JPH0373816B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for evaluating lubricants, and more particularly to improvements in a method and apparatus for evaluating the frictional properties of lubricants. There are two types of friction between solid bodies in which a lubricant is used: sliding friction and rolling friction.The frictional properties of a lubricant are those caused when two solid bodies contact each other under a certain load and undergo sliding motion, or rolling friction. It refers to various characteristics that occur during movement, sliding and rolling movement, such as the force that occurs on contact surfaces that impedes movement (frictional force), the degree of wear on the solid surface, load-bearing capacity, and the fatigue life of the solid. ,
This is one of the important basic properties of lubricants. Friction in actual machines almost always includes an element of rolling friction, so in order to perform an evaluation that correlates with the actual machine, it is desirable to be able to evaluate rolling friction as well. Conventionally, a two-cylinder test (eg, SAE test) is known as a method for evaluating rolling friction characteristics. However, this method has drawbacks such as difficult and expensive production of test pieces (cylinders) and complicated and time-consuming testing methods. On the other hand, among the rolling friction characteristics, the Japanese Industrial Standards (JIS) is a method for easily evaluating the fatigue life of solids.
An improved rolling four-ball test is known, which is an improvement on the four-ball test specified in . In other words, in the normal four-ball test, four steel balls of the same diameter are piled up in a pyramid shape, the bottom three balls are fixed, and the top one is rotated while a load is applied to evaluate the sliding friction characteristics. However, in the improved rolling four-ball test, the bottom three balls are not fixed and are allowed to rotate freely, and by rotating the top one, the bottom three balls also rotate. However, even with this improved rolling and walking ball test, a sufficient correlation with the actual machine was not necessarily obtained. Various factors can be considered as the reason for the poor correlation with the actual machine, but one major factor is that regardless of the metal material of the actual machine, All four steel balls are steel balls with metal material, size, and surface condition that comply with JIS, ASTM, etc. regulations. This is JIS,
Although it is easy to obtain steel balls that meet ASTM regulations, it is extremely difficult for those trying to evaluate lubricants to accurately process any metal material into a spherical shape. be. An object of the present invention is to provide a method and apparatus for evaluating the frictional properties of a lubricant that are highly correlated with actual equipment. This also introduces the element of rolling friction if necessary. That is, the evaluation method and evaluation device according to the present invention can easily process the top one of the four steel balls in the four-ball test and the improved rolling four-ball test from any metal material suitable for the actual machine. The structure corresponds to the case where the test piece is changed to a shape that can be changed. In the evaluation method according to the present invention, three steel balls having the same diameter are arranged in an equilateral triangle shape in a sample container containing lubricant, and a test piece having a conical outer peripheral surface on the tip side is The three steel balls are arranged so that the outer circumferential surfaces are in contact with each other simultaneously in the lubricant, and the test piece is rotated while applying a predetermined load between the test piece and the steel balls. The objective is to be achieved by measuring the rotational torque generated between the piece and the sample container, and when introducing a rolling friction element, the method described in 3.
A steel ball is made rotatable in a sample container, and when only the sliding friction characteristics are to be evaluated, the steel balls are fixed in the sample container. Further, the evaluation device according to the present invention has a sample container into which a lubricant is placed, three steel balls arranged in an equilateral triangle shape in the sample container, and a conical outer peripheral surface on the tip side. a test piece arranged such that its outer peripheral surface contacts the three steel balls simultaneously in a lubricant; a pressurizing mechanism that applies a predetermined load between the test piece and the steel balls; The above objective is achieved by providing a rotational drive mechanism for relatively rotating the test piece and the sample container, and further providing a torque measurement mechanism for measuring the rotational torque generated between the test piece and the sample container, if necessary. When introducing a rolling friction element, the three steel balls are rotatably arranged in the sample container, and when only the sliding friction characteristics are to be evaluated, the steel balls are fixed to the sample container. It is something. Embodiments of the present invention will be described below based on the drawings. FIG. 1 shows a first embodiment of the lubricant evaluation apparatus according to the present invention.
is buried, and three steel balls 3 are arranged in an equilateral triangular shape on the bottom surface 1A through the seat plate 2, and these three steel balls 3 are connected to the bottom surface 1A through bolts 4.
It is positioned by a spacer 5 fixed to A, and is rotatable within the sample container 1. The outer circumferential surface 6A of the test piece 6 is formed with a conical outer circumferential surface 6A having a predetermined apex angle on the tip side at the center of the three steel balls 3 arranged in the shape of an equilateral triangle. It is arranged so as to contact each of the three steel balls 3 at the same time. Note that even if the test piece 6 contacts the steel ball 3 by pressing the steel ball 3 against the bottom surface 1A, the steel ball 3 will not protrude from the sample container 1 due to the spacer 5 or float from the bottom surface 1A. It is designed so that it is always placed in an appropriate state without moving up or down. The size of the apex angle of the tip of the test piece 6 is the outer peripheral surface 6A.
