DE2501083B2 - Process for setting, mutually identical friction properties and the same abrasion behavior in gray cast iron batches - Google Patents

Description

description

From US-PS 2179 695 it is known to improve the wear resistance of cast iron by 0.05 to 0.60% titanium pi.

In "High quality cast iron (gray cast iron)," by E Piwowarsky, 2nd edition, 1951, page 780, the Manufacture of brake drums from alloyed gray cast iron, the titanium, vanadium and niobium in quantities of not may contain more than 0.15%.

The problem has hitherto occurred in the manufacture of brake drums and brake disks from gray cast iron on that the braking properties could change significantly from batch to batch, which of course was dangerous if brake disks or drums were used on a motor vehicle came from different Gnugußrfirgen. Man previously led the different braking properties of discs ramming from different batches on a different structure of the gray cast iron.

The invention has set itself the task of creating a method when it is carried out it is possible to have the same friction properties and the same abrasion behavior in gray cast iron batches set in order to avoid the disadvantages described above.

According to the invention, this object is achieved by the> characterizing part of the patent claim.

The invention is based accordingly a-if the knowledge, that coefficient of friction, abrasion and wear behavior of gray cast iron, which is especially used as a material for Manufacture of brake disks and brake drums used is reproducible can, if the elements contained in the material titanium, vanadium and niobium on one of the to Achieving properties functionally dependent, so to be specified value, the maximum 0.15% for each of these elements or their total amount is set. It is this value that is responsible for According to this value, brake disks and brake drums are characteristic of the braking behavior the brake discs or drums are mated, d. H. be divided into classes so that one at one vehicle can use brake discs of different production together. Setting the total amount of Tita.;, Vanadi um and / or niobium to values below 0.015% ensures that the friction and abrasion properties of the unalloyed gray cast iron are reproducible at the upper end of the range, the normally exists for such a material. One

; 5 Controlling the total content of these elements to more than 0.075% ensures that the friction and the Abrasions are reproducible at the lower end of the range, which is normally each individual Material is received The upper limit is more normal wise below the salary, the larger structure would cause changes in the unalloyed gray cast iron.

The content of the elements mentioned can be determined by known metallurgical methods.

For example, the titanium content can be spectrographically performed during a standard quality control test of the melt, e.g. B. when the Silicon content is determined in order to determine the cooling properties of gray cast iron.

Titanium as well as vanadium and niobium form hard and high-melting carbides (or complexes thereof) which are in the form of hard discrete particles in the gray cast iron. The content of this Elements can be added to the

si gray cast iron can be set. For example, the titanium content can be increased by adding titanium in the form of ferrotitanium to the melt. Vanadium can be added to a cast iron melt in the form of ferrovanadium.

The examples given in the following table generally explain preferred embodiments of the Invention. In the table, the rest of up to 100% of the gray cast iron materials are of course iron. the Examples 5 and 7 illustrate the effect achieved by Dispensing a controlled amount of vanadium to the Cast iron from example t is obtained. Example 3 shows the effect of adding a controlled amount of titanium to the cast iron of Example 2 (these controlled amounts are added according to metallurgi see standard methods). The remaining examples can be used to explain the effect of gradually increasing titanium content in a controlled manner in various cast iron materials be used.

Composition (%) example 2 3 4th 5 6th 7th 8th 9 and properties I. 3.32 3.28 3.42 3.20 3.60 3.20 3.32 3.30 carbon 3.20 1.77 1.95 2.23 2.15 2.00 2.15 1.77 2.10 Silicon 2.15 0.56 0.81 0.60 0.62 0.75 0.62 0.56 0.65 manganese 0.62 0.07 0.03 0.103 0.06 0.035 0.06 0.07 0.03 sulfur 0.06 0.11 0.058 0.06 0.075 0.010 0.075 0.11 1.30 phosphorus 0.075 0.014 0.018 0.029 0.012 0.053 0.012 0.092 0.107 titanium 0.012 - - - 0.027 - 0.048 _ _ Vanadium _

3 example
1 2 25 01 083 5 6th 4th 7th 8th 9 continuation 0.48
0.55
0.03 0.53
0.65
0.05 0.38
0.31
0.02 0.41
0.24
0.01 0.34
0.28
0.01 0.38
0.21
0.005 0.38
0.19
0.01 Composition (%)
and properties - 0.52
0.89
0.06 3 4th 0.48
0.96
0.05 0.40
0.66
0.03 0.38
0.81
0.04 - 0.39
0.48
0.01 Friction (material A)
Material abrasion (material
Disc abrasion (material A)
A) 0.43
0.40
0.02 0.40
0.28
0.01 Friction (material B)
Material abrasion (material
Disc abrasion (material B)
B) 0.48
0.60
0.05 0.44
0.93
0.05

Material abrasion = loss of thickness of each disc brake pad in mm. Disc abrasion = total loss in thickness of each disc in mm.

