Thread Rolling Research Articles

Effect of the degree of filling of the thread contour and heat treatment on residual stresses in threaded components

1. Thread rolling leads to the formation of high compressive residual stresses in the surface layer of the root. 2. The distribution of the residual stresses in the thread in the bolts and studs rolled with the open contour is more favorable than in thread rolling using the closed contour. 3. Heat treatment of the rolled threaded components causes relaxation and redistribution of the compressive residual stresses. This also explains the reduction of their fatigue resistance. 4. The reduction of the radius of the thread root increases the residual stresses in thread rolling thus compensating the reduction of fatigue resistance caused by the increase of the concentration of working stresses. 5. The residual stresses in the threaded components correlate with the fatigue resistance characteristics of these components, i.e., the bolts and studs with a higher level of the compressive residual stresses are characterized by high fatigue resistance. Knowing the level and distribution of the residual stresses, we can predict the fatigue resistance and issue recommendations for the selection of the optimum process of manufacture of threaded components.

MUELLER ALLOY 3602

Abstract MUELLER Alloy 3602 is a leaded brass of moderate strength and ductility. It is suitable for moderate thread rolling. Also, because of its free-cutting characteristics, it is suitable for high-speed screw-machine products. Among its many applications are hardware, unions, bolts, screws and nuts. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Cu-489. Producer or source: Mueller Brass Company.

CARPENTER STAINLESS 302HQ-FM

Abstract CARPENTER STAINLESS 302HQ-FM, a modification of Carpenter Stainless Custom Flo 302HQ, has excellent cold headability plus machinability approaching that of AISI Type 303 stainless steel. It is designed primarily for cold-headed parts that are to be drilled, slotted, broached, etc; in addition, it can be used in bar form on automatic screw machines on parts where thread rolling or cold form tapping operations are critical. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-432. Producer or source: Carpenter.

Thread rolling— a neglected art

Thread rolling is a generally accepted alternative to cutting for the production of small threaded piece parts such as BA screws and self-tappers. Yet the wider uses of thread rolling have been neglected by production engineers over the years.In this article, Walter H Froehlich describes how the modern two-roll thread rolling machine can produce practically any thread form, including serrations and knurls, in a wide range of sizes on such items as valve stems, lead and ball screws, worms and taps.

高強度ボルトの疲れ強さ向上について

It has been said that the fatigue strength of high strength bolts does not increase in proportion to the statical tensile strength. In order to establish the stable method for the improvement of fatigue strength of high strength bolts, the large scale experiments are done, referring to the published papers. The six factors including the pitch modification and the sequence of thread finishing are taken, and the design of experiment is based on the orthogonal array L32 (231). As the method of fatigue testing, the staircase method with small samples is used. The obtained conclusions are as follows : (1) In the range of the present experiments, the effects of nominal diameter and pitch of screw threads are not significant, and the effects of pitch modification, strength grade (D), sequence of thread finishing and mean stress in fatigue testing (G) as well as the interaction between D and G are significant. (2) The slight reducing (-0.3%) of the pitch of bolt threads comparing with that of nut threads and the thread rolling after heat treatment are effective to improve the fatigue strength of high strength bolts, and especially, the use of both actions has an excellent effect.

Rolling of inside threads in plastic materials

Rolling of inside threads in plastic materials

Salt Water and Hydrogen Sulfide Corrosion Fatigue of Work-Hardened, Threaded Elements

Abstract This work describes the results of a laboratory testing program undertaken to evaluate the merits of work-hardened, threaded machine elements when subjected to axial fatigue in the presence of a corrosive environment. The experimental apparatus is described, including details of the corrosive mediums. The most damaging corrosive medium consisted of a salt water solution through which hydrogen sulfide gas was bubbled. Lower corrosion fatigue damage was noted for aerated salt water and the least occurred for a deaerated salt water solution. The corrosion fatigue results are compared with results obtained in air for simple cut threads and fully cold-worked or rolled threads formed on AISI 8635 steel. The results show that at a life of 105 cycles the fully cold-worked threaded element had an endurance stress of 74 ksi (510 MPa) compared with 44 ksi (303 MPa) for the simple cut threaded element. Under the combined action of corrosion fatigue in the presence of a hydrogen sulfide saline solution these values were reduced to 46 ksi (317 MPa) and less than 20 ksi (138 MPa), respectively, which indicated that the fully cold-worked, threaded element was superior to all thread forms evaluated under a variety of environmental conditions.

Cold Forming and Extrusion of Steel

AbstractThe general terms ‘cold forging’ or ‘cold forming’ are applied to operations in which established processes, such as extrusion, upsetting (heading), drawing, ironing, sinking, coining, swaging, expanding, and thread and form rolling, are combined in a predetermined sequence. The technique is used for the manufacture of a wide range of light engineering components, such as gudgeon pins, spark-plug bodies, drive shafts, flanges, ball-race, casings, socket spanners, assorted cylinders, and toothed and splined parts.

