RU2199035C1 - Spring nut and method of manufacture of spring nuts - Google Patents

Abstract

FIELD: mechanical engineering; spring nuts for detachable joints of parts working under heavy-duty conditions at continuous vibration. SUBSTANCE: proposed spring nut has body with internal thread and spots for wrench. Body is made in form of cylindrical spring made from wire. Wire has rectangular or another section; direction of winding is opposite relative to direction of thread; ends of turns are bent at angle of 30-60 deg. Each butt of nut has toothed rim. Spots for wrench are made in form of guide projections at ends of nut. Proposed nut may work under heavy-duty conditions without unscrewing. Method of manufacture of spring nuts includes preparation of blanks, heating these blanks, winding them on threaded mandrels, forming thread and heat treatment; simultaneously with forming the thread, members for wrench or other tools are made; hardening of spring nuts is performed when they are placed on threaded mandrels, after which spring nuts are removed from mandrels and are subjected to tempering, blanks are wound on threaded mandrels and are hardened in molding mechanisms either autonomous or located symmetrically on rotor. Prior to hardening, spring nut may be subjected to cubic strain. EFFECT: reduced labor consumption; automation of separate procedures or process as a whole. 5 cl, 7 dwg

Description

 The invention relates to the field of mechanical engineering, and more particularly to spring nuts for detachable connections of parts operating under severe conditions, for example, under constant vibration, as well as to methods for manufacturing such nuts.

 A single-thread nut made of sheet material is known, which is highly resistant to unscrewing by vibration (see SU 50740 of 03/31/1937). This nut is provided with side walls, in which the free edge is bent inward, forming a spring support when tightening the nut. These nuts are single-turn and not designed for heavy loads.

 Known self-locking nut of improved design (see FR 2186077 A), consisting of a single steel part, equipped with cutouts and curved so that it contains several plates interconnected and superimposed to form an S-shaped longitudinal section.

The disadvantages of this design include the following:
- the lack of self-tightening effect, since the end face of the nut is smooth and does not contribute to the transmission of torque that occurs during the vibration of the connected elements,
- incomplete contact of the working (threaded) part of the nut with the working part of the bolt, since the locking of this connection occurs due to the axial shift of the nut plates, while only one side surface of the thread profile is in contact.

 A split nut is also known (see Japanese Patent 47-43099, 1972).

 This design may have a self-tightening effect, but since this effect is uncontrolled, there may come a moment when the front end of the nut can not withstand heavy loads and opens so that it breaks or disengages from the bolt, since the size of the variable section within one turn varies .

 The spring nut SU 1691591 A1, 11/15/1991, F 16 B 37/12 was selected for the prototype. It contains a body with internal thread, a turnkey place. The case of the spring nut is made in the form of a cylindrical spring. The use of this nut for a bolted connection increases its load capacity, however, such a design will not be able to work in conditions of large vibrations without loosening.

 One of the analogues for the method is a well-known method of manufacturing a nut, which provides for the manufacture of a housing with the subsequent formation of an internal thread in it (GOST 5927-70. Hex nuts with accuracy class A. Designs and sizes). The main disadvantage of a threaded connection with such a nut is the unscrewing of the latter with large vibrations.

 The task of improving the quality of products is solved by the method of manufacturing springs, in particular spring nuts, which includes the preparation of blanks, their heating, winding onto a threaded mandrel, thread formation and heat treatment, while each obtained nut is quenched at the moment it is located on a threaded mandrel - SU 816634 A, B 21 F 35/00, 03/30/1981. In this technical solution, a combination of the operations of forming the body of the nut and the internal thread in it is achieved. This allows you to reduce the energy consumption of the process and simplify the possibility of its automation.

 This technical solution is taken as a prototype for the method.

 The challenge facing the authors is to develop such a design of the nut that can work in difficult conditions, in conditions of large vibrations without loosening, i.e. improving the reliability of a threaded connection operating in conditions of large vibrations with a self-tightening effect, including due to a uniform cross section along the entire length of each turn.

