KR20090118898A - Grapple tooth for crane-grab - Google Patents

Abstract

PURPOSE: A grapple tooth for a crane grab is provided to lengthen the lifetime of the tooth by preventing abnormal power from being applied on a joint part even in case the tooth is considerably worn away. CONSTITUTION: A grapple tooth for a crane grab is molded of materials having higher hardness than the material of a grapple and is welded on the grapple. A triangle flat blade(11) is formed throughout the upper side, the front side and the upper side corner of the tooth. A rib(12) protruded to the lower part of the flat blade is formed throughout the lower side and the lower side corner of the tooth. A supporting plane(14) delivered with action force by the grapple is formed throughout the rear side of the rib and the flat blade.

Description

Grapple tooth for Crane Grab {Grapple tooth for Crane-grab}

The present invention is a replacement type constituting the grapple (Grapple: tongs) end of the crane grab (crab tongs) used to bite or transport or load various types of scrap in the form of scrap, scrap materials, etc. It relates to the shape and material of the tooth and the method of joining.

The crane grab is a device that is mounted on a crane rope to bite and transport heavy and rough materials such as scrap metal, waste materials, and grain bags.

The general crane grab 100 as shown in Figure 1 is to grab the target by grabbing three to six grapples 20 attached to the main body, which is a part that directly digs into hard and rough materials such as scrap metal, grapple tooth. (10) is where the strong concentrated load acts. (Grapple tooth = meaning tooth for tooth, also known as tooth only for idiomatic expression.

Most of the crane grab 100 is the ground contact operation of the grapple 20, and the tooth 10 is worn most seriously during the abrasion process due to the shock contact due to the grasping operation and this portion (tooth) Wear rate often determines the overall service life of a crane grab.

2 is a structure of a conventional detachable grapple tooth that has been developed to cope with the wear of the tooth. 2, the pin-coupled tooth structure of the upper part is a grapple of the crane grab described in Korean Utility Model Publication No. 20-2008-0004188, which pins the replaceable tooth 10 to the grapple 20 to which the tooth adapter is welded. Tooth 10 will be replaced when worn or damaged.

The bolt fastening tooth structure at the bottom of FIG. 2 is a tooth device of the attachment for heavy equipment described in Korean Patent Publication No. 10-0897532. This tooth device is to be firmly fastened with four bolts after the tooth 10 is inserted into the grapple 20 formed with the bolt fastening hole and the fitting portion.

The structure of the above-described pin-coupled tooth is not easy to maintain the continuous strength of the coupling site due to the nature of the tooth that the strong and shocking force repeatedly acts. For example, the most common side effect due to a decrease in strength between the tooth and the grapple is that the tooth wobbles due to the clearance of the pin. This results in a large loss in the total amount of action and time of biting force in situations where the tip of the tooth is to dig or bite strongly. Because of the play between the tooth and the grapple, the grapple's sin cannot be effectively transmitted by the tooth to the object.

Another problem with a pin-toothed tooth is, for example, the strongest part of the overall structure of the grab is the tooth end. However, as shown in FIG. 2, the volume of the pin and the pinhole is smaller than the volume of the tooth. In this structure, considering the difference in wear rate according to the volume difference, a contradiction arises that the material forming the pin and pinhole must be stronger than the tooth. Otherwise, if the adapter, tooth, and pin are all made of ordinary steel, the pin must be designed to be over a certain volume, so the tooth must also be manufactured to a fairly large size. This means that the material of the replacement tooth alone already causes considerable material loss.

Therefore, considering the economic feasibility, it is more effective to form a new tooth by grinding the end of the grapple that is worn out and replacing the steel with a new one, rather than a replacement reinforced tooth considering the material loss.

The bolt-tooth type described below has the advantage that the strength of the binding force is small compared to the pin-tooth type tooth, and there is little loss of force, and there is almost no play during use, but the strongest part is not the tooth end but the head of the bolt. There is a limit. In the structure shown in FIG. 2, the head of the bolt is the smallest but exposed to severe wear. In other words, as in the case of the pin described above, there is a contradiction that the bolt must be a stronger material than the tooth. Moreover, in consideration of the conventional bolt volume and the material that can be manufactured, the tooth must also be manufactured in a considerably large size, and according to the nature of the grab work, the bolt head may be rapidly worn to such an extent that the bolt is hardly loosened.