Effect of notch burnishing and thread rolling on the fatigue strength of specimens of titanium alloys VTZ-1 and VT16

Effect of notch burnishing and thread rolling on the fatigue strength of specimens of titanium alloys VTZ-1 and VT16

Study on the Effects of Cold - and Warm - Thread Rolling on the Delayed Fracture Strength

Delayed fracture strength of screws warm-and cold-thread-rolled after heat treatment to high strength levels was investigated in corrosive atmospheres.Screws thread-rolled after hear treatment did not show decrease of delayed fracture strength at high stress levels, unlike ones heat treated after thread-rolling.This feature was recognized in severe atmosphere containing H2S gas, moreover those were found to have several to ten times longer life than these.Screws made by warm-thread-rolling which decreases wearing of die and power of forming showed the similar effect of improving delayed fracture strength as cold-thread-rolled ones.

Fatigue of Threaded Sucker-Rod Couplings

Abstract Accelerated laboratory tests on the fatigue characteristics of sucker-rod couplings were carried out on a closed-loop hydraulic testing system. The purpose was to evaluate a number of different thread designs currently being used in the manufacture of sucker-rod couplings. The thread forms tested included the simple cut, a keyhole cut and burnished, cut and cold worked and fully cold worked. The results show that the fatigue life increases as the degree of cold-working increases. It is also seen that the effects of accelerating the testing are insignificant. Introduction THE FAILURE OF SUCKER-ROD JOINTS is of considerable interest to those involved in petroleum production. To eliminate or minimize such failures many attempts have been made both in producing new rod and coupling designs and eliminating the coupling altogether. The literature shows a number of papers dealing with the subject of joint failures, specifically related to improving the pin connection. There is apparently very little written on the coupling itself, but there are a multitude of coupling designs commercially available for use in joining sucker-rods. The question arises as to which of these designs is the best. Thus, to aid in the design and selection of a coupling, the purpose of this paper is to evaluate the fatigue life of a number of different thread designs which are being used in the manufacture of sucker-rod couplings. Coupling design has, for the most part, been consistent with the pin design to which it must mate. Coupling thread design has evolved from the simple cut thread, to a keyhole, burnished, cut and cold worked, and recently to a fully cold worked or rolled thread. Apart from the simple cut thread and keyhole thread, all other thread designs incorporate some degree of cold working in the thread-forming process. To the consumer the coupling represents but a part of the cost of a rod. However, to the manufacturer, not all coupling designs can be made with the same ease and quality control and, hence, same cost. The majority of coupling failures are the result of fatigue damage. This damage can be accelerated by improper joint make-up in the field, operating in a hostile environment such as sour wells, manufacturing couplings from materials with poor fatigue characteristics, and the manner in which the thread has been formed inside the coupling. The problems of improper joint make-up have been explored in the paper by Hardy(1). In this same work, reference is made to the influence of corrosion on the fatigue life of sucker-rod materials. Although the scope of the present investigation excludes evaluation of the fatigue life of coupling materials, its main purpose is to evaluate the fatigue life of thread designs found in sucker-rod couplings and compare these results with the fatigue life of the unnotched coupling material. Testing Program In any testing program involving fatigue, one of the two major problems to be overcome is to control all but one of the variables involved.

DOUBLE SIX SUPER

Abstract Double Six Super is a high-carbon high-chromium air hardening tool steel having excellent non-deforming characteristics. It is recommended for blanking and thread rolling dies, drawing and coining dies, gauges and mandrels. This datasheet provides information on composition, hardness, tensile properties, and compressive strength as well as fracture toughness. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-205. Producer or source: Edgar Allen & Company Ltd, Imperial Steel Works.

金属表面にV形溝を切りくず無しにつける過程について (第1報)

The process of forming of a single groove by a rigid body is considered as a simplified model for the deformations that occur in thread rolling, knurling, chipless ruling, grinding and processes of friction and wear.In the first report, plane strain indentation by a wedge- and semi-plane strain indentation by an abacus' bead-shaped rigid body on to the surface of a semi-infinite rigid-perfect plastic body are analyzed using the energy method. The indentation force and piled up shape of the specimen surface are obtained. They are compared with experimental results obtained for cold-rolled copper plates and show a good coincidence.

RED STAR TUNGSTEN

Abstract Red Star Tungsten is a high-carbon low-alloy tool steel having high hardness, good toughness, and keen cutting edge. It is recommended for cutting tools, thread rolling dies, paper knives, etc. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as deformation. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-173. Producer or source: Vanadium Alloys Steel Company.

ねじ転造ダイスのねじ山公差について

The accuracy of produced thread in thread rolling is mainly determined by the tolerances for the blank diameter and the thread profile of rolling dies. The tolerance for the thread profile of rolling dies must be specified taking into account its relation to the tolerance for the blank diameter. In this investigation the relationship between them is discussed, and the draft of the Japanese standard (JIS), the British standard (BS) and the Russian standard (GOST) on the rolling die are compared from such a point of view. The method for calculating the tolerance for the blank diameter from the tolerance for rolling die is established under some assumptions. The results of calculations on the above three standards show that the draft of JIS is the most suitable for the present state in Japan.

