that is, the virtual maximum load) of the load cell. Therefore, the calibration processing operation performed each time the load cell and the cable unit are replaced can be executed very easily and quickly.
(4) Since the coupling detection circuit 18 for detecting that the cable unit CU is connected to the material testing machine main body is provided, drive power is supplied to the memory circuit 6 in response to the connection confirmation signal sent from the coupling detection circuit 18. Can be supplied.
(5) Since electric power is supplied to the memory circuit 6 in response to a calibration instruction given by an operator during material testing, electrical calibration is performed as necessary even during material testing. Can do.
(6) Since the gain of the load cell instrumentation amplifier 22 is automatically adjusted using the gain control circuit 24, electrical calibration can be automatically executed without manual operation.
(7) During the access period to the memory circuit 6, the LED for notifying the removal of the cable unit CU flashes. If there is no flashing, the main power switch 16 of the material testing machine main body is kept on. The cable unit CU can be attached and detached at any time.

-Modification-
Each component according to the present embodiment can be modified as listed below.
(1) In the above-described embodiment, the cable unit for connecting the load cell to the material testing machine main body has been described. However, it is of course possible to connect an extensometer or a displacement meter to the material testing machine main body without being limited to the load cell. It is. For example, an extensometer or an electrostatic displacement meter using a differential transformer can be connected via a cable unit. However, in the case of a load cell, an actual load is electrically realized using a resistor, but when an extensometer or a differential displacement meter using a differential transformer is connected, a reactance element is included. It is necessary to electrically realize the actual displacement using a passive circuit.
(2) In the embodiment described above, the memory circuit 6 is used as an active circuit for supplying power from the digital input / output port. However, the present invention is not limited to the memory circuit, and other digital ICs or linear ICs can be used.
(3) In the above-described embodiment, after the access to the memory circuit 6 is completed, the digital input / output port is set so that not only the power supply line but also the signal line is held at the ground potential. When using the power supply, consider the conditions such as the type, whether it is positive logic or negative logic, how the power supply voltage is specified, and what the function of the protection circuit is. It is necessary to set the potential of the line and the signal line to a predetermined potential. Since these conditions are design matters, detailed description is omitted.
(4) In the embodiment described above, the cable unit CU can be removed at any time after the access to the memory circuit 6 is completed. However, in order to realize safer removal, the user responds to the removal instruction. Thus, it is possible to prohibit access to the memory circuit 6. Specifically, when the removal of the cable connector CU is transmitted to the control panel 42 by operating an input device (not shown), an access prohibition interrupt is generated from a control circuit (not shown).

The above description is merely an example, and the present invention is not limited to the above-described embodiments and modifications unless the features of the present invention are impaired.
It goes without saying that the embodiment can be combined with one or more of the above-described modified examples. Further, the modification examples can be combined in any way.
Further, other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

It is the figure which showed typically the whole structure of the material testing machine to which this invention is applied. It is the circuit diagram which showed the electrical connection aspect of material tester main body MTM, cable unit CU, and load cell LC. 3 is a circuit diagram for performing electrical calibration based on calibration data read from the memory circuit 6. FIG. It is a whole block diagram which shows the material testing machine provided with the structure shown in FIG. It is explanatory drawing shown about replacement | exchange of a load cell.

Explanation of symbols

2 Connector unit 4 Substrate 6 Memory circuit 8A, 8B Resistor 10 Digital circuit 12 Analog circuit 14 Main power supply 16 Main power switch 20 Reading circuit 22 Instrumentation amplifier 24 Gain control circuit 35 Voltage measurement circuit 38 Upper grip 40 Lower grip 42 Control panel 50 Display unit CU Cable unit CN1 to CN4 Connector LC Load cell MTM Material testing machine body

Claims (8)

In a material testing machine that inputs a test force applied to a specimen or an output signal of a detector corresponding to a displacement generated in the specimen through a cable unit,
A digital input / output port for supplying drive power to an active circuit mounted in the cable unit;
First port control means for supplying the driving power from the digital input / output port only during a period in which the active circuit is in a predetermined operating state;
A second port control means for holding a power supply line and a signal line of the active circuit at a predetermined potential during a period when the active circuit is not in the predetermined operation state;
A material testing machine comprising: The material testing machine according to claim 1,
The material testing machine, wherein the digital input / output port, the first port control means, and the second port control means are configured using a programmable gate array. The material testing machine according to claim 1 or 2,
A material including a memory circuit as an active circuit mounted in the cable unit, and calibrating an output signal of the detector based on stored contents read from the memory circuit during a predetermined access period testing machine. In the material testing machine according to any one of claims 1 to 3,
The cable unit is mounted with a passive circuit in addition to the active circuit, and the passive element included in the passive circuit and the memory read out from the memory circuit included in the active element during a predetermined access period A material testing machine that calibrates an output signal from the detector based on a combination with contents. In the material testing machine according to any one of claims 1 to 4,
And further comprising a coupling detection circuit for detecting that the cable unit is connected to the material testing machine main body, wherein the first port control means responds to a connection confirmation signal sent from the coupling detection circuit. A material testing machine characterized in that a driving power is supplied to the machine. In the material testing machine according to any one of claims 3 to 5,
The first port control means causes the active circuit to supply power in response to a calibration instruction given from the outside. In the material testing machine according to any one of claims 4 to 6,
Instrumentation amplifier gain adjustment means for amplifying the output signal from the detector based on the stored contents read from the active circuit during a predetermined access period and the passive element included in the passive circuit is further provided. A material testing machine. The material testing machine according to any one of claims 1 to 7,
A material testing machine further comprising an informing means for notifying the removal of the cable unit during a period in which the active circuit is in a predetermined operation state.

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