As described above, the mechanical coupling between the tooth and the grapple may lead to excessive wear of an undesired portion or a play in the use environment of the product. Thus chemical bonding, ie welding, is a viable alternative, which also has some problems.

As will be described below, welding attaching an alloy steel of a less weldable reinforcement material to a conventional steel is not only complicated and difficult in the welding process itself, but also welded materials (for example, ordinary mild steel) to the welded portions. The reliability of the welding strength is inferior.

For example, a welded area between dissimilar metals may easily fall off when a shear force (slip due to torsion), a tension force (pull due to bending), etc., is applied, rather than a simple compressive force.

Therefore, the structure in which the reinforced material is welded to the grapple, which is a normal steel, in a conventional form, has a different direction of the force applied to the welded portion as the tooth wears, and thus the welded reinforcement is completely worn out before the tooth is welded. You can get out of the grapple. This is more economical than making a grapple with tooth formed of ordinary steel and welding and repairing additional steel as the tooth part wears.

In order to overcome the above disadvantages, simply increasing the total weld area between the tooth and the grapple, which are different materials, means an enlargement of the tooth, and thus there is no difference from the structural limitation of the mechanically coupled tooth.

In addition, the purchase cost and casting cost of the reinforced tooth material is a big burden, and the weight increase of the tooth portion adversely affects the overall performance of the crane grab.

The present invention is made of a reinforcing material, to effectively overcome the shortcomings of the long-term repeated use in the replaceable tooth attached to the grapple through a better weld structure and thus an optimal tooth shape.

To this end, cast steel was cast by high pressure by means of a mold to make a tooth, but the direction of the force acting on the tooth during the operation of the crane grab was analyzed, and accordingly, the occurrence of wear and the progress of wear of each part of the tooth were derived.

By intentionally changing the wear area of a specific part of the tooth through the area of occurrence and progression of derived tooth wear, the large area wears slowly and the small area wears quickly so that an optimal tooth wear pattern can be realized. have.

This prevents the wear of the tooth from going unintentionally, preventing the tooth from being able to dig into the target properly or, in the worst case, even broken before it wears out.

In addition, the present invention, in the process of welding and attaching the tooth to the grapple, the welding between the alloy cast steel and the general carbon steel should be made in a high temperature condition accompanied by preheating, in view of the fact that the welding between dissimilar metals is less reliable in the bonding strength, etc. In order to effectively dissipate the heat concentrated on the pointed part of the tooth, the part of the tooth inserted into the grapple is enlarged so that the weld face receives the least tensile or shear force.

The above structure is to prevent the welding joint surface from being destroyed when an unintended impact or overload is applied while the tooth is holding the target.

In the following detailed description of the invention a specific design follows.

Due to the unique tooth design structure of the present invention, the effect obtained is as follows.

First, the conventional reinforcement type reinforcement is the direction of the working load applied to the entire tooth as the wear progresses, which causes undesirable torsional or bending forces in the joint between the tooth and the grapple, According to the present invention, since the wear was intentionally designed to proceed differently on the upper and lower surfaces of the tooth, the abnormal force does not act on the joint even when the tooth is worn out considerably. As a result, the life of the tooth is increased.

Second, in the case of the conventional replaceable reinforced tooth, the bond strength with the grapple was dropped by a mechanical bonding method or an incomplete weld welding method, which was made due to the failure of the coupling part or the deterioration of the work performance of the entire crane grab. According to the design, it is possible to secure sufficient bonding strength even if the tooth of the reinforcing material is bonded.

Third, the durability is much superior to the conventional partially strengthened tooth and the weight does not increase much. In addition, it is proud of superior weld strength and light weight as compared to the conventional reinforcement tooth which is all-in-one, and in certain parts, it is possible to exhibit more excellent durability as the wear progresses. Therefore, it is possible to manufacture a crane grab that is not heavy and can be used for a long time while saving expensive casting material for reinforced tooth.

The main technical features of the present invention including the structure introduced in the above-mentioned problem solving means are as follows.

First, a triangular flat plate blade 11 is formed on the top, front, and side upper edges of the tooth 10, and ribs 12 protrude downward from the flat blade 11 over the bottom and side lower edges. ).

At this time, from the front to the rear of the tooth, the front cross-sectional area of the flat blade 11 is designed to be equal to or larger than the front cross-sectional area of the rib 12, so that the wear of the rib portion occurs more quickly. to be.

The tooth forms a support surface 14 over the rear face of the plate blade 11 and the rib 12 to receive force from the grapple.

