JPS5821219B2 - Constant stress creep tester - Google Patents

Description

[Detailed description of the invention] The present invention relates to a stationary creep test machine,
More specifically, the present invention relates to a testing machine for performing a creep test under a constant stress on polymeric materials such as thermoplastic resins, fibers, and rubber.

Among the various tests performed to determine the mechanical properties of polymer materials, the most widely used test is the tensile test.

The process of applying a certain amount of stress to a sample and measuring its deformation over time is called a creep test.

An ideal leap test requires that a predetermined stress σ be suddenly applied to a sample that has not been subjected to any external force in the past, and then kept constant.

However, when using a conventional tensile test, the stress σ
cannot be applied instantaneously; it requires a finite amount of time.

Furthermore, in order to keep the stress constant, the load must be controlled according to the change in cross-sectional area due to sample deformation.

Since it is extremely difficult to control the load in conventional dead weight type creep testing machines, a constant load creep test is generally performed.

As a creep test device that controls the load according to the cross-sectional area change due to deformation of the sample, for example, the Japanese Patent Publication No. 43-2
It is described in Japanese Patent No. 5754 and is known.

In the apparatus described in this publication, when the total amount of deformation of the sample is large, the maximum overall length of the apparatus, especially when a constant temperature bath is attached, is the limit of the size of the constant temperature bath.

Also.

Creep tests are often conducted at high temperatures, but the test RJ holding clamps of conventionally known creep test equipment are of parallel plates or models, and if both ends of the sample are held by the holding clamps at the same time under high temperatures, There is a problem in that the sample sag due to thermal expansion and it is not possible to apply a predetermined stress r instantaneously.

In such a case, first only one end of the sample is held with a holding clamp, and when the sample reaches the measurement temperature, the other side of the sample is held.

However, with conventional parallel plate or model clamps, it is necessary to open the door of the thermostatic chamber to operate, and during this operation, it is unavoidable that the temperature inside the thermostatic chamber decreases, and the sample is again brought to the measurement temperature. In view of this situation, the inventors of the present invention have developed a method that does not make the device large, allows for easy attachment and detachment of the sample, and further reduces the load according to the change in cross-sectional area due to the deformation of the sample. The present invention has been completed as a result of extensive research aimed at providing a controlled constant response creep tester.

The gist of the present invention is to provide a load detection device, a sample-fixing-side clamp connected to the load-detecting device, and a sample-pulling roll clamp comprising a pair of rolls provided opposite to the sample-fixing-side clamp. This roll clamp for pulling a sample is equipped with a means for approaching and separating the roll gap, and further includes a means for applying a constant stress to the sample, the initial cross-sectional area S of the sample.

S from the input device, stress σ setting device, and stretching amount d1(t) detector, respectively.

, σ, and old (t) are input to the calculator, the tension F(t) is calculated, and the tension F(t) and the measured tension F'(t) detected from the load detector are input into the PID amplifier. and a control circuit for driving a pair of roll clamps so that the electrical difference between the two roll clamps is supplied to the ground and the electrical difference between the two roll clamps becomes constant.

Hereinafter, the constant dynamic creep tester according to the present invention will be explained in detail based on the drawings, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

FIG. 1 is a schematic side view of a testing machine Q-example according to the present invention;
The figures are a schematic plan view of the section 1--1 in FIG. 1, FIG. 3 is a schematic longitudinal cross-sectional side view of the section I-1 in FIG. 2, and FIG. 4 is a block diagram.

In the figure, 1 is a load detection device, 2 is a clamp on the sample fixed side, 3 is a sample, 4 is a fixed roll, 5 is a moving roll, 6 is a drive shaft of the fixed roll 4, 7 and 7' are rotation bearings, 8, 8 ′
1 and 2 respectively show the brackets of the rotary bearings 7 and 7'.

9 is a drive shaft of the moving roll 5, 10 is a taper pin, 11 is a universal joint, 12 is a pin, 13 is a drive shaft,
14 and 15 are gears, and 16 and 16' are drive shafts 9.
, 13, and 17.17' indicate the slide brackets of the rotation bearings 16.16', respectively.

18 is a guide shaft of the drive shaft 9; 19 is a moving shaft of the drive shaft 9; 2
0 is a dedicated bearing for the moving shaft 19, 21 is a bracket for the bearing 20, 22 is a connecting rod, 23 is an ete cylinder, 24 is a base plate, 25 is a support column, 26 is a thermostatic chamber, 27 is a door, 28
29 indicates a sample tray, 29 indicates a sample tube, and 30 indicates a sample tip.