 This goal is achieved due to the fact that the body of the spring nut is made in the form of a coil spring of wire. The wire has a rectangular or square section, the direction of winding is opposite to the direction of the thread, the ends of the turns are bent at an angle equal to 30-60 degrees. The number of turns is selected depending on the required strength characteristics of the steel used and operating conditions. The end face of the nut is made with a toothed rim located at the maximum distance from the axis of the nut.

 For the minimum guaranteed interference fit, the average diameter of the thread of the nut is made smaller than the average diameter of the thread of the bolt by the value of the guaranteed interference within the Hooke law, which ensures self-tightening of the nut.

 The nut on a turn-key basis is made in the form of driving ledges - front for tightening, rear for loosening the nut.

 Another objective of the invention is the further improvement of the method of manufacturing spring nuts in order to ensure the small complexity of their manufacture and the ability to automate individual operations or the whole process.

 The problem is solved in that in the method of manufacturing spring nuts, which includes the preparation of blanks, their heating, winding onto threaded mandrels, thread formation and heat treatment, together with the formation of the thread, the key engagement elements or other mounting tool are performed. In this case, the hardening of the spring nuts is performed at the time they are on the threaded mandrels, after which the spring nuts are screwed up and released. Winding of blanks on threaded mandrels and hardening is carried out in several, for example, four, simultaneously involved and symmetrically located on the rotor or autonomous forming devices.

 All devices that are used for preparing workpieces (unwinding used material from a bay (hereinafter referred to as the material), dressing in horizontal and vertical planes, feeding the workpiece to the heating zone, heating with high-frequency currents and cutting the workpiece of the required length depending on necessary height of the nut) are electrically or mechanically interconnected, and since several (four) forming mechanisms are used, the above operations are electrically or otherwise, n example using photocells associated with the position of the individual molding mechanisms.

 In addition, before hardening the body, it is subjected to volumetric deformation. This additional operation is associated with the need to apply threads in which the profile height is more than 1/10 of the profile height of the nut itself.

 The essence of the first object of the invention is a spring nut is illustrated by drawings, where figure 1 shows a General view of a spring nut; figure 2 shows a view of figure 1; figure 3 is a section aa in figure 2; figure 4 - section bb in figure 2.

 Figure 5-7 shows a device for implementing the method of manufacturing spring nuts. A device for forming a housing of a spring nut and thread in it (forming mechanism) contains deformation rolls, a gear drive, a threaded mandrel and a so-called leash connected to it.

 5 is a side view of a device for implementing the method.

 6 is a view a in figure 5.

 7 is a device for additional deformation of the housing.

 The spring nut consists of a housing 1, an internal (with a standard profile) thread 2, and the thread is made with an average diameter smaller than the average diameter of the bolt bolt for which the spring nut is used, by an amount that ensures the minimum guaranteed tightness within the framework of Hooke’s Law, protrusions 3, gear rim 4.

This design was obtained by cylindrical winding of a rectangular cross-section wire from spring steel, heated to a temperature that provides plastic deformation (for example, for steel 65G it is 1200 ^o C), on a threaded mandrel made of heat-resistant steel, with compression in the radial direction for obtaining a complete thread profile with the simultaneous deformation of the lug protrusions and gear rims with the subsequent hardening of the obtained spring nut on a threaded mandrel in order to maintain medium th diameter of thread.

 The spring nut works as follows.

 To maintain the conditions of self-tightening, the winding is performed left-handed with a right-hand thread and vice versa, and for the convenience of twisting and unscrewing, the ends of the first and last turns are made with pull tabs 3. For transmitting maximum torque to the spring nut under vibration conditions, which provides a self-tightening effect, at each end of the spring the nut is made of a toothed rim 4, the most remote from the axis of the spring nut.

 The proposed design of the spring nut allows for reliable connection of machine parts operating under vibration conditions, as well as in the case of wear of the connected elements during temperature fluctuations, as a result of which a gap appears between them and the spring nut begins to automatically tighten under vibration until the resulting gap disappears and the relative vibrations of the connected elements.

 A method of manufacturing a spring nut is as follows.

