JP3973004B2 - Initial test force setting method for indentation type hardness tester - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a push-type hardness tester, and more particularly to a method for loading the initial test force.
[0002]
[Prior art]
In general, the hardness test by the Rockwell hardness tester is based on the difference between the indentation depth in the initial test force state and the indentation depth in the test force state by pushing a diamond or steel ball indenter into the sample. The Rockwell hardness of the sample is calculated.
[0003]
That is, as shown in the flowchart of FIG. 4, after setting the load lever of the hardness tester to the neutral position (step C ₁ ), the sample stage is raised and the sample on the sample stage is pressed against the indenter to the same sample. Add the first test force F ₀ (step C _2). The sample stage is attached to the upper end of the square screw shaft as the sample stage shaft supported on the machine frame of the hardness tester so as to be movable up and down on the same axis as the indenter. It can move up and down by moving. The square screw shaft can be moved up and down by screwing it into the square screw shaft with a sample table motor as a sample table vertical movement mechanism and rotating the rotating bush supported rotatably on the machine frame in the forward and reverse directions. It has become. As a sample table vertical movement mechanism, a manual type in which a rotary bush is manually rotated is also known.
[0004]
After holding in this state (the state in which the initial test force F ₀ is applied to the sample) (step C ₃ ), the pressing force is gradually applied to the indenter (step C ₄ ), and finally the indenter is applied with the test force F _1. pressed against the sample (step C _5), remove the test force F ₁ from subsequent indenter (step C ₆₎ returned to the state of the preliminary test force (step C _7), the depth h ₁ pushing against sample of an indenter at this time Measure (Step C ₈ ).
[0005]
Then, based on the difference | h ₀ −h ₁ | between the indentation depth h ₁ of the indenter in step C ₃ and the similar depth h ₀ in step C ₇ , the Rockwell hardness HRC (in the case of the C scale) is calculated. calculate.
[0006]
After in step C ₈ Measurement of indentation depth, the sample stage was lowered by driving the sample stage motor, it removes the first test force from the sample (step C _9).
Here, the operation of applying the initial test force to the sample is performed by manually operating the sample stage vertical movement mechanism.
[0007]
[Problems to be solved by the invention]
Conventionally, the initial test force (usually about 98.07 N) is applied to the sample by manually operating the sample stage vertical movement mechanism while reading the load applied to the sample with a load sensor, as shown in the flowchart of FIG. It is.
That is, in the conventional method of applying the initial test force to the sample by manual operation, the sample stage is raised to apply the initial load to the sample (step D ₁ ). At this time, the load detected by the load sensor is reduced. When the predetermined initial test force is reached, the operation of the sample stage motor (or manual rotation operation: the same applies hereinafter) is stopped, and at the same time when the sample stage is stopped by applying an automatic brake, there is a risk of overshoot. Therefore, in general, in anticipation of overshoot, when the load reaches 85 to 90% of the initial test force (step D ₂ ), the operation of stopping the operation of the sample table motor and applying the automatic brake (step D ₃ ). The sample stage is stopped (locked) (step D ₄ ).
[0008]
Therefore, in the conventional manual operation method, a predetermined initial test force cannot be accurately applied to the sample, and there is a problem that the initial test force varies depending on the speed at which the sample stage is raised.
The present invention is intended to solve such problems.
[0009]
[Means for Solving the Problems]
The present invention includes a machine frame, a load lever whose base end is pivotally supported by the machine frame, and an indenter attached to the tip, a motor that is attached to the machine frame and can apply a test load to the load lever, A sample stage shaft that is mounted on the machine frame so as to be movable up and down and on which a sample can be placed, and a sample stage axis that is provided at the upper end, and a sample stage that is mounted on the machine frame to move the sample stage axis up and down. In the indentation type hardness tester having a dynamic mechanism, and performing the hardness test of the sample based on the difference in indentation depth between the initial test force and the test force against the sample by the indenter, the sample The sample table is moved up and down by the sample table vertical movement mechanism until a load slightly lower than the predetermined initial test force is applied to the sample table, and then the sample table vertical movement mechanism is stopped and the motor is driven via the load lever. The above indenter It is a means to solve problems as to set the first test force by pressing the charge.
