JPH0629843B2 - Lubricant performance evaluation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricant used for applying plastic working such as rolling and forging to a metal material, for example, a mandrel mill mandrel mill for rolling a seamless steel pipe. The present invention relates to a test device suitable for evaluating the quality of a lubricant used in.

(Prior Art) Conventionally, as a test device for evaluating the performance of a lubricant, a 4-ball tester, a Bowden tester, etc. are known.

Each of these is a device for evaluating a liquid lubricant as a lubricant. For example, as disclosed in Japanese Patent Laid-Open No. 58-41353, a lubricant is applied between two tools that are in contact with each other. It is supplied by spray, etc., and both tools are rotated or slid relative to each other, and the frictional force between the contact surfaces or contact points is measured to determine the magnitude, and the performance of the lubricant is evaluated. .

However, such a lubricant evaluation means cannot attain the object in the case where the object of the present invention is achieved.

(Problems to be Solved by the Invention) The present invention has been made to evaluate the properties of a lubricant that become solid during use. That is, recently, for example, in the rolling of seamless steel pipe, like a lubricant applied to a mandrel used in a mandrel mill, it is liquid before application, but by applying this to the mandrel and drying and fixing, The lubricant is in the form of a solid thin film on the surface of the mandrel, and in this state, there is a usage form of the lubricant used for rolling 7 to 8 continuous stands.

In such a case, the lubricant is not supplied again during rolling, and it is used in repeated rolling several times on the same mandrel. Is an important evaluation criterion.

If the performance of the lubricant is low, the load required for rolling increases, and the durability of the mandrel decreases, which greatly affects the manufacturing cost of seamless steel pipes.

Therefore, it is important to evaluate the quality of the lubricant in the above-described usage pattern, but the prior art described above cannot be evaluated for the following reasons.

That is, in the conventional device as described above, since the frictional force is measured while continuously supplying the lubricating oil, it is not possible to continuously supply the solid lubricant,
Therefore, even if the solid lubricant is applied, the lubricant disappears after one rotation or one slide, and continuous measurement cannot be performed. However, in actual rolling, part of the solid lubricant on the mandrel adheres to the rolled material side by rolling, and the lubricant remaining on the mandrel is used for rolling at the next stand.

Therefore, by evaluating the performance of the lubricant by applying pressure multiple times, it becomes possible to evaluate the durability of the lubricant in a state close to an actual phenomenon.

Further, in the conventional apparatus, since it does not cause a plastic deformation by merely applying a compressive force to the friction surface, it is basically different from the actual processing conditions and does not give a correct evaluation. .

The present invention has been made for the purpose of providing a lubricant performance evaluation device that solves the above-mentioned problems in the prior art.

(Means for Solving Problems) The conditions to be met as means for solving the problems in the prior art are that the lubricant does not disappear even when the tool is rotated or slid, and it is actually used. Since the lubricant can be evaluated under a deformation state close to, it is necessary to be able to evaluate it while performing plastic working. Since it is a test device, it must be a compact facility.

To satisfy the above conditions and to solve the technical problem in the present invention, the gist of the present invention is to rotate in the circumferential direction, have a tip shape smaller than that of a metal material test piece, and apply a lubricant. A cylindrical tool to be applied, a means for heating the metal material test piece to a temperature higher than that at the time of plastic working, and a cylindrical tool shaft between the cylindrical tool and the metal material test piece via a lubricant. Direction intermittently press contact several times,
And a pressing means for applying a pressing force to the cylindrical tool to cause a plastic material deformation in the metal material test piece to form a recess,
A lubricant performance evaluation device comprising means for detecting the rotational force of a cylindrical tool.

Hereinafter, the present invention will be described in detail based on an example thereof.

FIG. 1 shows an embodiment of the lubricant performance evaluation apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a cylindrical tool, which is rotationally driven by a motor 6 via gear devices 9-1 and 9-2. 2 is a heating furnace, which is a metal material (heating test piece)
3 is heated above the temperature at which it is plastically worked.