 The workpiece 5 with a rectangular cross-section, when heated to a temperature of plasticity, passes through a correct feeding device 6, which, in addition to editing, provides the workpiece to the guiding mechanism 7. In addition to the exact direction of the workpiece into the machining zone, the rolls also ensure its displacement during winding onto the threaded mandrel in the forming mechanism during the transition to the next round. The workpiece 5 after entering the deformation rolls falls under the leash 8, which is wrapped together with the threaded mandrel 9. In this case, the deformation roller 10 presses the workpiece into the threaded mandrel 9, and the deformation of the workpiece on the sides is limited to rotating synchronously with the threaded mandrel 9 and the deformation rolls 10, 11 , 12 focus 13.

 The emphasis 13 has the possibility of axial movement for winding the next turn. The deformation of the workpiece is also limited by the housing of the leash 8. The deforming rolls 11 and 12 alternately provide the compression of the workpiece to the complete formation of the threaded profile. After winding the first turn of the spring nut, the guiding device 7 moves the workpiece to a distance that corresponds to the height of the turn.

 The synchronization of the rotation of the threaded mandrel 9 and the deforming rolls 11, 12, 13 is provided by a gear transmission 14, 15.

 The part of the workpiece, which is located under the leash, has no thread and protrudes beyond the boundaries of the main part of the nut body, is used as an engagement element for the mounting tool.

 The described method of manufacturing spring nuts extends to nuts with a small type of thread, that is, to threads that have a profile height of not more than 1/10 of the height of the spring nut.

 If it is necessary to manufacture threads with a profile height of more than 1/10 of the height of the spring nut, the latter is subjected to additional volumetric deformation before quenching using the device shown in Fig. 7 and which consists of a housing 16 with cylindrical holes for pistons 17 on which punches are fixed 18, which compress the nut 1, which tightly fits the threaded mandrel 9. The movement of the pistons 17 is carried out by supplying hydraulic fluid through the pipes 19 and 20.

 The method allows you to form a thread profile with the simultaneous formation of the body of the spring nut, which is self-tightening.

 Hardening of the spring nut is carried out by supplying coolant to its body, which is located in the forming device on the threaded mandrel, after which a special device is used to make the obtained spring nut and release it.

 If the material is used in the bay, its end is fed into the correct feeding mechanism, which ensures its straightening in two mutually perpendicular planes and its feeding into the high-frequency heating zone. After capture by rolls, the material is cut with scissors and the formation of the spring nut body begins.

 Several forming mechanisms are used simultaneously, located, for example, symmetrically on the rotor, the rotation of which is associated with the preparation of workpieces and the basic operations that are performed in the forming mechanisms. When the rotor rotates 90 degrees, the forming mechanism goes into the position of the hardening device. During this time, the spring nut is completely formed and its temperature is reduced to the temperature necessary to begin quenching.

 At the next rotation of the rotor by 90 degrees, the spring nut is screwed from the threaded mandrel and enters the drive. After accumulating the required number of spring nuts, they are transferred to the furnace for tempering.

Claims (5)

1. A spring nut containing a housing with a female thread, a turn-key location, wherein the housing is made in the form of a cylindrical spring of wire, characterized in that the wire has a rectangular or square cross section, the direction of winding is opposite to the direction of the thread, the ends of the turns are bent at an angle equal to 30-60 ^o .  2. A nut according to claim 1, characterized in that a gear rim is made on each of its ends.  3. The nut according to claim 1 or 2, characterized in that the turnkey seats are made at the ends of the nut in the form of pulling protrusions.  4. A method of manufacturing spring nuts, which includes the preparation of blanks, their heating, winding onto threaded mandrels, thread formation and heat treatment, together with the formation of the thread, turn-key engagement elements or other mounting tools are performed, while the spring nuts are quenched when they are threaded mandrels, after which spring nuts are screwed and loosened, billets are wound on threaded mandrels and hardened in several simultaneously and symmetrically operated located on the rotor or autonomous forming mechanisms.  5. The method according to claim 4, characterized in that before hardening the spring nut it is subjected to volumetric deformation.

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