[0010]
In addition, a load sensor is provided on the load lever, and the motor is controlled by a control circuit that feeds back the indentation load applied to the sample by the indenter detected by the load sensor.
[0011]
In the initial test force setting method in the indentation type hardness tester of the present invention described above, the sample stage is moved forward by the sample stage vertical movement mechanism to raise the sample stage, and a predetermined amount is applied to the sample placed on the sample stage. After applying a load slightly lower than the initial test force (force: initial test force -α), the motor is driven, the load lever is pulled down, and the indenter is pressed against the sample to apply the predetermined initial test force. The initial test force can be set.
[0012]
Further, since the motor control circuit is configured to feed back the indentation load applied to the sample by the indenter, the initial test force can be set with high accuracy without causing overshoot.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an initial test force setting method in a push-in type hardness tester as an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an example of an apparatus suitable for carrying out the method, and FIG. A flowchart showing the initial test force setting procedure, and FIG. 3 is a block diagram showing the configuration of the control unit.
[0014]
In FIG. 1, reference numeral 10 denotes a machine frame of the hardness tester. A load lever 11 is supported at the upper left end of the machine frame 10 by a horizontally arranged cross spring 12 so as to be swingable. Arranged.
[0015]
A load spring lever 14 extending in parallel with the load lever 11 is disposed below the load lever 11 with its base end (left end) integrally attached to the vicinity of the base end of the load lever 11. Yes.
The load lever 11 is rich in rigidity, and is formed in a shape and size so as not to cause (elastic) deformation even when a test force described later acts on the load spring lever 14.
[0016]
On the other hand, the load spring lever 14 is functionally similar to a leaf spring and has a weaker rigidity than the load lever 11, and causes a minute (elastic) deformation when a test force described later acts on the load spring lever 14. Is set to
[0017]
Alternatively, the load lever 11 and the load spring lever 14 may be formed in a bifurcated integrated structure, and the base end portion thereof may be attached to the machine frame 10 by the cross spring 12 so as to be swingable.
The load lever 11 is formed longer than the load spring lever 14, and an indenter 15 is attached to the lower surface of the tip (right end) thereof.
[0018]
Reference numeral 13 designates a coil spring interposed between the machine frame 10 and the lower surface of the load spring lever 14, and this coil spring 13 is used when the test force is not applied to the load spring lever 14. An action of holding in the neutral position (the state where the center of the cross spring 12 and the tip of the indenter 15 are located on the horizontal line aa as shown in FIG. 1) is performed.
[0019]
The machine frame 10 is further provided with a sample support device 20 on the same axis bb as the indenter 15 in the neutral position. This sample support device 20 includes a square screw shaft 21 as a sample stand shaft, a sample stand 22 attached to the upper end of the square screw shaft 21, an auto brake (electromagnetic brake) 23 capable of locking the square screw shaft 21, and a sample. It comprises a sample table motor 26 as a table vertical movement mechanism, a rotating bush 25 and a gear device 24 which are screwed into a square screw shaft 21 and move the square screw shaft 21 up and down by the rotation of the motor 26. By rotating the table motor 26 forward and backward, the sample table 22 can be moved up and down along the axis b. The sample support device 20 has the same configuration as the conventional one. Note that the sample table vertical movement mechanism may be configured by a mechanism that can rotate the rotating bush 25 manually and move the sample table 22 up and down instead of the sample table motor 26.
[0020]
Reference numeral 30 denotes a motor attached to the machine casing 10, and the motor 30 can apply a test force to the load spring lever 14.
That is, the ball screw joint 31 is attached to the rotating shaft 30 a of the motor 30, and the pressing body 32 is swingably connected to the upper end portion of the ball screw joint 31 with the horizontal shaft 33. The pressing body 32 is provided with a pressing piece 32a that engages with the upper surface of the load spring lever 14. By moving the pressing body 32 downward by the motor 30, the load spring lever 14 is rotated clockwise in FIG. The test force can be applied to the sample T placed on the sample table 22 via the lever 11 and the indenter 15.
