CN100386157C - A closed three-bar bearing frame - Google Patents

Abstract

A closed three-bar load-bearing frame is composed of a lower beam and two columns with non-parallel axes, and the connections between the three bars are connected by prestressed and non-prestressed bars. There are many derivative types of the three-bar bearing frame: such as the partially parallel axis type, the arc column type, the arc beam type and their composite types. The upper space of the three-bar load-bearing frame is small and the lower space is large. For the situation that the space required by the pressure generating parts is much smaller than the material forming space, the space utilization rate of the three-bar frame is high, so it is small in size, light in weight and low in cost. It is especially suitable It is used in a wide range of fields such as free forging press frames, expansion press frames, and sheet drawing forming press frames.

Description

A closed three-bar bearing frame

technical field

The invention belongs to bearing equipment used in industrial fields such as heavy equipment and heavy machinery, and in particular relates to a closed bearing frame.

Background technique

The closed frame structure referred to in the present invention is a closed load-bearing frame, which is used for rolling mill load-bearing frames, mechanical press frames, friction press frames, hydraulic press frames, counter-hammer frames and electric screw hammer machines. racks and so on. Since the Industrial Revolution in the 19th century, all closed bearing frames can be simplified to a structure consisting of four rods, as shown in Figure 1. The vertical members are called columns, and the horizontal members are called beams. There are two beams and two columns. The load on the beam and column can be approximately simplified as the load P and moment M perpendicular to the axis of the member, and some of P and M on the four members can be zero. This kind of closed load-bearing frame is characterized in that the axes of the two columns (centroid connection) are straight and parallel, and the spans of the two beams (upper and lower beams) are equal and parallel to each other. In addition, the load-bearing frame All have a vertical axis of symmetry V-V', and sometimes a horizontal axis of symmetry H-H' (as shown in Figure 2).

This kind of frame composed of four rods can be called a four-bar system closed frame (abbreviated as a four-bar frame). In engineering, several four-bar racks can also be superimposed to form a rack with a wide table, as shown in Figure 3. After the superposition, the upper and lower beams are combined to form the upper and lower beams of the wide table. For example, two four-bar racks are superimposed to form the most typical four-column closed rack, as shown in Figure 4. For more than 200 years, all kinds of load-bearing closed frames used in various industries are four-bar frames and their combined superposition structures.

The biggest disadvantage of the four-bar rack is that it cannot effectively use the space and the material utilization rate is low. The expansion tube press shown in Figure 5, because the required pressure is not large, this type of press has only one working cylinder supported on the upper beam; the space above the lower beam is the mold installation space, because the expansion mold is large in size, Therefore, the size of the lower beam is relatively large. Since the axes of the four columns are parallel and the spans of the upper and lower beams are equal, the upper beam is also forced to be designed to be very large, as shown in Figure 5. The function of the upper beam is to take the loads from the hydraulic cylinders and transfer them (force and moment) to the column. The upper beam should be designed as a beam with a small span (as shown by the dotted line in Figure 5), but due to the constraints of the four-column closed frame structure, its span has to be stretched to be as large as the lower beam, resulting in a lot of waste ( A and B are idle spaces). Another example is the free forging hydraulic press, the forging part requires a huge space, and when using a higher medium (oil, water, etc.) working pressure, it can be designed as a cylinder without requiring a lot of space. For example, for a single-cylinder 6,000-ton free forging hydraulic press, when the working pressure of the medium is 390kgf/cm ² , the outer diameter of the main cylinder can be designed to be Φ1.7m, and the forging space needs to be 4.6m, which is three times the former, as shown in Figure 6 shown. The upper beam is designed according to the main cylinder, and its span is 1.75m, but if the upper beam is designed according to the requirements of the forging space, its span should be at least 4.6m. The span value determines the height, weight and processing, transportation and installation costs of the beam, which is very unreasonable and causes huge waste.

The space required for the pressure-generating parts of various bearing frames is less than the space required for installing molds and material forming, which makes the four-bar system frame unsuitable for many working conditions, especially the bearing frame of a wide table and small tonnage press. The four-column racks have parallel column axes and equal spans of the upper and lower beams, which are unreasonable in many wide-table racks. more and more obvious.

Contents of the invention

The purpose of the present invention is to provide a closed three-bar closed frame that can improve the space utilization rate of the load-bearing frame, reduce the volume of the machine, reduce the weight of the machine, and reduce the processing cost in view of the shortcomings and defects of the existing four-bar closed frame. The pole carries the rack.

