Patent Description:
There are a plurality of different loads and load types, which are usually handled in warehouses and factories by clamping the loads from their sides. The handling of these kind of loads is typically done with a clamp device connected to a lift truck or other type loader. Typical examples of these kinds of loads are paper rolls and material bales. Similar kind of load handling with clamps or clamping devices is also used in handling of loads packed in boxes, such as home appliances and consumer electronics.

Load handling with clamping typically requires, that the clamp or clamping device is adapted suitable for the dimensions, type, weight, shape and selected handling method of the load. For adapting the clamp or clamping device suitable for the dimensions of the load, different frame and arm combinations are used. All of these different combinations typically comprise a contact surface or clamping surface suitable to the load in question, which surface can be a separate part or integral part of the arm. Also, if more than single load is to be simultaneously handled, the clamping device needs to have arm structure or construction suitable for that purpose. For example, when a plurality of paper rolls is handled simultaneously, the clamp structure is typically divided to a plurality of sections so that it can used to clamp and handle a plurality of rolls with different diameters at the same time.

The challenge with the load handling utilizing clamping is that the dimensions and weights of the loads typically vary much, and due to the demands set by the storage facilities the loads must often be stacked to very high stacks. This makes the work of the operator of the truck, especially with manually driven trucks, very demanding since the visibility to the load and to the contact surfaces is typically often very restricted, especially when the load is loaded or stacked high. This problem is even greater with clamps having asymmetric clamping arms, i.e. one arm is longer than the other.

This visibility problem may lead to accidents if the operator of the loader fails to open the arms of the clamp sufficiently during releasing of the load before starting to move the loader itself.

Publication <CIT> discloses a method according to the preamble of claim <NUM>, and, respectively, a roll clamp apparatus attached to a forklift, which apparatus comprises two arms with contact surfaces for contacting substantially opposite side surfaces of the roll, which arms are movable in relation to each other for obtaining the clamping and release operations for the roll. The apparatus also comprises detection means for obtaining coordinate information of the outer periphery surface of the roll.

Publication <CIT> discloses drum lift indicators and inventory control devices for use with drum handling devices, which provide signals indicative of whether drums are properly clamped in the drum lifting equipment.

Publication <CIT> discloses barrel drum transporter that can be used to move a drum from a first bed at a first location to a second bed at a second location, which drum transporter is operable to grab the drum during the transport operation.

Publication <CIT> discloses interactive clamp force control system for load handling clamps.

The present invention provides a novel solution for overcoming the above discussed problems.

In the present invention the operator of the loader with a clamping device is informed when the arms of the clamp are sufficiently detached from the load during release of the load, so that the operator knows when the loader can be safely moved.

In the method of the invention for handling loads with a load handling device connected to a loader, which load handling device comprises at least two arms with clamping surfaces for contacting opposite side surfaces of a load and wherein at least one of the at least two arms is movable in relation to the other arm for obtaining the clamping and release operations for the load, when the load is clamped between the clamping surfaces the distance and/or position of the arms in relation to each other or in relation to the handled load is defined, and during releasing of the load the movement and/or position of the arms in relation to each other or in relation to the handled load is measured, and once defined distance and/or position between the arms or in relation to the handled load is reached, a signal indicating safe movement of the loader is issued.

In an embodiment of the method of the invention the position of the arms when the load is clamped between the contact surfaces is detected and the clamping position of the arms is defined based on this detection. The detection of the clamping position of the arms can be based on pressure rise in the hydraulic circuit operating the arms, for example, or with other suitable means and ways. The detection of the clamping position of the arms, i.e. that the load has been clamped between the arms, can also be indicated to the operator of the loader with suitable light and/or sound alarm, for example.

In an embodiment of the method of the invention the position of the handled load in relation to the arms is defined, and the distance and/or position between the arms or in relation to the load is defined based on the position information of the handled load. In this embodiment the position of the handled load in relation to the arms preferably comprises measurement of the distance of the surface of the load from a frame part to which frame part at least one of the at least two arms is turnably connected.

In an embodiment of the method of the invention the indication signal is a sound and/or light signal.

In an alternative embodiment of the method of the invention the indication signal is a data transfer to other system, such as an external system and/or controller for example, through a dedicated data communication bus, or other digital or analog signal. This data transfer can be used for enabling the use of additional external sensors on the loader to check the surroundings while backing off from the load, and/or visually displaying the clamp and loader positions during backing off from the load, for example.