[0021]
A sensor (indentation depth sensor) 40 for measuring the indentation depth of the indenter 15 is attached to the upper right end portion of the machine frame 10.
That is, the indentation depth sensor 40 is disposed with its body bottom fixed to the machine frame 10, and the tip (upper end) of the measuring element 40 a is always in contact with the lower surface of the load lever 11. . Reference numeral 41 denotes a signal lead wire for the push-in depth sensor 40.
[0022]
A sensor (load sensor) 50 for detecting a test force applied to the sample T on the sample table 22 by the indenter 15 is attached to the load lever 11.
That is, the load sensor 50 has its body side face fixed to the load lever 11 downward, and the tip (lower end) of the probe 50 a comes into contact with the upper surface of the load spring lever 14. Reference numeral 51 denotes a lead wire for taking out a signal from the load sensor 50.
[0023]
The detection values of the indentation depth sensor 40 and the load sensor 50 are sent to the control unit 60 via lead wires 41 and 51, respectively.
[0024]
As shown in FIG. 2, the control unit 60 receives a signal A of the push-in depth sensor 40 and receives a first counter 61 as an input device of the MPU 63 and a signal B of the load sensor 50 as a second input device of the MPU 63. In addition to a D / A converter 64 and a 1-bit open collector 65 as an output device of the counter 62 and MPU 63, a ROM 66, a RAM 67, a display / input unit 68, a clock 69, and the like are provided.
[0025]
The output signal C from the D / A converter 64 is input to the motor driver 70, and the output signal D from the 1-bit open collector 65 is used to control the autobrake 23. In the above configuration, the initial test force F ₀ is loaded according to the procedure shown in the flowchart of FIG.
[0026]
That After setting the load lever 11 to the neutral position, by rotating the sample stage motor 26 (or manually: the same applies hereinafter) to increase the sample base 22 (Step A _1).
[0027]
As the sample stage 22 rises, the sample T on the sample stage 22 is pressed against the indenter 15. This pressing force increases as the sample stage 22 rises, and the value (load) is detected by the load sensor 50. In other words, the load lever 11 is rotated counterclockwise around the cross spring 12 by the above pressing, but the load spring lever 14 is prevented from rotating counterclockwise by the pressing body 32. The load spring lever 14 is elastically deformed by 11 counterclockwise rotation, and the amount of deformation is detected by the load sensor 50 as the pressing force of the indenter 15 against the sample T.
[0028]
When the load reaches a value slightly lower than the predetermined initial test force F ₀ by an amount β (step A ₂ ), the operation of the sample table motor 26 and the operation of the auto brake 23 are performed, and the sample table 22 Is locked (step A ₃ ). The lock is released after a few seconds.
[0029]
Next, the motor 30 is rotated forward to pull down the pressing body 32. Loading lever 11 with force spring lever 14 by this operation is rotated in the clockwise direction around the cross spring 12, the pressing force to the sample T is increased (Step A _4). Rotation of the motor 30 is performed until the pressing force (load) reaches the preliminary test force F _0, pressing force that has reached the preliminary test force F ₀ is detected by the load sensor 50 (Step A _5: YES) Then, the motor 30 stops (step A ₆ ).
[0030]
It goes without saying that the above steps A ₁ → A ₆ are automatically performed by the operation of the control unit 60 based on the signals A and B (except in the case of manual operation at step A ₁ ).
[0031]
Thus, in this embodiment, when applying the initial test force F ₀ to the sample T, the load applied to the sample T is always detected, and the motor 30 is rotated while comparing the detected value with the predetermined initial test force. Since the control is performed to set a predetermined initial test force F ₀ , that is, the rotation control of the motor 30 is performed by feeding back the load applied to the sample T, the initial test force F ₀ is accurately determined. It can be added to the sample.