31 is a variable speed reducer with clutch and brake, 32 is a servo and
Motor, 33 is a solenoid valve, 34 is a tacho generator, 3
5 is a speed converter, 36 is a servo amplifier, 37 is a speed setting device, 38 is a slit disk, 39 is a pulse sensor, 4
0 is a preset counter, 41 is a D/A converter, 42 is a strain meter, 43 is an interlocking switch,
44 is a calculator, 45 is a sample cross-sectional area (So) input device, 4
6 is a stress (σ) setting device, 47 is a PID amplifier, 48 is a switch, 49 is a clutch/brake/electromagnetic valve manual operation circuit, 50 is an extension amount output end, 51 is a load output end, and 52 is an air source. .

The constant force creep tester according to the present invention includes a load detection device 1
A sample fixing side clamp 2 connected to this load detection device is provided, and a stress loading roll consisting of a pair of rolls 4 and 5 is further provided opposite to this sample fixing clamp 2.

As shown in FIG. 1, the load detection device 1 is supported by a column 25 on one side, and a sample fixing side clamp 2 is provided on the other side.

The sample fixing side clamp 2 can be of a conventionally known structure such as a model, a parallel plate type, or an eccentric roll type.

The constant force creep tester according to the present invention fixes one end of the sample 3 with the sample fixing clamp 2, fixes the other end with a pair of roll clamps, and rotates the rolls 4 and 5 in opposite directions. It has a structure that applies controlled stress according to the change in cross-sectional area due to the deformation of the sample 3.

One of the pair of rolls is called a fixed roll, which can rotate freely but cannot move in any other way.

The fixed roll 4 is attached to a drive shaft 6 and has a rotation bearing 7.
, 7' and brackets 8.8' to the base plate 24.

The other roll 5 can not only rotate, but also move the sample 3 toward the fixed roll or move away from the sample 3.

In this way, in a pair of roll clamps that apply stress to the sample, one is a fixed roll and the other is a moving roll, but the means for moving the moving roll towards and away from the fixed roll has the following structure. Can be assembled.

That is, a moving roll guide shaft is provided below or above the moving roll 5 in a direction perpendicular to the axial center of the fixed roll 4, and is connected to the moving roll 5 and is perpendicular to the axial center of the fixed roll 4. It is preferable to provide a compressed air cylinder machine for approaching and separating moving rolls in both directions.

The moving roll 5 is connected to a drive shaft 9, and this drive shaft 9 is attached to a rotation bearing 16.

One end of the drive shaft is provided with a taper pin 10 and a universal joint 11, which are incorporated into a slide bracket 17 together with a rotation bearing 16.

The other end of the universal joint 11 is connected to a pin 12 and a drive shaft 13, and the drive shaft 13 is assembled into a bracket t-17' together with a rotary bearing 16' so that it can rotate freely.

The drive shaft 6 and the drive shaft 13 are configured to rotate simultaneously through gears 14 and 15.

That is, when the drive shaft 6 is rotated by some means, the gear 14 rotates, and this rotation is caused by the gear 15 to rotate the drive shaft 1.
As a result, the fixed roll 4 and the moving roll 5 can be rotated simultaneously.

The moving roll 5 can approach and move away from the fixed roll 4 while keeping its axis parallel to the axis of the fixed roll 4.

For this purpose, a moving roll guide shaft 18 is provided above or below the moving roll 5 in a direction perpendicular to the axis of the fixed roll, and connected to the moving roll 5 and in a direction perpendicular to the axis of the fixed roll. , a compressed air cylinder mechanism for driving the moving rolls 5 toward and away from each other is provided.

In this case, when the movable roll guide shaft 18 is provided below the movable roll 5, it is not necessary to provide it immediately below the movable roll 5;
As shown in the drawings and FIG. 3, it is preferable that the drive shaft 9 be provided below the slide bracket 17 of the drive shaft 9 so that the drive shaft 9 and the rotary bearing 16 within the slide bracket 17 can be moved together.

The compressed air cylinder mechanism for approaching and separating, as shown in FIG. It is preferable to support it with a bearing 20 attached to a plate 24 and protect it with a bracket 21.

When compressed air is introduced into the air cylinder 23, the piston inside the cylinder moves to the right in Figure 2.The movement is as follows:
The connecting rod 22 reaches the slide bracket 17 of the drive shaft 9 via the moving shaft 19.

As a result, the slide bracket 17 of the drive shaft 9 moves toward the drive shaft 6 along the movable roll guide shaft 18, and the movable roll 5 is pressed against the fixed roll 4 side.

