EP3971125B1

EP3971125B1 - High strength boom structure

Info

Publication number: EP3971125B1
Application number: EP20208793.8A
Authority: EP
Inventors: Bahtiyar ERKIN
Original assignee: Erkin Ismakinalari Insaat Sanayi Ithalat Ihracat Ticaret Pazarlama Ltd Sirketi
Current assignee: Erkin Ismakinalari Insaat Sanayi Ithalat Ihracat Ticaret Pazarlama Ltd Sirketi
Priority date: 2020-09-21
Filing date: 2020-11-20
Publication date: 2024-04-24
Anticipated expiration: 2040-11-20
Also published as: EP3971125A1; TR202014990A2

Description

Technical Field

The invention relates to booms used in the cranes, enables the crane to reach far distances by telescoping.
The invention is particularly related to booms obtained by forming two different sheet plates to be used as upper and lower parts by bending them many times and thus obtaining booms with high strength.

State of the Art

Today, cranes are used for the operations such as lifting and transferring all kinds of loads, loading and unloading. While the foldable cranes can be used in narrow areas effectively and under the roofs; telescopic crane is generally used in open areas where length in meters is required.
Telescopic and folding boom cranes consist of telescopic booms. Easy access to the loads at a long distance/depth is provided with the extension of these booms sliding over each other and the location of the loads can be changed easily.
The load to be lifted is engaged to the boom as it is known in the boom profile and engaged load forms buckling and bending force on the boom. In detail, the load applied to the end of the boom applies tension force to the upper part of the boom and applies compression force to the lower part of the boom.
Booms that are produced in the prior art are generally formed by bending a single piece of high strength steel sheet several times and subsequently joining the same from the upper or lower part of the boom by means of welding. In general, the upper part is formed by bending from 3 points; the lower part is formed by bending from 3 or 5 points. This cannot fulfill the strength value of the boom structure.
In the state of the art, when insufficient number of bends is made to the upper and lower part constituting the boom, the following problems occur:

It leads not to provide the balance between the specific gravity / lifting capacity of the booms fully.
Since the welding points are located on the lower and upper ends of the boom where the boom is most exposed to stress; too much load is exposed to the welds and it is required to use high strength welding materials. Welding must be done rigorously and carefully. Specific welding methods must be used so as to strengthen the welding. This leads to high labor operations.
Thickness of the lower and upper parts of the boom profile is same since the boom profile is manufactured from a single piece steel plate. When the profile thickness of the boom is more, it leads to increase in weight and decrease in lifting capacity. Excessive reduction in the thickness of the boom profile leads to structural instability and reduces the resistance of the profile against bending and tearing.
It limits the resistance of the booms against normal stress and buckling.

As a result of the researches made in the literature, various structures are encountered regarding said crane booms. One of them is the patent application numbered TR2012/11127 In the abstract of the invention with classification number B66C 23/04, the following statement takes place; " The invention relates to a boom mouth strip structure which is developed to eliminate the deformations on the boom end portions that occur during use of crane in the boom extension systems of the foldable boom cranes. In the configuration of the inventive boom mouth strip, steel plates which are placed mutually and the strength of which are increased by placing reinforcement plates and extension cylinder connection plates between them, are used."
Another example of the abovementioned structure is the patent with the application number TR2012/13054 .
As a result of the research document numbered EP2078693A1 was encountered. This document discloses the preamble of claim 1.
A support plate is added to the mouth portion so as to reinforce the boom structure in the first application mentioned above. An improvement is made in the profile section in the other application. However, the required strength values cannot be obtained since the number of bends in the general structure of the boom is few in these two applications. Therefore, these applications can be referred as examples to the above mentioned disadvantages.
As a result; parallel to the developing technology in crane booms, developments are made, therefore new configurations are required in order to eliminate abovementioned disadvantages and bring solution to current systems.

Purpose of the Invention

The invention is related to crane booms which is different from the structures used in the state of the art, is developed to solve said disadvantages and brings some additional advantages.
The inventive boom structure is formed by joining two separate sheet plates that are different from each other at certain points.
The purpose of the invention is to change the lower and upper thicknesses of the boom by producing the same from two different parts. Moreover, steels with different strength can be used in the upper and lower sections. Thus, the weight of the boom is reduced.
Another purpose of the invention is to eliminate the requirement of specific welding method and labor for the welding process made from this surface since the sections to be affected least from the stresses on the boom are the side surfaces.
Since the highest amount of pressure during lifting affects the lower part of the boom, another aim of the invention is to increase the strength of this part by forming the lower part by bending the same from 9 points. Therefore, it will be resistive against the highest pressure. In general, the buckling resistance of the boom under excessive load is increased.
The upper part is formed by bending the same at 5 points so as to meet the tensile strength affecting the upper surface during lifting load. Therefore, the pressure force affecting the upper section of the boom is distributed to 4 small parts equally. The upper section of the boom can be produced from a thinner sheet metal by means of this method. This helps to decrease the weight of the boom.
The structural and characteristic features of the present invention will be understood clearly by the following drawings and the detailed description made with reference to these drawings. Therefore the evaluation shall be made by taking these figures and the detailed description into consideration.

Brief description of the Figures Clarifying the invention

Figure - 1; shows the perspective view of the crane.
Figure - 2 is a front section view of the inventive boom in a disassembled state.
Figure - 3 is a front section view of the inventive boom in an assembled state.
Figure - 4 is a perspective view of the inventive boom in a ready to use state.
Figure - 5 shows the angles of the bending points of the upper and lower part forming the inventive boom.

