NL2005077A - Self clamping lifting clamp. - Google Patents

Description

Self clamping lifting clamp

The invention relates to a self clamping lifting clamp for lifting objects, such as work pieces in the metal machining industry. It also relates to a method of lifting an object using such a clamp.

In the metal industry a lot of milling machines are used to work on work pieces to fabricate metal products such as a metal cylinder. Very often, the work pieces are relatively heavy and for one handcrafts man difficult to handle. To lift and move a heavy work piece, hoist clamps are used connected to a lifting device. The work piece is clamped into the hoist clamp and lifted to a certain height. Next the work piece is transported on or into a machine. Exact positioning of a heavy work piece can be very tricky and most often requires a lot of human muscle force. This may lead to dangerous situations and may result in injuries or damage to the work piece and/or machinery.

It is a goal of the present invention to provide a lifting clamp that can be used to transport and manoeuvre a work piece more easily than with the lifting clamps of the state of the art.

This goal is achieved by providing a self clamping lifting clamp comprising: - a first scissor halve and a second scissor halve pivotably connectable to the first scissor halve for forming a scissor mechanism; - a lifting member for providing a lift connection to the clamp; - a first hoisting member and a second hoisting member each movably connected with said handle and a first end of one of said scissor arms; - a first clamp member and a second clamp member; en - positioning means for, during a mutual scissor movement of the scissor halves, providing of a mutual positioning respective to each other of the clamp members.

Δη advantage of such a device according to the present invention is that grasping and/or manipulating or a weighty object can be achieved in a more convenient manner that in devices according to the state of the art, at least lacking mutual positioning of the clamp members.

In a first preferred embodiment, the device is arranged in a way in which the clamp members are each pivotably connectable to a second end of said respective first and second scissor halves. Such a pivotability provides a way of connecting the scissor halves with the clamping members in line with applying the positioning means.

In a particular embodiment, the first and second clamp members are connected with each other by means of an extendable bar construction, in such a way that the first and second clamp member are rotatable about substantially the same axis.

In an embodiment each of the first and a second grasp member comprises one or more deformable contact members. The advantage of a deformable contact member having a deformable contact surface, is the ability to make sufficient contact with non-flat surfaces.

In a further embodiment the contact members comprise rubber. Using rubber contact members will reduce the risk of damaging the object. Furthermore, a rubber contact surface results in good grip on the outer surface of the object to be lifted.

In an embodiment each of the scissor arms comprises a flat bar having a substantially straight upper section and a curved bottom section.

In an embodiment each of the grasp members comprises: - a first contact surface which makes an angle a with an axis of rotation of the grasp member; - a second contact surface which makes an angle β=-α with the axis of rotation of the clamp member, wherein - a is smaller than 90°, and preferably larger than 600.

By using contact surfaces that make an angle a with the axis of rotation, wherein a is smaller than 90°, the angle between the contact surfaces is less than 180°. If the angle a is less than 90° the clamp members are particularly suitable to grasp substantially tubular obj ects.

In a further embodiment, the extendable bar construction comprises a telescopic extension arranged in parallel with the axis of the first and second clamp member .

The invention also relates to a method of lifting an object, the method comprising; - position the object between a clamp according to any of the preceding claims, - lifting the object by exerting a tensile force onto the handle.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which corresponding reference symbols indicate corresponding parts, and in which: - Figure 1 shows a 3D view of a self clamping lifting clamp according to an embodiment of the invention; - Figure 2 shows a 3D view of the clamp of Figure 1 from a different perspective; - Figure 3 shows an object that is clamped using an clamp according to an embodiment; - Figure 4 shows some typical dimensions of the components of the clamp according to an embodiment.

Figure 1 shows a 3D view of a self clamping lifting clamp 1 according to a preferred embodiment of the invention. The clamp 1 comprises a first scissor arm 2 and a second scissor arm 3 that is pivotably connected to the first scissor arm 2 so as to form a scissor mechanism. A handle 4 is provided for raising the clamp 1 by means of for example a rope or a tackle. A first hoisting arm 5 and a second hoisting arm 6 are pivotably connected between the handle 4 and a first end of the scissor arms 2,3. At the other ends of the respective scissor arms 2,3, two clamp members 7,8 respectively, are pivotably connectable to the scissor arms 2,3. Furthermore a first and a second grasp member 9,10 are connected to a corresponding clamp member 7,8.

The grasp members 9,10 can be moved towards each other so as to grasp an object inserted between the first and second grasp members by exertion of a tensile force on the handle 4. This way of clamping is common for the state of the art scissor clamp lifting devices, as will be known by the skilled person. According to the invention, the grasp member 9,10 are rotatably connected to their clamp members 7,8. Once an object is clamped it can be rotated in the clamp for easy positioning and handling. This is particularly convenient when the object is a heavy working piece that needs to be positioned in or on a milling machine. Exact positioning is most often crucial and a hazardous task. By being able to rotate the object, the user is able to exactly position the object before the clamp is loosened and the object is freed.

In the embodiment of Figure 1, the clamp 1 comprises an extendable bar construction comprising a telescopic arm 14 and two connecting sections 15,16 for connecting the telescopic arm 14 to the clamp members 7,8. An telescopic arm 14 is easily extendable and has a simple and solid construction. The telescopic arm 14 will increase and decrease in length depending on the distance between the clamp members 7,8 defined by the size of the object (not shown) to be clamped. Due to the extendable bar construction, the clamp members 7,8 and thus the grasp members 9,10 are aligned. In this way the grasp members 9,10 will rotate about substantially the same axis. Furthermore, due to the alignment of the clamp members 7,8, on object is easily clamped without the need to manually align the clamp members 7,8 just before clamping. A further advantage of the extendable bar construction is that the object can be clamped more secure and the risk of the object falling out of the clamp is minimized.