In the inner surface of the back surface of the tooth 10, the insertion part 13 inserted into the grapple is formed long, and the insertion part 13 and the flat blade 11 and the rib 12 are adjacent to each other. Reinforcing ribs 15 are formed to enlarge the cross-sectional area in the front direction of the ribs 12.

The reinforcing rib 15 serves to stop abrasion of the fast-wearing rib 12 at a certain limit, and the insertion part 13 concentrates excessive heat on a sharply stepped support surface during a welding process including preheating. It is the role of distributing things.

In order to more specifically represent the main technical features of the present invention will be described in more detail below with reference to an example of the present invention included in the drawings.

However, in the specific example described below, the components including the specific technical terms and the specific coupling structure combining them with each other do not limit the idea inherent in the present invention.

3 and 4 illustrate the external shape of the tooth fabricated according to an embodiment of the present invention.

If the position of each tooth and each direction are defined in advance for convenience of explanation and clarity of rights, the side with the flat blade 11 corresponds to the upper surface, and the side with the rib 12 is provided. If, and the blade end of the tooth is the front, the side with the insertion portion 13 to be inserted into the grapple is the rear.

This example was made of cast steel added with chromium and molybdenum.

The type symbol of the cast steel is SCNCrM 2B, which is a cast steel for structural and steel materials of high stiffness, mainly used for machine tool spindles, hydraulic pistons, and camshafts.

Addition ratio range of added chemical components is 0.25 ~ 0.35% of carbon (C), 0.30 ~ 0.60% of silicon (Si), 0.90 ~ 1.50% of manganese (Mn), 0.040% or less of phosphorus (P), and 0.040% of sulfur (S) Based on the following steel, nickel (Ni) is added in the range of 1.60 to 2.00%, chromium (Cr) is added 0.30 to 0.90%, molybdenum (Mo) is added 0.15 ~ 0.35% to improve the mechanical properties It is commonly referred to as chromium-molybdenum steel.

The cast steel material as described above is relatively fragile because it cannot be forged / rolled, which is applicable to mild steel, but has a high tensile strength of 880 N / mm2 with a high hardness of more than 269 HB, which is the best among cast steels, through quenching / tempering heat treatment. It is humble. Therefore, with the exception of material cost and process cost, it is classified as the best material applicable to tooth.

The tooth of this embodiment can be cast in one step without undergoing a special finish surface by casting the material in a shell molding process. The shell molding process is a process of forming a mold by applying a shell material containing SiO 2 and a thermosetting resin to a tooth model made through a mold. In consideration of the strength of the shell, the tooth 10 of the crane grab having a weight of about 3 to 5 kg of the present embodiment is an optimal casting method having the best precision for the production cost.

The shell molding process can be precisely cast even by an unskilled worker if only the mold is designed, and it is difficult to apply because the casting becomes heavy more than the weight that a thin shell can handle even if it is too large than the size of this tooth. For example, in the bone tooth 10, even if only the inside of the ribs 12 is filled, the allowable load of the shell 10 kg is easily exceeded.

The cast steel 10 of the cast steel material as described above is welded with the carbon material of the grapple 20 because it is inferior in weldability and is bonded to the grapple by a preliminary welding process.

First of all, the metal-active gas welding mixed with argon and carbon dioxide (welding method with the gas mixture characteristic activating the welding surface in the welding atmosphere similar to conventional inert gas welding) Spot welding method).

After preheating the welding surface between the tooth 10 and the grapple 20 at a temperature of 210 ° C. or less (preferably 150 ° C. to 210 ° C.), the chemical properties of the welding surface are improved, and a wire welding rod (tensile strength of 60 kg or more) is used. The main welding according to the above-mentioned welding method is performed along the welding surface slightly joined by the temporary welding method.

At this time, the welding method first welds the short segment side of the tooth, that is, the left and right sides, and then welds the long segment side, that is, the upper and lower surfaces, next. The reason for this is welding in a high temperature environment and welding deformation easily occurs because both materials are different.

The shorter weld line is not much bent due to thermal deformation because the opposite support point (opposite short line segment) is far. Therefore, it is preferable that the shorter line segment is welded first to minimize the deformation of the attachment angle of the tooth. The reason for preliminary welding before the main welding is also largely intended to prevent deformation due to such bending.