Above-mentioned purpose of the present invention is achieved through the following technical solutions:

A closed three-bar load-bearing frame, characterized in that: the load-bearing frame adopts a three-bar closed structure, and the three-bar closed structure is composed of a lower beam and two columns whose axes are not parallel. The connection adopts prestressed rod system connection and non-prestressed rod system connection.

The prestressed rod system connections in the present invention include hinged joints, rigid connections and buckle connections; non-prestressed rod system connections include hinges and rigid connections.

In the present invention, the lower beam of the closed three-bar load-carrying frame can adopt a horizontal beam or an arc beam, and the two columns with non-parallel axes can adopt two straight columns, two partial axis-parallel columns or two arc columns.

The prestressed connection described in the present invention is to add a transition piece between the rods, and preload it with a pretensioning piece. The said pretensioning piece adopts a steel wire winding or a mechanical device that can generate a pretensioning load; the steel wire winding On the outer contour of the frame of the three-bar closed structure, the steel wire with tension is wound to form a steel wire layer.

Compared with the four-rod closed frame, the present invention has the following advantages and prominent effects: ① The present invention breaks the structural pattern of the traditional four-bar closed frame, not only has a simple structure, but also has structural stability and uniqueness. ②The narrow upper space of the frame can be used to arrange pressure generating components, such as working cylinders; the wide lower part is suitable for arranging material processing components, such as molds, etc., thus effectively improving the utilization rate of the rack space, reducing the volume of the machine, and reducing the weight of the machine. weight, reducing processing costs.

Description of drawings

Figure 1 is a schematic diagram of a closed bearing frame composed of four rods.

Fig. 2 is a schematic diagram of a two-beam and two-column closed bearing frame.

Fig. 3 is a superimposed schematic diagram of multiple four-bar racks.

Figure 4 is a schematic diagram of a typical four-column closed rack.

Fig. 5 is a schematic diagram of a tube expansion press in the prior art.

Fig. 6 is a schematic diagram of a single-cylinder 6,000-ton free forging hydraulic press in the prior art.

Fig. 7 is a schematic diagram of the transition from a four-bar closed frame to a three-bar closed frame.

Fig. 8 is a schematic diagram of the three-bar closed load-carrying frame provided by the present invention with the addition of transitional rims.

Fig. 9 is a schematic diagram of a steel wire wound three-bar load-carrying frame.

Fig. 10 is a schematic diagram of a three-bar load-carrying frame with a partial axis parallel structure.

Fig. 11 is a schematic diagram of a three-bar bearing frame with an arc column structure.

Fig. 12 is a schematic diagram of a three-bar bearing frame with a curved beam structure.

Fig. 13 is a schematic diagram of a three-bar bearing frame connected by hinges.

Fig. 14 is a schematic structural view of the three-bar bearing frame of the 6,000-ton free forging hydraulic press provided by the present invention.

Figure 15a is a traditional four-column frame of a 1250-ton free forging hydraulic press.

Fig. 15b is a schematic structural diagram of a three-bar bearing frame of a 1250-ton free forging hydraulic press provided by the present invention.

Detailed ways

The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

The bearing frame adopts a three-bar closed structure. The three-bar closed structure is composed of a lower beam and two columns with non-parallel axes. connect. As shown in Figure 7, a horizontal bar (upper beam) is reduced to form a three-bar system; two vertical bars evolve into two oblique bars, their axes are not parallel, and the intersection point is the highest point of the rack; the only horizontal bar is the lower bar Beam, which intersects two oblique bars; compared with the four-bar system, when the length of the bar is determined, the three-bar system can only form a unique structure, while the four-bar system forms an uncertain structure, so the former has better rigidity than the latter. The closed three-bar bearing frame is referred to as the three-bar frame for short. Its upper space is small, which is suitable for the placement of pressure generating components; while the lower space is large, which is suitable for the setting of material forming components. It fundamentally solves the huge contradiction caused by the space difference between the pressure generating part and the material forming part.