When compressed air to the air cylinder 23 is sent to the connecting rod side, the piston inside the cylinder 23 can be moved to the left side.

The constant stress creep tester according to the present invention further includes means for applying a constant stress to the sample.

FIG. 4 is a block diagram of a testing machine according to the present invention.

One end of the sample 3 is fixed with a sample fixing side clamp, and when starting the creep test, the other end is clamped with a fixed roll 4 and a moving roll 5, and the rolls 4 and 5 are rotated to apply stress to the sample. Give σ.

A means for controlling the load according to the cross-sectional area change due to the deformation of the sample at this time can be configured as follows.

S is the cross-sectional area of the sample before starting the creep test.

, the distance between the sample fixing side clamp and the stress-loading roll clamp is 1, the sample is stretched by (1) at time t r&, and assuming that Poisson's ratio is 0.5 or close to it, at t The cross-sectional area S (t) of the sample is expressed by the following equation (1).

Further, if the force at that time is F(t), the stress σ is expressed by the following equation (2).

σ=F(t)/5(t)・・・・・・・・・・・・
...(2) Utilizing the above relationship, so that the force F detected by the load detection device 1 and the strain meter 42 follows F(t) derived from equation (2), By controlling the rotational speed of the fixed roll 4 and the moving roll 5 and applying a constant stress to the sample, a constant force creep test can be performed.

F(t) is expressed as follows from equations (1) and (2) above.

F(t) in equation (3) is calculated by the arithmetic unit 44.

For So, measure the sample to be subjected to the creep test in advance, and use this value as S.

The signal is supplied from the input device 45 to the arithmetic unit 44 .

σ is an arbitrary value and is supplied from the σ setter 46 to the arithmetic unit 44.

The old (1) is obtained from the output of the D/A converter 41, and 1
is the distance between the sample-fixing side clamp and the stress-loading roll clamp, which is a device constant.

F(t) in equation (3) is calculated by the arithmetic unit 44 by supplying various variables and constants to the arithmetic unit 44 as described above.

The output F(t) of the calculator 44 and the strain meter 4
The two outputs F are respectively supplied to a PTD amplifier 47 via a switch 43, and the output thereof is supplied to a servo amplifier 36 via an interlocking switch 43.

The servo motor 32 is configured such that the force F detected by the load detection device 1 and the strain meter 42 is the output F(t
) The rotation speeds of the fixed roll 4 and the moving roll 5 are controlled so as to follow the rotation speed.

In order to shorten the run-up period until the set stress σ is reached as much as possible, it is preferable to rotate the roll clamp at a high speed.

The constant stress creep characteristic of the sample can be obtained by recording the output of the D/A converter from the stretching amount output end 50 as a relationship with time.

The constant force creep tester according to the present invention has the above-mentioned structural features, but when performing a creep test in a high temperature atmosphere, as shown in FIG. The roll clamp for stress loading is placed in a constant temperature bath 2.
It can be installed within 6.

When a creep test is conducted at high temperatures, the amount of sample deformation is generally large, but a sample tray 28 can be installed below the stress-loading roll clamp to receive the sample. A hole is made in the sample tray 28, and a constant temperature bath 26 is added.
It is also possible to provide a sample tube 29 on the heat insulating wall surface of the sample tube 29 through which the sample can pass, and a sample tip 30 for receiving the sample below the sample tube 29.

When the sample 3 is in the form of a sheet or film, the thickness decreases as the amount of stretching increases, but the clamping force can be kept constant by adjusting the amount of compressed air sent to the air cylinder 23.

The testing machine according to the present invention can be used as a constant force creep test machine by setting the interlocking switch 43 to position A, and by switching the interlocking switch 43 to position B for constant strain rate tensile testing. Can be used as a machine.

In order to give a constant strain rate to the sample 3, the rotation speed of the roll 4.5 must be constant.

A servo motor 32 is used to provide a constant rotation speed to the rotor 4.5.

A tachometer generator 34 is connected to the servo motor 32. When the servo motor 32 rotates, the tachometer generator 34 generates a voltage proportional to the rotation, which is sent to the servo amplifier via a speed converter 35. The rotation speed of the servo motor 32 is controlled so that the voltage from the speed converter 35 follows a reference constant voltage supplied from the speed setter 37.

A slit disk 38 is attached to the drive shaft 6, a pulse sensor 39 detects the slit in the disk, and a preset counter 40 adds up the amount of stretching of the sample.

The number of slits in the slit disk 30 is preferably set in a specific relationship with the circumference of the roll 4.