is not particularly limited as long as it has a conical shape, but it stabilizes the position of the steel ball 3 and improves the outer peripheral surface 6A.
In order to make the contact position between the steel ball 3 and the steel ball 3 appropriate, it is usually 30 to 150 degrees, preferably 45 to 135 degrees. If the apex angle is large, the load at the contact point between the outer circumferential surface 6A and the steel ball 3 will be large, and if the apex angle is small, the load will be small. In addition, the outer peripheral surface 6A
A metal rod made of any metal material selected according to the actual machine can be easily manufactured using a lathe or the like. Further, a predetermined amount of lubricant 7 is placed in the sample container 1, and the test piece 6 and steel balls 3 are
It is now possible to contact people inside. The base end of the test piece 6 is connected to a vertical shaft 9 as a rotational drive mechanism via a drill chuck 8, and the outer peripheral surface 6A of the test piece 6 rotates while making point contact with each of the three steel balls 3. It is configured so that it can be used. A torsion rod 12 is connected to the center of the lower end surface of the sample container 1 via a spline bearing 11 so as to be non-rotatable but movable up and down, and the lower end side (not shown) of this torsion rod 12 is non-rotatable but movable up and down. The torsion rod 12 is configured such that a predetermined amount of rotational torque can be applied to the sample container 1. In addition, the sample container 1 has a lifting platform 1 as a pressurizing mechanism.
The test piece 6 is supported on the steel ball 3, and the elevating table 13 is configured to apply a predetermined load between the test piece 6 and the steel ball 3. Furthermore, this lifting platform 13
The upper end of the sample container 1 is rotatable together with the sample container 1. Further, a sample container 1 is provided on the outer peripheral surface of the sample container 1.
A cylindrical scale plate 14 indicating the amount of rotation is fixed,
A pointer 15 is provided near the scale plate 14 to indicate the scale plate 14.
4 and the pointer 15 constitute a torque measuring mechanism 16 that indicates the rotational torque of the sample container 1. Next, the operation of this embodiment will be explained. While applying a predetermined load between the test piece 6 and the three steel balls 3 using the lift table 13 as a pressure mechanism, the test piece 6 is placed in the lubricant 7 using the vertical shaft 9 as a rotational drive mechanism. The steel ball 3 is rotated so that the outer peripheral surface 6A and the steel ball 3 are in contact with each other. Outer surface 6A
A lubricant film of the lubricant 7 is formed between the steel ball 3 and the steel ball 3, and a frictional force that impedes this rotation is generated, and this frictional force generates a rotational torque in the sample container 1 in the rotational direction of the test piece 6. do. This rotational torque is displayed by the torque measuring mechanism 16 at a position where it is balanced with the rotational torque of the torsion rod 12 in the opposite direction, and the lubricant 7 This will result in an evaluation of This embodiment has the following effects. Since the configuration uses test piece 6 instead of the one ball used in the conventional four-ball test and the improved rolling four-ball test, the various advantages inherent in the four-ball test and the improved rolling four-ball test, such as ease of operation, can be achieved. in,
While having the advantages of easily obtaining a high load, using a small amount of sample, and reducing testing costs, the outer circumferential surface 6A of the test piece 6 can be processed extremely easily using a lathe or the like. Any metal material can be used to match the actual machine. Therefore, it is possible to provide a correlation with the actual machine in terms of the metal material, and the obtained evaluation results have the effect of being highly useful. Moreover, when processing the outer circumferential surface 6A of the test piece 6, it is easy to create a surface condition that matches the actual machine, and by appropriately selecting the size of the apex angle, the contact point with the steel ball 3 can be made to match the actual machine. It is possible to select test conditions that suit the test conditions, and from these points as well, there is an effect that the correlation with the actual machine can be improved. Next, the present invention will be explained in more detail using the following experimental examples. Experimental Example 1 Using the apparatus shown in Fig. 1, four types of commercially available stainless steel rolling oils (A oil, A oil,
Let's call them B oil, C oil, and D oil. Both have a viscosity of 15 cst at 40°C. ) was evaluated under the following conditions. Test piece 6…Material stainless steel (SUS430), apex angle
90 degrees Rotation speed of test piece 6...500rpm Steel ball 3...3/4 inch SUJ-2 for JIS K-2519 Load...243Kg Oil temperature...50℃ Measurement method...Rotational torque acting on sample container 1 is measured by load cell-like torque Measurement was performed using the measuring mechanism 16. The evaluation results obtained under the above conditions are shown in Table 1. Next, in order to see the correlation with actual equipment, the performance of each of the oils A to D was examined in actual equipment under the following conditions. Rolling machine: 4Hi rolling machine with a work roll diameter of 40 mm and a back-up roll diameter of 136 mm.Rolled material: The material is the same as test piece 6 in the above experimental example, and the method of rolling a 50 mm wide coil of stainless steel (SUS-430): Rolling speed: 130 m/min , Tension (same before and after) 350Kg, 4-pass rolling from 1.5 to 0.35 mm, rolling reduction rate: 37.5 → 30.5 → 27.5 → 26.0% Rolling force calculation method: The maximum rolling force for each pass was averaged. Table 1 shows the results obtained using an actual machine under the above conditions.