In order to ensure the reliable connection between the three bars, the connection between the bars in the present invention adopts two types of connections: prestressed bar system connection and non-prestressed bar system connection. Non-prestressed connections can be further divided into hinges (as shown in Figure 13, the four-bar rack does not allow hinged connections between bars, because at this time the four-bar rack will change shape arbitrarily, and there is no rigidity to speak of) and rigid connections (welding, pin key, bolt mechanical connection), and prestressed connection can also be divided into hinged joint, rigid connection (welding, pin key, bolt, etc.) Hedge connection is a kind of prestressed connection, that is, by applying prestress and special treatment to improve the coefficient of friction on the surface of the hinge, so that the connection surface has sufficient normal pressure and friction to achieve a reliable connection. In order to improve the manufacturability, a transition piece 1 is added at the connection of the three rods, as shown in Fig. 8 . In order to provide sufficient pre-tightening force for the joint interface, it is necessary to pre-tighten the three-bar system structure with pre-tightening parts. , Bolt pre-tightening and wire winding process, etc. The steel wire winding method is simple and feasible: use a steel wire with a certain tension to wrap the outer contour of the three-bar load-carrying frame to form the winding layer 2—the pre-tightening layer to generate pre-tightening force, as shown in Figure 9. There are many variants of the three-bar loading frame to suit different working conditions. Figure 10 is a schematic diagram of a closed three-bar load-bearing frame with a local axis parallel structure, Figure 11 is a schematic diagram of a closed three-bar load-bearing frame with an arc column structure, and Figure 12 is a schematic diagram of a closed three-bar load-bearing frame with an arc beam structure. The three-bar system structure can also adopt the composite structure of the above structures.

The spatial scale ratio λ of the supporting frame can be used as the discriminant value for using a four-bar frame or a three-bar frame. λ is calculated with the following formula:

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}$

_Lc is the spatial dimension of the pressure generating components, such as the outer diameter of the working cylinder;

L _M is the spatial dimension of the material forming part, such as the maximum size required by the mold;

when:

λ≤2→A four-bar system frame is adopted;

λ>2→A three-rod frame is used.

List several embodiments below to further understand the present invention:

Example 1: Frame design of 6000 ton open die forging press

For example, the single-cylinder 6,000-ton free forging hydraulic press frame L _M = 4.6m, L _C = 1.7m, $\mathrm{\&lambda;}=\frac{4.6}{1.7}=2.7$ , so it is more appropriate to design a three-bar rack.

In Fig. 14, a, c and e form a three-bar rack with parallel local axes. b, d and f are the buckle transition blocks added for connecting the bar system, K ₁ , K ₂ , K ₃ , K ₄ , K ₅ and K ₆ are the buckle joint surfaces, and 2 is the pre-tightened steel wire layer. The frame can withstand a working load of 6,000 tons and weighs only 400 tons, while the frame of a traditional 6,000-ton free forging press weighs at least 800 tons.

Example 2: 1250-ton press frame design

The design of the four-column frame of the 1250-ton free forging press adopts 330kg/cm ² working oil pressure, and the working outer diameter of a single master cylinder is Φ820mm, that is, L _c = 820mm, while the forging space scale is 1940mm, L _M = 1940mm

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1940</span>}}{\mathrm{<span\; class="notranslate">\; 820</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2.36</span>}$

Therefore, it is more reasonable to design the frame of the 1250-ton free forging hydraulic press as a three-bar frame, which is 40 tons lighter than the four-bar frame. Figure 15a is a traditional four-column rack, and Figure 15b is a three-bar rack. Their drawing scales are the same. The former has 4 columns of Φ300; the latter only designs two hollow columns, the upper beam is greatly reduced, and the movable beam and lower beam are smaller than the former. It can be seen that the three-bar frame is small in size and light in weight. For a press frame of such a small tonnage as 1250 tons, the weight can be reduced by tens of tons.

Claims (5)

1. closed type three poles framework for support, it is characterized in that: this framework for support adopts three rod member closed type structures, this three rod members closed type structure is made up of a underbeam and two uneven posts of axis, and the connection between three bars adopts the prestressing force leverage to connect or non-prestressed leverage connects.

2. according to the described closed type three poles framework for support of claim 1, it is characterized in that: described prestressing force leverage connect adopt hinged, be rigidly connected or bank closes connection; Described non-prestressed leverage connects the employing hinge or is rigidly connected.

3. according to claim 1 or 2 described closed type three poles framework for support, it is characterized in that: described underbeam is horizontal beam or camber line beam, and described two uneven posts of axis adopt two right cylinders, two local axis parallel columns or two camber line posts.

4. according to the described closed type three poles framework for support of claim 2, it is characterized in that: it is to add transition bank component between rod member that described bank closes connection, and carrying out pretension with preload piece, described preload piece adopts steel wire to twine the mechanical device that maybe can produce prefastening load.

5. according to the described closed type three poles framework for support of claim 4, it is characterized in that: it is on the frame outline of three bar closed type structures that described steel wire twines, with the steel wire winding formation steel wire floor of belt tension.

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