The Effect of the Thread Rolling Conditions on the Fatigue Strength of the Rolled Screw Threads : 3rd Report, Rotating Bending Fatigue Strength of the Specimens with a Rolled V Groove, Part 2

The Effect of the Thread Rolling Conditions on the Fatigue Strength of the Rolled Screw Threads : 3rd Report, Rotating Bending Fatigue Strength of the Specimens with a Rolled V Groove, Part 2

The Effect of the Thread Rolling Conditions on the Fatigue Strength of the Rolled Screw Threads : 3rd Report, Rotating Bending Fatigue Strength of the Specimens with Rolled V Groove, Part 2

In the first report the published papers on the fatigue strength of rolled screw threads were reviewed, and it was reported that the fatigue strength of rolled screw threads might be affected by the rolling condition. Then the process of thread rolling was analysed theoretically. In the second report the results of the rotating bending fatigue tests on the specimens with rolled V groove were presented. In this experiment the rolling conditions of V groove were changed by varying the number of revolutions of specimen during rolling process. The type of rolling pressure curve was held constant. In this third report the results of the fatigue tests similar to those in the second report are presented. In this experiment the type of rolling pressure curve as well as the number of revolutions of specimen is varied. When the rolling is performed by the usual method using the rolling attachment reported in the second report, the rolling pressure curve becomes an increasing pressure type. Using the same attachment the constant pressure type can be obtained by a simple additional operation. In these two types of rolling pressure curves the V groove is rolled at the three levels of the number of revolutions of specimen. The fatigue tests are carried out on these specimens. The fatigue strength of the specimen with rolled V groove increases with the decrease of the number of revolutions of specimen, and is higher in the constant pressure type than in the increasing pressure type.

The Effect of the Thread Rolling Conditions on the Fatigue Strength of the Rolled Screw Threads : 2nd Report, Rotating Bending Fatigue Strength of the Specimens with a Rolled V Groove

In the first report the published papers on the fatigue strength of rolled screw threads were reviewed, and it was reported that the fatigue strength of rolled screw threads might be affected by the rolling condition. Then the process of thread rolling was analysed theoretically. In the second report the results of the rotating bending fatigue tests on the specimens with a rolled V groove were presented. In this experiment the rolling conditions of V groove were changed by varying the number of revolutions of a specimen during the rolling process. The type of rolling pressure curve was held constant. In this third report the results of the fatigue tests similar to those in the second report are presented. In this experiment the type of rolling pressure curve as well as the number of revolutions of a specimen is varied. When the rolling is performed by the usual method using the rolling attachment reported in the second report, the rolling pressure curve becomes an increasing pressure type. Using the same attachment the constant pressure type can be obtained by a simple additional operation. In these two types of rolling pressure curves the V groove is rolled at the three levels of the number of revolutions of a specimen. The fatigue tests are carried out on these specimens. The fatigue strength of the specimen with a rolled V groove increases with the decrease of the number of revolutions of a specimen, and is higher in the constant pressure type than in the increasing pressure type.

Investigations on the Differential Speed Type Thread Rolling Machine : 2 nd Report, Rolling Power and the Calculation of the Outside Diameter of Rolling Die

In the second report the following problems of the differential speed type thread rolling machine are discussed : (1) the power required for thread rolling, (2) the axial movement of the blank during thread rolling, (3) the calculation of the outside diameter of the die. The tangential force acting on the die is the most important factor of the power required for thread rolling. Also the power consumed at the parts of the power transmission mechanism must be considered. The output of the main motor in the case where the screw thread is rolled by the differential speed type thread rolling machine was measured. The experimental values were compared with the values estimated on the basis of the rolling pressure and the tangential force. Both values show good agreement. It is desirable to make the axial movement of the blank during the thread rolling as small as possible. The amount of the axial movement of the blank on the industrialized machine was measured. The experimental values agree with the values calculated according to Yamamoto's theory. The method of calculating the outside diameter of the die, in which the amount of the axial movement of the blank is minimized and the effective working zones are uniformly distributed over the die surface, was established.

The Effect of the Thread Rolling Conditions on the Fatigue Strength of the Rolled Screw Threads : 1st Report, Investigations on the Thread Rolling Conditions

The published literatures on the fatigue strength of the rolled threads have been surveyed by the author. One of the causes of the difference among the results of these investigations seems to be the thread rolling conditions. If the effect of the thread rolling conditions on the fatigue strength of the rolled threads is clarified, the rolling condition for the rolled threads of fatigue strength extremely higher than that of the cut threads may be obtained. The rolling conditions were analysed for the thread rolling processes used today. From this analysis it has been found that the rolling condition is expressed by the number of revolutions of the blank from the start to the end of rolling and the type of the rolling pressure curve. The rolling pressure curves are classified into 3 types ; namely the decreasing pressure type, the constant pressure type and the increasing pressure type. This analysis was confirmed by the experiments on the oil pressure type thread rolling machine with a special attachment.