Reference Numbers

1. Crane
10. Boom
11. Upper part
12. Lower part
13. Weld groove
14. Bending points
α. Bending angle
β. Bending angle
γ. Bending angle
θ. Bending angle
Ω. Bending angle

Detailed Description of an Embodiment of the Invention

In this detailed description, the preferred embodiments of the inventive boom (10) is described only for clarifying the subject matter in a manner such that no limiting effect is created.
The crane (1) consists of telescoping booms (10) which can be opened and closed. In Figure 1, the general structure of the crane (1) is given. As can be seen in the figure, minimum one and maximum ten booms (10) are inserted within one main boom. These booms (10) provide to extend the length of the crane by coming out from each other longitudinally by being controlled hydraulically and mechanically.
The invention relates to the production phase of the boom (10) which is formed by bending 2 different sheet plates, the upper part (11) and the lower part (12), in the bending machine. The weld grooves (13) found in these two parts is positioned on top of each other and welding is performed from this section. In other words, welding grooves are positioned both sides of the boom. With this method, welding is protected from high tensile forces. Figure 3 shows the sectional view of the upper part (11) and the lower part (12) which are mounted to each other by means of welding.
The upper part (11) and the lower part (12) can be produced with different thicknesses since the boom (10) consists of two separate parts. Therefore, the weight of the boom (10) can be decreased.
High amount of pressure affects the lower part of the boom due to the load applied to the end of the boom (10) during use. The lower part (12) is formed by bending from 9 different bending points (14) so as to decrease the pressure force that comes under the boom and to increase the strength of the lower part. In Figures 2 and 3, 9 different bending points (14) at which the lower part (12) is bent is seen. Therefore, the pressure force affecting the lower part of the boom (10) is distributed to 8 small parts equally. This bending method substantially increases the strength of the lower part (12) of the boom (10). In general, the buckling resistance of the boom (10) under excessive load is increased.
The 2^nd biggest force that affects the boom (10) is the tensile force affecting the upper surface of the boom (10). In the same way, the upper part (11) of the boom (10) is formed by bending from 5 different bending points (14) so as to decrease the tensile force that comes on the boom (10) and to increase the strength of the upper part. Therefore, the pressure force affecting the upper part (11) of the boom (10) is distributed to 4 small parts equally. The upper section (11) of the boom (10) can be produced from a thinner sheet metal by means of this method. This helps to decrease the weight of the boom (10). Figure 4 shows the perspective view of the last assembled boom (10).
The bending angles of the lower part (12) and upper part (11) must be at certain intervals so as to operate the invention in a healthy manner. Figure 5 shows these bending angles in detail.
As can be seen in Figure 5, the bending angles of the upper part (11) which is bent from 5 different bending points (14) are preferred such that they are between 128-158 degrees. The side sections of the upper part (11) are bent with Ω angle and Ω angle is preferably 131 degrees. The middle bending point (14) of the upper part (11) is bent with γ angle and γ angle is preferably 155 degrees. In conclusion, the bending points (14) formed on both sides of the middle bending point (14) of the upper part (11) are bent with θ angle and θ angle is preferred as 151 degrees. Consequently, 5 different bending points (14) at which the upper part (11) is bent were bend at 3 different angles as Ω, θ, γ angles. Among bending angles, there is the relationship such that γ is greater than θ and θ is greater than Ω as it can be understood from the above mentioned numerical values.
The lower part (12) is bent at 9 different bending points (14). These bending points (14) must be preferred between 156 and 165 degrees. The bending points (14) in the head sections are bent with α angle. α angle is preferred as 159 degrees. The other 7 bending points (14) formed in the middle part is bent with β angle and β is preferred as 160 degrees. As a result, two of 9 bending points (14) where the lower part (12) is bent are bent with α angle; the remaining seven are bent with β angle. There is a relation such that β is greater than α as it can be understood from the given numerical values.
The forces applied to the lower and upper parts of the boom (10) are provided to be distributed over the boom (10) surfaces equally by means of bending the upper part (11) and lower part (12) with the above mentioned angles.

Claims

A boom (10) used with a telescopic structure in the telescopic crane (1) so as to lift the loads that are at a far distance/depth, characterized by comprising;
• an upper part (11) which forms the upper section of said boom (10), is formed by bending from bending points (14) determined at equal intervals and the strength of which is increased;

• a lower part (12) which forms the lower part of said boom (10), is formed by bending from at least 9 different bending points (14) determined at equal intervals, characterised in that the upper part is formed by bending from at least 5 different bending points determined at equal intervals.
The boom (10) according to claim 1 or 2, characterized by bending the middle of the 5 bending points (14) formed on said upper part (11) with γ bending angle; bending the bending points (14) at the edge with Ω bending angle; bending the remaining 2 bending edges (14) with θ bending angle.
The boom (10) according to claim 1 or 4, characterized by bending among the 9 bending points (14) formed on said lower part (11), the ones at the edge with α bending angle; bending 7 bending points (14) in the middle with β bending angle.
The boom (10) according to claim 3 or 5, characterized by;
• Bending the bending points (14) formed on said upper part (11) such that the angles of the same is from bigger to smaller one respectively γ, θ, Ω,

• Bending the bending points (14) formed on said lower part (12) such that β bending angle is bigger than γ bending angle.
A method of manufacturing the boom (10) according to claim 1, characterized by comprising of the following process steps;
• Forming said upper part (11) by bending the same from at least 5 different bending points (14) at equal intervals,

• Forming said lower part (12) by bending the same from at least 9 different bending points (14) at equal intervals,

• Mounting the weld grooves (13) of said upper part (11) and lower part (12) to each other.