The joining method is intentionally reflected in the design of the tooth 10 of the present invention. For example, in FIGS. 3 and 4, the circumference of the support surface 14 corresponds to a welding area between the tooth 10 and the grapple 20.

The support surface 14 is a portion that directly transmits a large force of the grapple to the tooth, so that the stepped protrusion is small and sharp. When this part is heated, local thermal stress is generated, and as the temperature rises, the mechanical properties are deteriorated by local overheating, so it is necessary to quickly remove heat to the surroundings. To this end, the insertion part 13 is formed to be somewhat longer in order to make the heat dissipation direction in one more direction. In FIG. 4, the length of the insertion part 13 extending backward is 45.5 mm, and the rib 12 extends downward. Is longer than the height of 37.34mm. Therefore, the welding area near the support surface 14 can transmit heat in all three directions to the left, right, and bottom of the welding line.

Referring to the tooth 10 shown in the drawing, a flat blade 11 having a sweepback angle 111 of 57.3 ° is formed on an upper surface thereof, and a receiving angle of 10 ° and 18 °, respectively, in the front and side directions on the lower surface thereof ( Ribs 12 are formed with angles of attack 121, 122.

The flat shape of the upper blade minimizes the scratching distance when digging scrap such as scrap metal, and thus reduces wear than the streamlined shape. The retreat angle and the receiving angle reduce the resistance during the movement of the tooth like the wing of an airplane, and at the same time, ribs It is a design factor that acts as a variable on the amount of cross-sectional area change due to the wear of the and flat blades.

In the drawing, the overall tooth 10 size of the embodiment is 198.16 mm in total length, 171.61 mm in total width, and 53.34 mm in total shape of a large triangular wing, considering the specific gravity of the classification code SCNCrM 2B chromium-molybdenum steel, the size of which weight is important. Therefore, it can be seen that the reinforcing ribs 15 are formed only at the depth of the two rows of ribs 12 extending laterally and the tooth is almost worn out.

As the weight of wheels and tires, which are distal ends, plays an important role in the overall performance of a vehicle, the crane grab 100 to which the present invention is applied is a device that works by hanging on a string, so that even a small amount of weight is cumulative in a long time repetitive work. Has Therefore, the tooth shape of the present invention having a slim shape compared to the conventional replaceable reinforced tooth has an important technical and economic meaning.

In the drawing, the flat blade 11 protrudes about 10 mm from the grapple and the extended working surface (inner clip), which plays an important role in reducing the wear of the inner surface of the grapple.

In addition, as will be described further below, the shape of the thinly formed ribs 12 plays an important role not only in reducing the total weight of the product, but also in overall equal wear.

5 shows a state in which a tooth is mounted on a crane grab according to the present embodiment, and FIG. 6 shows a progress pattern of wear in a state in which the tooth is welded to the grapple. As shown by the blue dotted line in FIG. 6, the wear of the tooth is displayed in an intuitively intuitive pattern according to the working direction, but if it is looked at in detail, the upper surface, which is a side that penetrates and lifts the target, receives more load than the lower surface. As a result, the top surface will wear more.

7 is a diagram showing the difference in the wear cross-sectional area of the upper substructure during the wear progress of the tooth of the present invention, looking at the drawing flat plate 11 has a thin and wide wear surface is formed (area painted in blue), ribs At 12, two wear surfaces having a thick thickness and a narrow width are formed. (Area painted in red).

If the area of blue is smaller than the area of red, the blue wear surface will wear out faster as a result. This is undesirable as a wear pattern throughout the tooth. This is because the lower red wear surface must be worn the same or faster than the blue wear surface so that the blade tip of the tooth 10 can be kept in a sharp blade shape. Therefore, the blue area must be equal to or greater than the red area.

To this end, digging the ribs 12 in two to help not only reduce the overall tooth weight but also help to form an effective wear pattern.

Although the figure shows an oblique curved surface, which is the actual wear occurrence pattern, it is not easy to calculate such a complex wear surface in all layers in the actual design process and reflect it in the rib 12 design. effective. This refers to designing the front cross sectional area of the flat blade 11 in the specific cross section from front to back of the tooth 10 to be equal to or larger than the front cross sectional area of the rib 12.

8 is a diagram illustrating a wear and break pattern of the conventional replaceable reinforced tooth and the present invention tooth.