More precisely the features defining a method in accordance with the present invention are presented in claim <NUM>. Dependent claims present advantageous features and embodiments of the invention.

Exemplifying embodiments of the invention and their advantages are explained in greater detail below in the sense of example and with reference to accompanying drawings, where.

<FIG> shows schematically a loader <NUM> with a load handling device as a top view, which load handling device is a clamping device <NUM>. The clamping device <NUM> comprises two arms 3a and 3b, which are connected turnably to the frame part <NUM> of the clamping device. At the ends of the arms 3a, 3b are contact surfaces 4a, 4b via which the clamping device contacts the load to be handled.

The clamping device <NUM> shown in <FIG> is configured for handling paper rolls, which typically needs to gripped and handled both on horizontal and on vertical orientation, and turned between these orientations. Due to the need of lifting rolls in horizontal orientation from ground and for turning them in vertical orientation for storage, the arm 3a of the clamping device is longer than arm 3b, and the frame part <NUM> is rotatable in relation to the loader <NUM> for changing the orientation of the arms 3a, 3b and the load clamped between the arms. However, the arms 3a and 3b may be substantially equally long.

<FIG> shows schematically an embodiment of a load handling device of the present invention, which is a clamping device <NUM>. As discussed in relation to <FIG>, the clamping device <NUM> comprises two arms 3a and 3b, which are connected turnably to the frame part <NUM> of the clamping device. At the ends of the arms 3a, 3b are contact surfaces 4a, 4b via which the clamping device contacts the load to be handled.

In addition to the general parts discussed above, the clamping device <NUM> comprises a signal light 8a located at least on the arm 3a, position sensors 8b for defining the positions of the arms 3a and 3b, and a load detecting sensor 8c for detecting presence of a load and for defining distance from a surface of the load to the front surface of the frame part <NUM>. In relation to the embodiment of <FIG>, wherein is disclosed position sensors 8b for both of the arms, only single position sensor may also be used, preferably for the longer arm 3a. Alternatively, the signal light 8a may be replaced with any other type signal (such as sound, vibration or data transfer) creating device, or with a combination of these, in the solution of the present invention.

<FIG> illustrates schematically an embodiment of the operation of the present invention.

<FIG> shows the situation, where a load <NUM> is clamped between the contact surfaces 4a, 4b of the arms 3a, 3b of the clamping device <NUM> of a loader. The load <NUM> is transferred to a defined place for storage, for example, and the operator of the loader start to release clamping of the load. In this embodiment the load <NUM> is a relatively small diameter paper roll, for example.

In the releasing of the load <NUM> the operator of the clamping device <NUM> moves the arm 3a away from the load and this way releases the grip between the contact surface 4a and the load. It is to be noted, that mere detachment of the contact surface 4a is not sufficient for safe movement of the loader equipped with the clamping device <NUM>, since the contact surface 4a would still be located behind the load <NUM>, as can be seen from <FIG>. Moving of the loader in this situation would lead either tipping or dropping of the load <NUM>, or, in case of heavy loads, tilting or falling of the loader.

In the present invention the position of the arms 3a, 3b is defined with position sensors 8b when the arms are gripping the load <NUM>. Further, the distance of the closest surface of the load <NUM> is also defined with the distance sensor 8c. Position of the load <NUM> is then defined from the position of the arms 3a, 3b, geometry of the arms, and distance measurement from the distance sensor 8c. And based on the stored zero point and position of the arms 3a, 3b, the release position of arm 3a is calculated. In the calculated release position the arm 3a is located sufficient distance away the load <NUM> so that the contact surface 4a, as well as other parts of the arm 3a, cannot hit the load when the loader equipped with the clamping device <NUM> is moved away from the load.

In the embodiment of the <FIG>, when release of the load <NUM> is started, and the arm 3a starts to move away from the load from the zero point, i.e. the position shown in <FIG>, the signal light 8a starts to blink to indicate that movement of the loader with the clamping device <NUM> is not allowed. Once the arm 3a reaches the position shown in <FIG>, the blinking of signal light 8a stops, which indicates to the operator that it is safe to move the loader from the load <NUM>. In this position of arm 3a, the color of the signal light 8a may also change, and different sound alarm may be issued.

<FIG> illustrates schematically an alternative embodiment of the operation of the present invention. In this embodiment the handled load <NUM> is relatively large diameter paper roll, for example.