The table shows the effects that are achieved when brake discs are made of cast iron are produced, as opposed to one or two types of disc brake pads, hereinafter referred to as material A and material B denote wt-rden, be tested with standard quality (commercially available). The test method is described in more detail below.

Test method

Known disc brake pads are installed with full size in a conventional brake, using the correspondingly dimensioned discs. An inertia dynamometer mi * 294 kg / m ^{2 is} used. A new set of brake pads is used to carry out each test, the disks being freshly ground before each test.

The test includes seven temperature-controlled circuits, each with 200 brake applications during one Time span of 3 hours, which should simulate typical road conditions in a passenger car. the Speed when applying the brake, when releasing the brake, the pressure and the temperature are adhered to in arbitrary but reproducible sequences so that an energy spectrum is obtained that is representative of different degrees of stress that are associated with normal use occur from passenger cars on roads.

The 7 circuits include two circuits which enable light-duty running should simulate, two circuits simulate a moderate load and two circuits simulate one heavy duty, followed by a circuit for moderate use. The temperatures are controlled in such a way that the following areas are detected:

Low stress
average

Moderate use
average

Heavy use
average

70-140 ⁰ C.
100 ⁰ C

90-210 ⁰ C.
150 ⁰ C

150-300 ⁰ C.
2I0 ° C

The friction is measured with each braking and automatically plotted as a function of the temperature. The values ste "obtained in carrying out the examples en represents the average Reioung. Which is determined at 150 ⁰ C in the case of the final circuit for a moderate use.

Each brake pad is measured at 4 points using a digital micrometer that points to 0.0025 mm can be read. The discs are measured with a similar micrometer at 16 points that are round around the disc at a distance of 19 mm from that of the outer periphery. The in the implementation of the examples obtained are the total thickness losses that occurred during the full 7 shifts appear.

The results can be summarized in the form of graphs which are represented by the figures. It shows
F i g. 1 a graphical representation of the coefficient of friction

J5 efficient, which depends on the content of the Metal is applied, which forms hard and refractory discrete particles,

2 shows a graphic representation of the friction material wear, which depends on the fwatall salary is recorded

3 shows a graphic representation of the disc (cast iron) abrasion which is plotted as a function of the metal
It can be seen that by controlling the titanium plus vanadium (or any other material or mixed metal system) content to within the range of 0-a, high coefficients of friction (and a high rate of wear) are achieved. By controlling the titanium content to a value between b - b} , low coefficients of friction (and a low abrasion speed) are achieved. It is of course possible to regulate the content of titanium or similar melali to a value within the range a- b in order to achieve an intermediate coefficient of friction, but the steepness of the curve in that range usually means that the degree of control the frictional properties is not so exact. The positions of a and b vary depending on the

bo friction means used. In the case of material A, a is 0.015% titanium and b is 0.04%, while in the case of material B, a is 0.02% titanium and b is 0.065%. It is clear from the graphs that the invention provides for the first time the possibility of precise control of the frictional properties of cast iron, so that a method is made available which enables reproducibility of these properties of cast iron.

sencharge to cast iron charge guaranteed. With the invention it is now possible to make differences Avoid that with regard to the properties of counter components in a vehicle or in occur in different vehicles of a certain type, namely by ensuring that the content of titanium or a similar metal in the cast iron charge is maintained at a desired level, the level being reduced if necessary to the desired value is set. The content of titanium or a similar metal, as above has been described, but a decrease in the content is difficult in a foundry to accomplish, since a dilution of the base iron material with a ferrous material is required which has a low content of a having such metal.

Other commercially available friction materials give results that are comparable to those which are obtained in the case of the commercially available friction materials described above.

1 sheet of drawings

Claims (1)

Patent claims: 1. A method for setting mutually identical friction properties and the same abrasion behavior in gray cast iron batches, characterized in that the titanium content, Vanadium and niobium is set individually or together to a predetermined value, the is 0.15% or less 2 Use of a gray cast iron produced according to claim 1 as a material for the production of Brake drums and brake discs.