For example, if the circumference of the roll is 100 mm and the number of slits in the slit disk is 100, one slit represents 1 mm.

The force generated when the sample 3 is stretched is applied to the sample fixing side clamp 2.
If this is connected to the load detection device 1 and this is connected to the strain meter 42, it can be connected to the load output end 51 and recorded.

The amount of stretching of the sample 3 can be recorded by converting the amount accumulated by the preset counter 40 into an analog value using the D/A converter 41 and connecting it to the stretching amount output terminal 50.

If switch 4B is set to automatic on the X side, operations such as clamping the sample, recording strain loading, stress, and stretching amount can
Can be carried out by automatic circuit.

If the switch 48 is switched to manual mode on the Y side, the stretching operation can be performed manually.

In the case of manual operation, the clamping of the sample, the strain load, etc. can be operated independently by the clutch/brake/electromagnetic valve manual operation circuit 49.

When performing a tensile test using the apparatus according to the present invention as a constant strain rate tensile tester, the behavior of the sample under a constant strain rate can be known by recording the relationship between the load and the amount of stretching.

In this case, the elongational viscosity μE(t) is calculated by setting the distance between the sample fixing side clamp and the stress loading roll clamp to 1, and the sample 3
The cross-sectional area of is S.

, where F is the load output, dl(t) is the amount of stretching of the sample, and U is the stretching speed, it can be calculated using the following equation (4).

The steady-state dynamic creep tester according to the present invention has the following advantages, and its industrial utility value is extremely high.

(1) According to the testing machine of the present invention, since the sample is clamped by adjusting the air pressure of the air cylinder, the sample can be quickly and easily attached and detached by simply turning on and off an electric switch.

(2) The force for clamping the sample can be changed arbitrarily by adjusting the air pressure of the air cylinder, so even if the sample is stretched and its thickness is reduced, the sample can always be clamped with a constant pressure.

(3) Even when testing at high temperatures, the sample can be clamped and unclamped without opening the thermostatic chamber door, making it possible to obtain various highly accurate data.

(4) Since the acceleration of applying the load to the sample or the amount of load can be arbitrarily changed, the influence of the acceleration of applying load or the amount of load on creep can be easily investigated.

(5) Since a means for applying a constant stress to the sample is provided, the load can be controlled according to the change in cross-sectional area due to the deformation of the sample, and a constant stress creep test can be performed.

(6) By changing the stress setting value at the measurement stage,
Tests with superimposed stress can be performed.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a schematic side view of an example of a test device according to the present invention;
The figure is a plan view of the ■-■ part of Figure 1, and Figure 3 is a plan view of the section ■-■ of Figure 1.
FIG. 4 is a vertical cross-sectional side view of the I-1 section in the figure and a block diagram. In the figure, 1 is a load detection device, 2 is a sample fixing side clamp, 3 is a sample, 4 is a fixed roll, 5 is a moving roll, 6 is a drive shaft of the fixed roll 4, 9 is a drive shaft of the moving roll 5, 1
0 is taper pin, 11 is universal joint, 13
is a drive shaft, 14.15 is a gear, 18 is a guide shaft of the drive shaft 9, 19 is a moving shaft of the drive shaft 9, 22 is a connecting rod, 23 is an air cylinder, 24 is a base plate, 26 is a constant temperature bath, 31
32 is a servo morph, 33 is a solenoid valve, 34 is a tacho generator, 35 is a speed converter, 36 is a servo amplifier, 37 is a speed setting device,
38 is a slit disk, 39 is a pulse sensor, 40 is a preset counter, 41 is a D/A converter, 42
is a strain meter, 43 is an interlocking switch, 44 is a calculator, and 45 is S. An input device, 46 a σ setting device, 47 a PID amplifier, 48 a switch, 49 a clutch/brake/electromagnetic valve manual operation circuit, 50 an extension amount output end, 51 a load output end, and 52 an air source. .

Claims (1)

[Claims] 1 Equipped with a load detection device, a sample-fixing-side clamp connected to the load-detecting device, and a sample-pulling roll clamp consisting of a pair of rolls provided opposite to the sample-fixing-side clamp. The clamp is
The initial cross-sectional area of the sample So
From the input device, stress σ setting device, and extension di(t) detector, So, σ, and old(t) are inputted to the calculator, respectively, and F(t
) = a S e upper P1 The tension F(t) is calculated, and the tension F(t) and the measured tension F'(t) detected from the load detector are supplied to the PID amplifier, and the electric A constant creep test machine characterized in that it is equipped with a control circuit that drives a pair of roll clamps so that the difference in temperature becomes even.