[Table] From Table 1, the correlation coefficient between the evaluation results according to the present invention and the actual performance on the actual machine is 0.97 (90% significant).
Therefore, it can be seen that the rolling reduction force (rollability) in an actual machine can be accurately predicted by the evaluation method according to the present invention. Experimental Example 2 Four types of commercially available aluminum foil rolling oils were used as lubricant 7 (all are products of the same company, and oil E, oil F, and G
Oil, H oil. In both cases, the viscosity at 40℃ is
It is 1.5 cst. ) was evaluated under the following conditions. Test piece 6...Material aluminum (1050 material), apex angle
90 degrees Rotation speed of test piece 6...500rpm Steel ball 3...3/4 inch SUJ-2 for JIS K-2519 Load...42Kg Oil temperature...50℃ Evaluation method...Rotational torque acting on sample container 1 is measured by load cell-like torque Measurement was performed using the measurement mechanism 16. The evaluation results obtained under the above conditions are shown in Table 2. Further, in Table 2, the ranking of the maximum rolling speed in aluminum foil rolling, which was displayed for oils E to H, is shown as 1, 2, 3, and 4 in descending order.

【table】

Table 2 also shows that according to the present invention, the maximum rolling speed in aluminum foil rolling can be accurately predicted. In the first embodiment described above, the steel balls 3 were rotatably arranged in the sample container 1, but as in the second embodiment shown in FIG. may be fixed to the sample container 1 with a ball holder 20. In this case, the elements of rolling friction characteristics are not introduced, and only the sliding friction characteristics are evaluated. In addition, although the lubricant 7 is evaluated by measuring the rotational torque of the sample container 1, the present invention is not limited to this, and evaluation may be made by measuring, for example, the maximum load value or maximum rotational speed that does not cause seizure. Alternatively, the wear resistance of the lubricant 7 may be evaluated by measuring the wear marks on the steel balls 3 and the test piece 6. Furthermore, by changing the metal material of the test piece 6 variously for the same lubricant 7, it is also possible to evaluate the characteristics of the metal material. Further, the shape of the outer circumferential surface 6A on the tip side of the test piece 6 is not limited to that shown in FIG. 1, but may be in the shape of a truncated cone as shown in FIG. 3. As described above, according to the present invention, it is possible to provide a lubricant evaluation method and evaluation device that are highly correlated with actual equipment.

[Brief explanation of drawings]

FIG. 1 shows a first diagram of a lubricant evaluation device according to the present invention.
FIG. 2 is a sectional view showing the main parts of the second embodiment, and FIG. 3 is a front view showing the tip shape of a test piece other than the above embodiment. 1... Sample container, 3... Steel ball, 6... Test piece,
6A...Outer peripheral surface, 7...Lubricant, 9...Vertical shaft as rotational drive mechanism, 12...Torsion rod, 13...
Lifting platform as a pressurizing mechanism, 16... Torque measuring mechanism.

Claims (1)

[Claims] 1. Three steel balls having the same diameter are arranged in an equilateral triangular shape in a sample container containing a lubricant, and a test piece having a conical outer peripheral surface on the tip side,
The method is characterized in that the three steel balls are arranged so that the outer circumferential surface contacts each of the three steel balls at the same time in a lubricant, and the test piece is rotated while applying a predetermined load between the test piece and the steel balls. Evaluation method for lubricants. 2. A sample container into which a lubricant is placed, three steel balls arranged in an equilateral triangle shape in the sample container, and a conical outer circumferential surface on the tip side, and the outer circumferential surface is formed of the three steel balls. A test piece arranged to simultaneously contact a ball in a lubricant, a pressure mechanism that applies a predetermined load between the test piece and the steel ball, and a rotational drive mechanism that rotates the test piece. A lubricant evaluation device characterized by: 3. The lubricant evaluation device according to claim 2, wherein the three steel balls are rotatably arranged within a sample container.