In Figure 1 four contact members 17,18 are shown for making contact with the object. Preferably, the contact members 17,18 are deformable comprising deformable material such as rubber. Using deformable contact members increases the number of object that can be securely clamped. Rubber contact pads are preferable since rubber is a also very anti-slip.

In the embodiment of Figure 1, the scissor arms 2,3 comprise flat bars having a substantially straight upper section and a curved bottom section. Preferably, the arms 2,3 are made of stainless steel or iron. Such materials resist strong forces and result in a solid clamp. In the embodiment of Figure 1, the handle 4 comprises an opening 20 through which a rope or tackle can be pulled for lifting up the clamp 1. A hinge spindle 22 is provided to let the scissor arms 2,3 pivot.

Figure 2 shows a 3D view of the clamp 1 from a different perspective. In Figure 2 a grip 23 is shown which can be used by a user to grip and manoeuvre the clamp 1. The grip 23 is mounted on the hinge spindle 22. Also a latch 24 is provided to lock the clamp 1 in a open position, as will be known by the skilled person.

According to an embodiment, each of the grasp members 9,10 comprise a connection section, not shown in Figures 1 and 2, for rotatable insertion into the corresponding clamp member 7,8 respectively. Preferably, the grasp members 9,10 are replaceable so that different types of grasp members can be installed for lifting all kinds of objects.

Due to the extendable bar construction the first and second grasp members 9,10 are aligned along an axis 30, see Figure 2. This axis 30 corresponds to the axis of rotation of the object to be clamped.

The grasp members 9,10 may have a first arm 25 having a main axis that makes an angle a with the rotation axis 30 of the grasp member. A second arm 26 makes an angle β=-α with the main axis of the connection section.

In an embodiment, the angle a is smaller than 90°. Using such a configuration provides the possibility to clamp circular and/or tubular objects. Objects of different size can be handled without the need to change the grasp members .

By means of the invention, an object can be lifted and easily handled. First, the object is positioned between the clamp, and then by exerting a tensile force onto the handle, the object is clamped and can be lifted and transported. Figure 3 shows an object 40 that is clamped using a clamp according to an embodiment. Due to the arcuate shape of the extendable bar construction 14,15,16, the object 40 is free to move when rotating in the clamp 1. It should be noted that other extendable constructions are possible, such as variant using extendable, but non-telescopic arms.

Figure 4 shows some typical dimensions of the components of the clamp according to an embodiment. The values shown are mm. A typical weight of the clamp is 10 kg. Preferably, the axis a between the contact surfaces and the axis of rotation is larger than 60°, for example 75°. Other dimensions, angles and weights are used depending on the task.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described.

The descriptions above are intended to be illustrative, without limiting the scope of the annexed claims. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims (11)

Self-clamping hoisting clamp (1) comprising: - a first scissor half (2) and a second scissor half (3) pivotably attachable to the first scissor half (2) together forming a scissor mechanism; - an engagement member (4) for providing an engagement on the hoisting clamp (1); - a first lifting member (5) and a second lifting member (6), each of which is hingedly connected between the engagement member (4) and a first end of one of the scissors halves; - a first clamping member (7) and a second clamping member (8); and - positioning means for providing mutual positioning of the clamping members relative to each other during a mutual scissor movement of the scissor halves. Self-clamping hoisting clamp according to claim 1, wherein the clamping members are each hingedly connected to a second end of the first and second scissors halves respectively. Self-clamping hoisting clamp according to claim 1 or 2, comprising a first and second gripping member (9, 10) which are preferably rotatably connected to an associated clamping member. Hoisting clamp according to claim 1, 2 or 3, wherein the positioning means comprise an extendable rod construction (14, 15, 16), preferably such that the first and second clamping members are rotatable about substantially the same axis. Lifting clamp according to one or more of the preceding claims, wherein the clamping members are operatively movable towards each other such that an object (40) which can be placed between the first and second clamping member can be engaged when a tensile force is exerted on the engaging member (4), the object can be rotated together with the first and the second clamping member Self-clamping hoisting clamp according to one or more of the preceding claims, wherein each of the first and the second clamping member comprises one or more deformable contact members. A self-clamping lifting clamp according to claim 6, wherein the contact members comprise rubber. Self-clamping hoisting clamp according to one or more of the preceding claims, wherein each of the scissors halves comprises a flat rod with a substantially straight top part and a curved bottom part. Self-clamping hoisting clamp according to one or more of the preceding claims, wherein each of the clamping members comprises: - a first contact surface which makes an angle α with an axis of rotation of the clamping member; - a second contact surface which makes an angle β = -α with the axis of rotation of the clamping member, wherein α is less than 90 °, and preferably greater than 60 °. Self-clamping hoisting clamp according to one or more of the preceding claims, wherein the positioning means comprise a telescopic arm that runs parallel to an axis of rotation of the first and the second clamping member. A method for lifting an object, the method comprising steps for: - arranging the object between a lifting clamp according to one or more of the preceding claims, - lifting the object by exerting a pulling force on the engaging member.