US2005306A

US2005306A - Method of making tubes

Info

Publication number: US2005306A
Application number: US731793A
Authority: US
Inventors: Clarence H Wallis
Original assignee: National Tube Co
Current assignee: National Tube Co
Priority date: 1934-06-21
Filing date: 1934-06-21
Publication date: 1935-06-18
Anticipated expiration: 1952-06-18

Description

June 18, c H. wA s ,METHOD OF MAKING TUBES Filed June 21, l 1934 Patented June 18, 1935 UNITED STATES 2,005,306 METHOD OF MAKING TUBES Clarence H. Wallis, Ellwood City, Pa., assignor to National-Tube Company, a. corporation of New Jersey 7 Application June 21, 1934, Serial no. 731,793

4 Claims.

This invention is a method of making seamless steel tubes with clean inside surfaces.

Such tubes are nowmade by hot and cold working the metal to tubes of the gage desired. These tubes are then annealed, after which their inside surfaces are washed and dried with great care and their opposite ends solidly pointed in an effort to keep these surfaces clean. The tubes are then externally coated with lubricant, sunk to the proper outside diameters by being drawn through i a die, this including annealing and pickling as required, are finally annealed to obtain the p y ical characteristics desired, and are finished. Finishing includes straightening and cutting to length, the cutting removing the tubes solidly pointed ends.

Every precaution is taken to prevent the inside surfaces of the tubes from being contaminated by the lubricant after they have been washed clean upon the completion of their final drawing. The solid pointing of their ends is intended to exclude the lubricant and to protect their inside surfaces from dirt and the action of the oxygen in the air. However, trouble is experienced in that the drying of their inside surfaces cannot be done quickly enough, after they have been cleaned by washing, to prevent the formation of rust. Furthermore, some air is necessarily entrapped during the solid pointing of their ends, and this air oxidizes their inside surfaces during the subsequent annealing operations.

Referring to the accompanying drawing:

Figure 1 illustrates a tube.

Figure 2 shows this tube after its ends have been pointed.

Figure 3 shows the removal of the pointed ends of this tube.

According to the present invention, lubricant is used on the last cold drawing pass of the tubes over a mandrel, which is characterized in that it will not deposit a residue when heated to annealing temperatures. Such a lubricant may be a soap-tallow lubricant which is substituted for the fiour-tallow lubricant customarily used. Specifically speaking, such a lubricant may consist of approximately ten per cent soap stock and eight per cent tallow substitute, mixed with eighty-two per cent water. The tallow substitute contains heavy mineral oil and degras.

After the tubes have received their last cold drawing pass, their opposite ends are solidly pointed with the described lubricant still on their inside surfaces. That is to say, their inside surfaces are not cleaned. The solidly pointed tubes are then' annealed to remove the stresses created by this cold working, and it is particularly at this stage that the advantages of the lubricant come into play. Thus, because of its described characteristic, it does not deposit a residue upon the inside surfaces of the tubes but is instead oxidized to a fine, nonadhesive powder. Furthermore, since the lubricant is oxidized by the air entrapped in these tubes, the oxygen content in this air is removed.

It is consequently obvious that the tubes inside surfaces do not become oxidized, and that they can be finished simply by cutting off their solidly pointed ends, the usual straightening operation being, of course, included. The tubes then have perfectly clean inside surfaces.

Usually the tubes must be sunk to smaller outside diameters. When this is done, the solidly pointed and annealed tubes are pickled and washed in the usual manner, it being noted that this does not affect their inside surfaces because their pointed ends exclude all fluids. They are then doped with lubricant and sunk to the required outside diameters by one or more passes with intermediate annealing and pickling, as required, after which they are given a final anneal for the purposes of imparting the desired physical characteristics, straightened, and their pointed ends removed.

In the drawing, Figure 1 shows a tube l as it appears when ready for pointing, Figure 2 shows the tube I with its ends pointed, as at 2,. so as to close its inside. Figure 3 shows the removal of the pointed ends by means of saws 3.

vThe specific details connected with these various stages have already been described.

It is to be noted that the method is not only better than the standard practice, in that it produces pipes with cleaner inside surfaces, but that it is quicker in that the careful washing and drying steps are eliminated. The flour-tallow lubricant usually used cannot be utilized in the final drawing stage of the new process because it deposits a residue when heated to annealing temperatures. Soap-tallow, on the other hand, does not deposit such a residue and, in addition absorbs the oxygen in the air entrapped by the solid" pointing of the tubes so that this ordinarily objectionable atmosphere becomes essentially reducing in character whereby the inside surfaces of the tubes are protected.

I claim:

1. A method of making seamless tubes with clean inside surfaces, including using a lubricant on their last cold drawing passes over a mandrel,

which will not deposit a residue when heated to posite ends of said tubes after said last cold drawing passes without cleaning their inside surfaces, subsequently annealing said tubes and then finishing said tubes including cutting 01! their solid- 1y pointed ends.

2. A method of making seamless tubes with clean inside surfaces, including using a. lubricant on their last cold drawing passes over a mandrel, which will not deposit a residue when heated to annealing temperatures, solidly pointing the opposite ends of said tubes after said last cold drawing passes without cleaning their inside surfaces, subsequently annealing said tubes, then sinking said tubes to the required outside diameters and finishing said tubes including cutting oil their solidly pointed ends.

3. A method of making seamless tubes with clean inside surfaces, including using a soap- 2,005,306 annealing tempeatures, solidly pointing the optallow lubricant on their last cold drawing passes over a mandrel, solidly pointing the opposite ends of said tubes after said last cold drawing passes without cleaning their inside surfaces, subsequently annealing said tubes and then finishing said tubes including cutting off their solidly pointed ends.

4. A method of making seamless tubes with clean inside surfaces, including using a soaptallow lubricant on their last cold drawing passes over a mandrel, solidly pointing the opposite ends of said tubes after said last cold drawing passes without cleaning their inside surfaces, subsequently annealing said tubes, then sinking said tubes to the required outside diameters and finishing said tubes including cutting ofi their solid- 1y pointed ends.

CLARENCE H. WALLIS