Procedure and apparatus for the handling of loads

• US 5,292,219 A
• Filed: 05/06/1992
• Issued: 03/08/1994
• Est. Priority Date: 02/23/1990
• Status: Expired due to Term

• Current Assignee: Auramo Oy (Nacco Industries Incorporated)
• Original Assignee: Auramo Cargo Systems OY
• Inventors: Haapasalo, Pertti, Merin, Peter
• Primary Examiner(s): Bucci, David A.
• Assistant Examiner(s): KEENAN, JAMES W
• Application Number:
  US07/879,851
• Time in Patent Office: 671 Days
• Field of Search: 414/618, 414/619, 414/621, 414/730, 414/786, 414/910, 414/911, 414/607, 294/88, 294/907, 901/33
• US Class Current: 414/621
• CPC Class Codes: B25J 13/083 fitted with slippage detectors
• CPC Class Codes: B66F 9/184 Roll clamps
• CPC Class Codes: Y10S 294/907 Sensor controlled device
• CPC Class Codes: Y10S 414/124 Roll handlers

Abstract

Procedure and apparatus for the handling of loads using jaws pressed against the sides of the load. In the procedure of the invention, the slippage between the load and the jaws is measured and the compressive force of the jaws is adjusted on the basis of the slippage. The slippage is measured at least during a preliminary lifting performed before the load is lifted or at the beginning of the lifting operation. During the preliminary lifting the load can be lifted at an essentially lower speed than during the main lifting operation. The compressive force is increased during the preliminary lifting from a predetermined precompression value to at least a value at which the slipping ceases.

Claims

1. Gripper for a fork-lift truck for handling paper rolls, the gripper comprising a lifting device with which at least one roll can be lifted by at least one lifting cylinder, operating by means of a working fluid, and jaws closed to grasp said at least one roll by at least one compression cylinder, operating by means of a working fluid, the gripper further comprising:

at least one measuring device for measuring continuously the slippage between said at least one roll and the jaws;

at least one pressure sensing device for measuring the pressure of a working fluid flowing into said at least one compression cylinder producing a compressive force; and

a control unit for controlling said at least one lifting cylinder to lift the jaws with said at least one roll, after the compressive force reaches a predetermined precompression value, and for increasing the compressive force in a continuum from the predetermined precompression value, to a value at which there is no slippage between said at least one roll and the jaws;

wherein the device measuring the slippage is a pulse counting device and is so mounted on a jaw flap at the end of a jaw that it comes into contact with said at least one roll;

wherein the compressive force is increased from the predetermined precompression value in proportion to the amount of slippage measured by the measuring device;

wherein the gripper is provided with at least one valve which admits a small flow of working fluid into the lifting cylinder to facilitate a preliminary lifting operation; and

wherein the gripper is provided with a pressure limiting valve to limit the pressure of the working fluid admitted into said at least one compression cylinder once slippage between said at least one roll and the jaws ceases.

2. The gripper according to claim 1, further comprising a manual control device by which the operator may start and end the compression stage, and an indicator device for indicating the end of the compression stage.

3. The gripper according to claim 1, wherein the slippage measuring device has a roll type configuration and is capable of measuring the slippage of said at least one roll.

4. The gripper according to claim 3, wherein the slippage measuring device is a pulse transducer provided with a roller, wherein said roller rotates on an axle and contacts said at least one roll by a spring, wherein said pulse transducer measures relative movement between said roller and said roll in terms of a pulse count.

5. The gripper according to claim 1, wherein the slippage measuring device is placed in the middle of the flap of the jaws.

6. The gripper according to claim 1, wherein said working fluid further comprises a hydraulic fluid, and wherein said at least one compression cylinder further comprises at least one hydraulic cylinder.

7. The gripper according to claim 1, wherein said working fluid further comprises pneumatic air and wherein said at least one compression cylinder further comprise at least one pneumatic cylinder.