JPH04249756A - Measuring method of expansion characteristic - Google Patents

Abstract

PURPOSE:To measure the expansion characteristic of a sample simply and quantitatively by applying a prescribed load onto the sample enclosed in a sample chamber, by heating it and by detecting a stroke of a sample presser and a heating temperature on the occasion. CONSTITUTION:A sample 1 is packed in a cylinder 11 and a prescribed load is applied onto the sample 1 through a piston 13. The sample 1 is heated by controlling a heater 12 by a control circuit 30 through an input-output circuit 24 and thereby an equal-speed rise in temperature is started, while a printer 23 is started. A sample chamber temperature from a temperature detector 22 and a piston stroke from a stroke meter 21 are made to correspond to each other and stored in a memory 32. When the end of a test is determined, the printer 23 records graphs of a heating temperature and the stroke and determines a start point of expansion by using them. Next, an output signal of the stroke meter 21 at the start point of expansion and the heating temperature corresponding thereto are stored. Then, the output signal of the stroke meter 21 at an end point of expansion and the heating temperature corresponding thereto are stored. Then, the rate of expansion is determined by a prescribed formula.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring expansion characteristics suitable for measuring the expansion rate of rubber and food products such as biscuits.

0002

2. Description of the Related Art For example, when injection molding rubber that expands at a predetermined temperature or higher, it is necessary to injection mold the rubber material while heating it to a predetermined temperature or higher. When injection molding such rubber, conventionally a preliminary test is carried out in advance to determine the optimum temperature. However, there are problems in that performing this preliminary test is complicated and it is also difficult to determine the optimum temperature, so it is desirable to quantitatively measure the expansion characteristics of the rubber material.

Conventionally, in order to measure the expansion characteristics of such a sample, a viscometer called a capillary rheometer is used to extrude a molten sample from a thin tube, and the outer diameter of the flowing sample is visually observed and compared with the diameter of the thin tube. .

0004

However, this conventional technique has a problem in that the expansion characteristics cannot be quantitatively detected. In addition, Japanese Utility Model Application Publication No. 19963/1983 discloses a device that heats and maintains a sample sealed in a sample chamber at a constant temperature, applies a load to the sample while controlling the position of a crosshead, and detects the change in volume at that time. Disclosed. However, since it is difficult to control the load at a constant level with this device, it is virtually impossible to measure the expansion characteristics of the sample by increasing the heating temperature while keeping the load constant.

An object of the present invention is to provide a method for simply and quantitatively measuring the expansion characteristics of a sample.

[0006]

[Means for Solving the Problems] The measurement method according to the present invention applies a constant load to a sample sealed in a sample chamber via a holding device, heats the sample while keeping the constant load, and adjusts the stroke of the sample holding device. Measure the heating temperature, record a graph of the stroke and heating temperature, detect the point at which the sample starts expanding based on the graph, and quantitatively detect the expansion characteristics of the sample after the expansion starts from the graph. It is something.

[0007]

[Operation] The expansion start point is detected from the graph of heating temperature and stroke, and the expansion characteristics of the sample can be quantitatively understood from the subsequent behavior of the graph.

[0008]

[Embodiment] One embodiment will be explained with reference to FIGS. 1 to 5. Figure 2
3 shows a mechanical part of an apparatus using the expansion characteristic measuring method according to the present invention, and FIG. 3 shows its control system. Mechanism section 1 shown in FIG.
0 is basically the same as that used in a conventionally known capillary rheometer, and this mechanism part 10
consists of a bottomed cylinder 11 filled with sample 1, a heater 12 provided on the outer periphery of this cylinder 11, a piston 13 that pressurizes sample 1, and a load loading mechanism 14 that applies a predetermined load to piston 13. have The load mechanism 14 includes a lever 142 that swings around a fulcrum 141.
A weight 143 suspended from the tip of the lever 142 applies a clockwise moment to the lever 142 to apply a load to the piston 13. Note that a plug 15 is screwed into the bottom of the cylinder 11 for taking out the sample after the test.

In FIGS. 2 and 3, 21 is a stroke meter that detects the stroke of the piston 13, and 22 is a temperature detector that detects the sample chamber temperature.The outputs of these are sent to a microcomputer (CPU) 31 and a memory 32. The signal is input to a control circuit 30 mainly composed of. 23 is a printer, which outputs an input/output circuit 24 according to an output signal from a control circuit 30;
is driven through the piston to record a graph of heating temperature and piston stroke as shown in Figure 5. 25 is a keyboard for the examiner to input various data.

