RU2346778C1 - Method for manufacture of compression springs - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: method includes coiling of spring from polished or patented wire with pitch that exceeds pitch of finished spring, thermal treatment, shotcasting riveting and spring pressing by means of its yield by axial load of (10÷300) F₃ value, where F₃ is spring force at maximum deformation. At that high-temperature thermomechanical treatment of wire is carried out prior to spring coiling.

EFFECT: spring operational properties are improved.

5 cl

Description

The invention relates to technologies for manufacturing helical compression springs operating in the normal mode or with the collision of coils, from a patented or polished wire before winding. It can be used in the manufacture of springs operating both at ordinary and at high temperatures.

A known method of manufacturing compression springs according to US Pat. RU No. 2275270 C1, including winding the spring in increments greater than the finished spring pitch, heat treatment, shot blasting, after shot blasting, the spring is pressed by an axial load (10 ÷ 300) F ₃ , where F ₃ is the spring force at maximum deformation, and repeatedly pressing by a load increased in proportion to the ratio of the required draft to draft from the application of the first load [5]. In this case, the loads can be vibrational [6]. Upon reaching a predetermined spring height, re-pressing is not necessary. With increased requirements for the power parameters of the spring after winding, dressing and grinding of the ends with removal of bevels on them.

But during the operation of springs at elevated temperatures, their settlement and loss of operational properties occur. Therefore, before the operation of winding the springs, the wire should be subjected to high-temperature (HTMT) thermomechanical processing [1], which is based on combining the operations of hot metal forming (rolling, drawing, bending or winding at small radii) with subsequent immediate hardening at regulated temperature and time parameters. After HTMO, an increase in strength is ensured, fatigue strength (including low cycle strength) is increased, as well as fracture resistance, ductility and toughness, the cold temperature is lowered, reversible temper brittleness is practically eliminated and hydrogen embrittlement is reduced. In this case, the material of the wire can be subjected to single or double electroslag remelting, which reduces the size of non-metallic inclusions and increases the endurance of the springs. In the manufacture of wire to remove defects on the outer surface, turning with a cutter head, grinding, polishing can be used.

The proposed manufacturing process for the manufacture of compression springs from a conventional, polished or patented wire, including winding the spring in increments, exceeding the finished spring pitch, heat treatment and shot blasting, pressing the spring with an axial load of (10 ÷ 30) F ₃ , where F ₃ is the spring force at maximum deformation, it differs in that before winding the springs, they perform the process of high-temperature thermomechanical processing of the wire and, if necessary, tempering. When covering the spring, at first, a load is applied that provides its minimum permissible draft when working in the product, and then a repeated load is applied, increased in proportion to the ratio of the required draft to draft from the initial load [5]. In this case, the load can be applied vibrationally [6]. With increased requirements for the power parameters of the spring after winding, dressing and grinding of the ends with removal of bevels on them.

The determination of both the initial load during plastic hardening of the spring coils and the step size during winding under hardening are known and sufficiently illuminated [3, 4] in the literature and do not cause difficulties.

The method is as follows. The brushed or patented wire is subjected to HTMO and, if necessary, tempering, then the wire is fed to a spring-coiling machine or automatic machine and the spring is wound in increments exceeding the pitch of the finished spring. Produce heat treatment of the spring. After 100% luminocontrol and washing, a shot blasting is carried out. Then press the spring until the desired height of the spring is achieved by compressing it with a load (10 ÷ 300) F ₃ . Then measure the parameters of the spring. Recent operations - protective coating, preservation and packaging. In the manufacture of springs that are accurate in terms of power parameters, after winding, they are straightened and the ends are ground with chamfering.

Note. Methods of high temperature thermomechanical hardening are diverse and are presented in the following patents.

1. A.S. 528989 USSR, IPC B21F 3/04. A method of manufacturing springs. / Shavrin O.I., Redkin L.M., Kreknin L.T. - No. 2100900/02; declared 01/31/75; publ. 09/25/76. Bull. No. 35. - 2 p.

2. A.S. 882687 USSR, IPC B21F 3/04, B21F 35/00, C21D 9/02. A method of manufacturing springs. / Shavrin O.I., Redkin L.M., Konyshev V.N., Kotelnikov A.V., Yakovlev Yu.T., Grigoriev V.K. - No. 2782490 / 25-12; claimed 06/19/79; publ. 11/23/81. Bull. No. 43. - 2 p.