Similarly than with the embodiment of <FIG>, <FIG> shows the situation, where a load <NUM> is clamped between the contact surfaces 4a, 4b of the arms 3a, 3b of the clamping device <NUM> of a loader and the load is ready to be released, and <FIG> shows the position of the arms 3a, 3b of the clamping device <NUM> for safe movement of the loader when the releasing of the load <NUM> is completed.

The actual release procedure is the same than disclosed in relation to the embodiment of <FIG>.

<FIG> shows a functional diagram of a basic embodiment of a system in accordance with the present invention.

The operator of the loader activates the system, as indicated in <NUM>, when a clamped load is ready to be released. First the system detects that there is a clamped load between the arms 3a, 3b of the loader, as shown in <NUM>, based on information obtained from the position sensors 8b and distance sensor 8c, for example.

When the clamped load is detected, the indicators, such as the signal light 8a, are turned on, as shown in <NUM>. Then the position of arms 3a, 3b is stored as shown in <NUM>, and moving of the arms for releasing the load can be started.

The position of arms 3a, 3b is followed and defined, as shown in <NUM>, with position sensors 8b. When the safe position of the arms 3a, 3b, is reached, as shown in <NUM>, indicators are turned off, as shown in <NUM>, which indicates to the operator that the loader can be safely moved away from the load, and the system returns to wait for a new activation.

<FIG> shows a functional diagram of an advanced embodiment of a system in accordance with the present invention.

When the system of <FIG> is activated, as shown in <NUM>, either manually by the operator of a loader or automatically by suitable signal or operation, the system proceeds to a short wait, as shown in <NUM>, before proceeding to load detection as shown in <NUM> and <NUM>. The load detection in <NUM> and <NUM> is based on input from distance sensor 8c, for example. Once the load is detected, the system proceeds measure arm positions as shown <NUM>. The load gripping is confirmed with a pressure measurement from a hydraulic system moving the arms of the loader, as shown in <NUM>, and the position of arms is updated, if necessary, based on the pressure measurement, as shown in <NUM>.

Once the gripping of a load is confirmed, the system proceeds to turn on indicators, such as the signal light 8a, indicating that the release of the load can be started, as shown in <NUM>. Further, the arm positions in gripping position, i.e. the zero point, are stored, as shown in <NUM>.

Based on the arm positions stored in <NUM>, the system defines the value Z1, which presents the required movement of arms to move them to safe position or point for moving the loader away from the load, as shown in <NUM>.

Next the operator can proceed to move the arms to release the load until the value Z1 is exceeded, as shown in <NUM>-<NUM>. Then the operator is allowed to start to move the loader from the released load, which is followed by the system, as shown in <NUM>, until the load has sufficiently far away from the load, that there is no risk of arms colliding the load. After this distance is achieved, the indicators are turned off, as shown in <NUM>, which indicates that the loader can be freely guided to a new load.

After the indicators are turned off, the system returns to the short wait, as shown in <NUM>, and proceed to the load detection cycle shown in <NUM> and <NUM> until a load is again detected at close proximity and gripped by the arms of the loader. This allows the system to be continuously in operation and does not need to be actively started again each time a load is to be released.

In relation to the present invention is it to be noted that the solution of the present invention does not require precise measurement of the load itself or the position of the contact surfaces contacting the load for providing the sufficient clearance of the arms and contact surfaces contacting the load. Thus, the required electronics and controlling methods can be implemented in much simpler way and economically advantageously than solutions requiring exact position definition of those.

Claim 1:
Method for handling loads (<NUM>, <NUM>) with a load handling device (<NUM>) connected to a loader (<NUM>), which load handling device comprises at least two arms (3a, 3b) with contact surfaces (4a, 4b) for contacting substantially opposite side surfaces of a load and wherein at least one of the at least two arms (3a) is movable in relation to the other arm (3b) for obtaining the clamping and release operations for the load, wherein when the load (<NUM>, <NUM>) is clamped between the contact surfaces (4a, 4b) the distance and/or position of the arms (3a, 3b) in relation to each other or in relation to the handled load is defined, characterized in that during releasing of the load the movement and/or position of the arms in relation to each other or in relation to the handled load is measured, and once defined distance and/or position between the arms or in relation to the handled load is reached, a signal indicating safe movement of the loader (<NUM>) is issued.