Next, the procedure for measuring the expansion characteristics, particularly the expansion coefficient, will be explained based on FIGS. 1 and 4. First, cylinder 11
A weight 143 is suspended from the tip of a lever 142, and a constant load is applied to the sample via the piston 13. In this state, when a start switch (not shown) instructs to start the test, the program shown in FIG. 1 is started. First, in step S1, from the control circuit 30 to the input/output circuit 24,
The sample 1 is preheated by controlling the heater 12 via the step S2, and when it is determined in step S2 that the preheating is finished, the process proceeds to step S3. In step S3, the heater 12 starts to raise the temperature at a constant rate, and the printer 23 is activated. Step S4
When it is determined that it is the data sampling time, step S5
Then, the sample chamber temperature from the temperature detector 22 and the piston stroke from the stroke meter 21 are stored in the memory 32 in association with each other. When it is determined in step S6 that the test has ended, data processing calculations are performed in step S7, and this procedure is ended. In parallel with these steps, the printer 23 records a graph of heating temperature and stroke as shown in FIG.

FIG. 1 shows details of the data processing operation in step S7 shown in FIG. In step S11, all data on the heating temperature and stroke are read, as well as the sample length and cylinder cross-sectional area. Note that the values of the sample length and cylinder cross-sectional area are input in advance from the keyboard 25. In step S12, the expansion start point is determined using all data on the heating temperature and stroke. This can be easily determined by sequentially determining the slope of the graph in FIG. 5 from low to high temperatures and determining point A where the slope is reversed. That is, when the sample contracts as it is heated, the contraction stops and it enters the equilibrium region, and then it begins to expand, the slope of the graph reverses, so it is sufficient to detect this point A. Next, the process proceeds to step S13, where the output signal Ss of the stroke meter 21 at the expansion start point and the corresponding heating temperature are stored.

[0012] In step S14, the expansion end point is determined. This can also be easily detected by sequentially finding the slope of the graph in FIG. 5 and finding the point B where the slope is almost zero. That is, the sample expands as it is heated, and it can be easily detected by finding point B, where the expansion has almost stopped and the slope of the graph has become almost zero. Next, the process proceeds to step S15, where the output signal Se of the stroke meter 21 at the end point of expansion and the corresponding heating temperature are stored. Then, in step S16, the expansion rate (%) is calculated using the following formula, and step S1
At step 7, the printer 23 records the expansion rate. Expansion rate = {
(Ss-Se) x cylinder area} x 100/(sample length x cylinder area)

As described above, according to this embodiment, the expansion start point and expansion end point are detected by a microcomputer, each piston stroke at the expansion start point and end point is read, and these values and the piston strokes inputted in advance are read. The expansion rate is determined using the above formula based on the cylinder area and sample length.

[0014] The expansion start and end points are visually determined from the graph of heating temperature and stroke shown in Fig. 5, which is recorded in parallel with the execution of the program, and the piston stroke at each point is read from the graph. , the expansion coefficient may be calculated using the above equation by determining the difference. It is also possible to visually read the expansion starting point from the graph and detect the expansion characteristics of the sample from the subsequent behavior of the graph. Furthermore, C
Only the expansion start point may be determined and output using the PU.

[0015]

[Effects of the Invention] According to the present invention, the stroke of the presser and the heating temperature accompanying the expansion of the sample are graphed, the expansion start point is detected from the graph, and the subsequent expansion characteristics are measured. , the expansion rate of rubber and food products can be easily and quantitatively measured.

[Brief explanation of the drawing]

[Figure 1] Flowchart showing an example of expansion rate calculation procedure

[Figure 2
] A diagram of the mechanical part of the device to which the expansion characteristic measuring method according to the present invention is applied.

[Fig. 3] A block diagram showing a control system of a device to which the expansion characteristic measuring method according to the present invention is applied.

[Figure 4] Flowchart showing an example of measurement procedure

[Figure 5] Graph of heating temperature and piston stroke

[Explanation of symbols]

1 Sample 10 Mechanism section 11 Cylinder 12 Heater 13 Piston 14 Load mechanism 21 Stroke meter 22 Temperature detector 30 Control circuit

Claims (1)

[Claims] Claim 1: Apply a constant load to a sample sealed in a sample chamber via a presser, heat the sample with the constant load, measure the stroke of the sample presser and the heating temperature, and calculate the difference between the stroke and the heating temperature. Along with recording the graph,
A method for measuring expansion characteristics, comprising: detecting a point at which the sample starts expanding based on the graph; and quantitatively detecting expansion characteristics of the sample after the expansion starts from the graph.