[0032]
After the initial test force F ₀ is applied to the sample T, the hardness test can be performed by sequentially executing steps C _{3 to} C ₉ in FIG.
[0033]
In this embodiment, additional load (Step C ₄₎ is carried out by further forward rotation of the motor 30, Step C _6, C ₉ is performed by reversely rotating the motor 30.
[0034]
In the measurement of the indentation depth (step C ₈ ), the detection value of the indentation depth sensor 40 in step C ₅ corresponds to h _1, and the detection value of the indentation depth sensor 40 in step C ₇ corresponds to h ₀ . Thus, the MPU 63 calculates the difference between the two detection values of the indentation depth sensor 40, and the MPU 63 performs an operation for converting the calculated value into the Rockwell hardness. The display unit 68 displays the Rockwell hardness. Is done.
[0035]
Needless to say, a series of operations from the step C ₂ to apply the initial test force to the end of the test (step C ₁₀ ) is performed by the automatic operation by the control unit 60.
[0036]
Thus, according to this embodiment, in the Rockwell hardness test, the initial test force can be applied to the sample with high accuracy, and a series of hardness tests following the load of the initial test force can be fully automated. Is possible.
[0037]
【The invention's effect】
As described in detail above, according to the initial test force setting method in the indentation type hardness tester of the present invention, the following effects can be obtained.
(1) Raise the sample table and apply a load (force) slightly lower than the predetermined initial test force to the sample placed on the sample table, then drive the motor and swing the load lever to move the indenter. Since a predetermined initial test force is applied by pressing the sample, it is possible to set an accurate initial test force.
(2) Since the motor is controlled by a control circuit that feeds back the indentation load on the sample by the indenter, the initial test force can be set with high accuracy without causing overshoot.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of an apparatus suitable for carrying out the present invention.
FIG. 2 is a block diagram showing a configuration of a control unit of the apparatus.
FIG. 3 is a flowchart showing a procedure for setting the initial test force.
FIG. 4 is a flowchart showing the procedure of a conventional Rockwell hardness test.
FIG. 5 is a flowchart showing a procedure for setting the initial test force.
[Explanation of symbols]
10 Airframe
11 Load lever
12 Cross spring
13 Coil spring
14 Load spring lever
15 Indenter
20 Sample support device
21 Square screw shaft as sample table axis
22 Sample stage
23 Auto brake
24 Gear unit
25 Rotating bush
26 Sample stage motor
30 motor
30a Motor rotation shaft
31 Ball screw joint
32 Press body
32a Pressing piece
33 Horizontal axis
40 Indentation depth sensor
40a Measuring depth of indentation depth sensor
50 Load sensor
50a Load sensor gauge
60 Control unit
61 First counter as input device
62 Second counter as input device
63 MPU
64 D / A converter
65 1-bit open collector
66 ROM
67 RAM
68 Display input section
69 clock
70 Motor driver F ₀ Initial test force F ₁ Test force

Claims (2)

A machine frame, a load lever pivotally supported by the machine frame and having an indenter attached to the tip, a motor attached to the machine frame and capable of applying a test load to the load lever, and the machine frame A sample stage shaft provided at the upper end of a sample stage that can be moved up and down, and a sample stage vertical movement mechanism that is attached to the machine frame to move the sample stage axis up and down. In addition, in the indentation type hardness tester in which the hardness test of the sample is performed based on the difference in indentation depth between the initial test force and the test force with respect to the sample by the indenter, the sample is subjected to a predetermined initial strength. After raising the sample stage together with the sample stage axis by the sample stage vertical movement mechanism until a load slightly lower than the test force is applied, stop the sample stage vertical movement mechanism and lock the sample stage axis with a brake. To the above Characterized in that to carry out the setting of the first test force by driving the motor presses the indenter into the sample through the loading lever, preliminary test force setting method in push-hardness tester. 2. The motor is controlled by a control circuit in which a load sensor is provided on the load lever, and a pressing load applied to the sample by the indenter detected by the load sensor is fed back. The initial test force setting method in the indentation type hardness tester described in 1.

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