Reference numeral 4 denotes a lower table, on which a metal material (heating test piece) 3 is placed, and the metal material (heating test piece) is intermittently raised by a pressurizing means, in this embodiment, a hydraulic cylinder 5. )
In order to plastically deform 3 by the cylindrical tool 1, the metal material 3 is brought into pressure contact with the cylindrical tool 1. 7 is a post, and 8 is a hydraulic pump.

In this embodiment, the rotational force of the cylindrical tool 1 is measured by measuring the torque of the drive motor 6 or by attaching a strain gauge to the rotary shaft of the drive system of the cylindrical tool 1. .

(Operation) A lubricant is applied in advance to the tip of the cylindrical tool 1, and the cylindrical tool 1 is rotated by the drive motor 6. Heating furnace 2
The metal material (heating test piece) 3 extracted from the above is immediately placed on the lower table 4, the hydraulic cylinder (pressurizing means) 5 is operated, and the lower table 4 is raised, and the metal material 3 on the lower table 4 is cylindrical. The lower end of the tool 1 is intermittently brought into pressure contact.

The cylindrical tool 1 is pushed into the metal material 3 and, at the same time, the rotational force at that time is measured. The rotational force at this time is measured by a motor torque or a strain gauge attached to the rotary shaft of the rotary drive system of the cylindrical tool 1.

The magnitude of this rotational torque is converted into a friction coefficient, and the performance of the lubricant, particularly the durability, is evaluated by the magnitude thereof and by the change over time when intermittent rolling is performed a plurality of times.

The relationship between the rotational torque Tr and the friction coefficient μ is expressed by the following equation.

Here, p: pressure s: contact area μ: friction coefficient r: radius of a portion to which pressure is applied R: radius of contact surface p is constant in the contact surface between the cylindrical tool 1 and the metal material 3, that is, p = p = IP / S IP: Pushing force S: Total cross-sectional area, so μ is Given in.

Thus, it can be said that the smaller the time increment of Tr or μ, the better the lubricant.

Further, in the lubricant performance evaluation device of the present invention, the lubricant remains in the recess of the metal material (heating test piece) 3 generated when the cylindrical tool 1 is pushed, so that the cylindrical tool 1 rotates. Therefore, the performance of the lubricant can be evaluated as long as the temperature of the metal material 3 is maintained.

In the actual plastic working process, deformation is a phenomenon within 10 seconds, and a metal material with a wall thickness of about 10 mm (heating test piece)
If 3 is used, the temperature will not drop significantly,
Can be tested.

(Example) Using the apparatus of the present invention, the performance evaluation of two types of lubricants was performed.
It was performed under the repeated rolling reduction conditions. The result is the second
Shown in the figure.

As is clear from FIG. 2, the lubricant B has a drastic increase in Tr over time, and thus the lubricant A has better performance than the lubricant A. Recognize.

(Effects of the Invention) Since the present invention is configured and operated as described above, it is possible to evaluate the temporal change of the solid lubricant used for plastic working, that is, the durability, and to select the optimum lubricant. Has the effect of enabling selection and development of.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a lubricant performance evaluation device according to the present invention, and FIG. 2 is a performance evaluation of two types of lubricants using the device according to the present invention under three repeated rolling reduction conditions. It is a chart of the result when it is performed to. 1: Cylindrical tool, 2: Heating furnace 3: Metal material (heating test piece) 4: Lower table, 5: Pressurizing means 6: Motor, 7: Post 8: Hydraulic pump, 9-1, 9-2: Gear device

Claims (1)

[Claims] 1. A cylindrical tool which is rotationally driven in the circumferential direction and has a tip shape smaller than that of the metal material test piece, and is coated with a lubricant, and a metal material test piece having a temperature equal to or higher than a temperature at which it is plastically worked. Heating means, the cylindrical tool and the metal material test piece are intermittently pressure-contacted plural times in the axial direction of the cylindrical tool with a lubricant between them, and the metal material test piece is not plastically deformed. A lubricant performance evaluation device comprising: a pressurizing means for applying a pressing force for generating a depression to a cylindrical tool; and a means for detecting the rotational force of the cylindrical tool.