The tooth of the present invention can remove a worn tooth and attach a new tooth by slightly melting and digging the welded portion like other replaceable reinforced tooth. This is known as gouging in the art, and it is possible to remove the tooth without affecting the grapple body by melting and dividing the weld with a small spark. Of course, this replacement process should only be applied to a completely exhausted tooth, so it's worth mentioning that it is economical.

If the joined tooth or the flat blade 11 portion of the tooth falls off before it is completely worn, this is not only a great waste, but also affects the joint structure of the grapple 20 in the process of bending away. Referring to the drawings, the top tooth is attached only the flat blade 11 up and down. This structure causes irregular wear and at some point the upper blade (the blade with the greater force) can be severely sheared off. This possibility is further amplified by the less worn lower blade.

The middle tooth is a triangular pyramid of the whole blade 11. Again, as described above, the force exerted obliquely on the upper side of the tooth in the working direction is greatest, and thus the upper portion of the tooth wears a little more. When the deformed wear accumulates, the blade tip direction of the tooth is slightly bent downward so that the upper part of the tooth is exposed to a larger load, and if this phenomenon is steadily progressed, the whole 11 is momentarily broken.

The bottom tooth is a tooth according to the present invention, and the wear rate of the rib 12 is faster than the rate at which the flat blade 11 is worn. Therefore, when viewed from the side, the thin plate blade 11 and the thick rib 12 wear together. This provides a condition for using the tooth to the point where the reinforcing rib 15 is formed without any problem, and when the resistance to the entire grapple 20 increases due to wear to the point of the reinforcing rib 15, then the tooth is considered to be replaced. You can try

While the embodiments of the present invention have been described in detail with reference to the drawings, the technical spirit of the present invention is not limited to the above embodiments.

In other words, one of ordinary skill in the art to which the present invention pertains may utilize the technical configuration described in the detailed description or drawings of the present invention to further implement a simple modification and simple extension design as necessary. It is also obviously included in the scope of the technical spirit inherent in the present invention.

1 is a view showing the structure of a typical crane grab.

Figure 2 is a view showing the structure of a conventional detachable grapple tooth.

Figure 3 is an external perspective view of the present invention tooth.

Figure 4 is a view of the invention tooth in the up, down, left, and right sides.

Figure 5 is a view mounted to the crane grab the present invention tooth.

Figure 6 is a diagram showing a progress pattern of wear in the present invention the tooth is welded to the grapple.

Figure 7 is a diagram showing the difference in wear cross-sectional area of the upper substructure during the wear progress of the present invention tooth.

8 is a diagram illustrating a wear and break pattern of the conventional replaceable reinforced tooth and the present invention tooth.

* Explanation of the reference numerals for the main parts of the drawings

100: crane grab = crane tongs or scrap metal tongs

20: Grapple (Grapple = claw or tong leg)

10: Tooth (tooth teeth)

11: plate blade 12: rib (rib = protrusion reinforcement part)

13: insert 14: support surface

15: Reinforcement Rib

111: Sweepback angle of flat blade

121: Rib front angle of attack

122: Rib inner side angle of attack

Claims (6)

In a tooth that is cast with a material having a hardness higher than that of the grapple 20 of the crane grab 100, and welded to the grapple 20, A triangular flat plate blade (11) is formed over the top, front, and side edges of the tooth; A rib 12 protruding downward of the plate blade 11 over the bottom and side lower edges of the tooth; Tooth (10), characterized in that the support surface (14) is formed to receive the action force from the grapple (20) over the back of the plate blade (11) and the rib (12). The method of claim 1, Tooth (10), characterized in that from front to back of the tooth (10), the front cross-sectional area of the plate blade (11) is equal to or greater than the front cross-sectional area of the rib (12). The method of claim 2, An insertion part 13 inserted into the grapple 20 is formed on a rear surface of the tooth 10; Tooth 10, characterized in that the reinforcing rib 15 to enlarge the cross-sectional area in the front direction of the rib 12 is formed in the position where the insertion portion 13, the flat blade 11 and the rib 12 are adjacent to each other. ). The method of claim 3, Tooth (10), characterized in that the insertion portion (13) extends to a length greater than the height of the rib (12) behind the support surface (14). The method of claim 1, Tooth 10 is a tooth 10, characterized in that the chromium (Cr) is made of steel (steel) added 0.30 ~ 0.90% by weight, molybdenum (Mo) 0.15 ~ 0.35% by weight. The method of claim 1, The tooth (10) is a tooth (10), characterized in that produced by the shell molding process (Shell Molding Process).

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