RU2193988C2 - Hitch mechanism - Google Patents

Abstract

FIELD: transport engineering. SUBSTANCE: mechanism has head and tail parts and fastening members. Slots are made on outer surface of tail part its fastening to vehicle. Surfaces of slots and fastening members fitted in slots have several transition radii. EFFECT: increased fatigue strength of structure owing to reduction of concentration of stresses in zone of fastening and prevention of formation of cracks. 2 cl, 6 dwg

Description

 The invention relates to transport, in particular to the coupling devices of vehicles, and may find application in railway and automotive engineering.

 Various coupling devices for securing various parts of a railway vehicle are known, in which a through hole is made in the rear of the coupling for receiving a fastening rod (e.g. GB 1214752, B 61 G 1/28 or US 4081082, B 61 G 1/38).

 Closest to this invention is a known coupling device comprising a head part, a tail part for attaching to vehicle parts and fastening elements (RU 2028958 C1, B 61 G 1/28, 02.20.1995). The head part is used for engagement with a similar head part of the adjacent coupling device, and the tail part is used for fastening to the parts (depending on the version - a collar or absorbing device) transmitting traction or impact force to the vehicle frame (body). In the rear part there is an opening in which a rod is inserted, through which fastening to the parts is carried out.

 A disadvantage of the known structures is the formation of cracks A and B (see Fig. 1), developing from the hole, which is a geometric concentrator.

 The objective of the invention is to increase the fatigue strength of the structure by reducing the stress concentration in the attachment zone and to prevent cracking.

 To solve this problem, it is proposed to change the design of the tail section, replacing an elongated hole with the corresponding grooves. Those. in a coupling device comprising a head part, a tail part for fastening to vehicle parts and fastening elements, elongated grooves opposite each other are made on the outer surface of the tail part, and elements for fastening to vehicle parts are placed therein.

 In addition, the surface of the grooves and the fastening elements housed therein are configured to provide a minimum stress concentration.

 Figure 1 presents a known device; figure 2 - coupling device according to the invention; figure 3 - one of the embodiments of the coupling device.

 The coupling device comprises a head part (not shown) and a tail part 1. On the outer surface of the tail part 1, grooves 2 are made opposite to each other, into which rods 3 are inserted for fastening with the vehicle part 4. In the detail 4 can be made reciprocal grooves under the rod (Fig. 2). In another embodiment, the vehicle part 4 can be made integrally with the fastening elements (Fig. 3).

 The surface of the grooves of the rear part and the surface of the fastening elements are designed to reduce the stress concentration in the zones of cracking, for example, has several transition radii or a set and combination of other curves and lines.

 In the known coupling device (see figure 1), the loads are transmitted as follows. The tensile force is transmitted through the rod to the jumper of the tail end hole, and the compressive force is perceived by the end face of the shank interacting with the thrust plate. As the calculations of the stress state show, under the action of a tensile force in the zone of formation of crack A, high compressive stresses arise, and the magnitude of the stress component in the direction of loading (crack development) is approximately 1.5 ÷ 2 times larger in absolute value than in the perpendicular direction. In the zone of crack B, tensile stresses arise, which are approximately 2–2.5 times smaller in absolute value than compressive stresses in the direction of the load.

Figure 4 presents the isopole of the main stresses σ ₁ and σ ₃ acting in the tail of the basic design of the automatic coupling of the rolling stock CA-3, under tension (figure 4, a, b) and compression (figure 4, c, d) load 100 tf

 From the compressive force in the zone of the crack A, high tensile stresses appear, oriented toward opening the crack, and in the zone of the crack B, high compressive stresses comparable in absolute value arise.

 That is, for one tensile-compression cycle, with equal tensile and compressive loads, an approximately symmetrical loading cycle is formed in the zone of crack B, and more complex loading is formed in the zone of crack A: almost pulsating compression in the direction of crack development, and in the perpendicular direction (crack opening direction A) - loading cycle with a maximum absolute value of compressive stress, approximately 1.5 times greater than tensile stress.

 Such a stress state during operation leads to the formation of corresponding cracks A and B and a further fracture of the design of the coupling device. Moreover, as statistics show, the most common kink is a kink along crack A, which is confirmed by large values of the stress amplitudes acting in this zone.

 In the proposed coupling device according to the invention (see FIG. 2), the tensile force is transmitted through the rod to the rounded part of the groove, and the compressive force, as in the known device, is perceived by the end face of the shank interacting with the thrust plate.

In FIG. 5 and 6 show an isopole of principal stresses σ ₁ and σ ₃ acting in the tail of the variants of the proposed construction of the tail according to the invention under tension (FIG. 5, a, b and FIG. 6, a, b) and compression (FIG. 5 , c, d and Fig.6, c, d) with a load of 100 tf.

For different versions of the grooves from tensile forces in zone B, due to a combination of several rounding radii, etc., the main tensile stresses decrease by 10-12% compared with the same zone of the known device with an elongated hole. Zone A in the proposed device is virtually absent, although compressive stresses σ ₃ arise in the contact zone near the outer part of the groove, 1.4–2 times smaller in absolute value than in the contact zone of the known device.

 From the compressive force in zone B of the proposed coupling device, low compressive stresses arise. Those. for a tensile-compression cycle in this zone, a cycle will be formed with a stress amplitude much less (about 1.7 times) than for a coupling device with an elongated hole. Zone A under compressive loading is also virtually absent.

 Therefore, the implementation of the tail part according to the invention eliminates the main damage to the shank (zone A of figure 1) and provides a reduction in stress concentration in hazardous sections (crack zone B of figure 2), which leads to an increase in the service life of the coupling device and associated elements.

Claims (2)

 1. A coupling device comprising a head part, a tail part for attaching to vehicle parts and fastening elements, characterized in that on the outer surface of the tail part grooves are made opposite to each other, and elements for fastening to the vehicle parts are placed in them, the surfaces of the grooves and the fastening elements placed in them have several transition radii.  2. The device according to claim 1, characterized in that the transition radii are combined with straight lines.

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