3. A.S. 1234018 SU, IPC B21F 35/00. A method of manufacturing large springs. / Shavrin O.I., Redkin L.M., Scherbakov V.I., Maslov L.N., Konyshev V.N. - No. 3781269 / 25-12; claimed 08.13.84; publ. 05/30/86. Bull. No. 20. - 2 p.

4. A.S. 1509161 SU, IPC B21F 3/04. A method of manufacturing springs. / Redkin L.M., Konyshev V.N., Malkov A.A., Kotelnikov A.V. - No. 4341421 / 31-12; Declared 10.12.87; publ. 09/23/89. Bull. Number 35. - 2 p.

As a result of developing a comprehensive technology for the manufacture of springs, industry specifications have been developed for the supply of thermomechanically hardened wire from steel 65S2VA - TU AEZH 347-82 (INIMT); from steel 51KhFA and 60S2A - TU AEZh V3-350-88 (INIMT) and TU VZ-350-88 (IZHSTAL) [4].

Consider in detail the method for A.S. 1509161 SU. Alloy steel wire is subjected to high-temperature thermomechanical drawing by drawing on a special installation, and after HTMO they are given average tempering. Next, cold plastic deformation is carried out by drawing with a degree of deformation of 15 ... 50% (for a section of about 2 mm - 50%, over 5 mm - 15%). By cold winding on automatic machines or bending, springs are made with subsequent tempering at a temperature not exceeding the tempering temperature of the hardened wire.

The use of cold plastic deformation with a degree of less than 15% leads to an uneven hardened state over the cross section of the wire, leading mainly to hardening of the surface layers of the metal. Subsequent cold deformation during winding operations, skewing neutralizes the effect of preliminary hardening. Deformation with a degree of more than 50% begins to create foci of local overstrain in the thermomechanically hardened material of the wire, which lead to the appearance of fatigue cracks and, thus, to premature failure of the springs.

The method was tested in the manufacture of diesel nozzle springs from 51XFA - VTMO wire ⌀ 2.6 mm, the number of working turns is 6.5, the total number of turns is 8.5, the height is 26 mm, and the outer diameter is 11.8 mm. As a material for the study, we used a wire made of 51KhFA steel with a diameter of 3.5 mm after HTMT drawing by a special installation, electrical tempering hardness HRC42-48 at a temperature of 350-400 ° C on the same installation and cold plastic deformation by drawing on a 1/550 mill up to a diameter of 2.6 mm. After winding, the springs were released at 320 ± 10 ° C for 1 h.

Experienced springs are tested on a fatigue bench. Comparison is made with the endurance of serial springs and springs from 51XFA-VTMO wire (without additional hardening). Studies have shown that the endurance of experimental springs made of 51KhFA-VTMO steel with additional cold plastic deformation of the wire is higher than the endurance of control springs by 1.8-2.5 times. Thus, the proposed method provides increased performance of the springs.

But not in the conditions of operation of the spring with a power contact or a collision of coils.

Information sources

1. Rakhstadt A.G. Spring steel and alloys. / M .: Metallurgy, 1982.

2. Patent RU No. 2275270 C1, IPC B21F 35/04, C21D 9/02, 2006.

3. Tebenko Yu.M. Problems of production of high-speed springs and ways to solve them. Monograph. - Stavropol: LLC “Data World”, 2007, 152 p.

4. Zemlyanushnova N.Yu. Calculation of helical cylindrical compression springs in contact overburdening. Monograph. - Stavropol: “Agrus”, 2008, 136 pp.

5. USSR copyright certificate 554915, M.cl. B21F 35/00, 1975.

6. Copyright certificate of the USSR 580474, M.cl. G01M 13/00, B21F 35/00, 1976.

Claims (5)

1. A method of manufacturing compression springs from polished or patented wire, including winding the spring with a step exceeding the step of the finished spring, heat treatment, shot blasting and pressing of the spring by its precipitation with an axial load of (10 ÷ 300) F ₃ , where F ₃ is the spring force at maximum deformation, characterized in that before winding the springs produce high-temperature thermomechanical processing of the wire. 2. The method according to claim 1, characterized in that when pressing is applied a repeated load increased in proportion to the ratio of the required draft to draft from the application of the initial load. 3. The method according to claim 1 or 2, characterized in that the load is applied by vibration. 4. The method according to claim 1 or 2, characterized in that after winding, the spring is straightened and its ends are polished with chamfers removed. 5. The method according to claim 1, characterized in that the tempering wire, which has passed high-temperature thermomechanical processing.