Device for measuring a load at the end of a rope wrapped over a rod

• US 8,209,096 B2
• Filed: 09/13/2009
• Issued: 06/26/2012
• Est. Priority Date: 05/19/2006
• Status: Active Grant

• Current Assignee: Joy Global Surface Mining Inc. (Mitsui & Company Limited)
• Original Assignee: Harnischfeger Technologies Inc. (Mitsui & Company Limited)
• Inventors: Claxton, Richard L.
• Primary Examiner(s): Nguyen, Cuong H
• Application Number:
  US12/558,533
• Publication Number:
  US 20100010714A1
• Time in Patent Office: 1,017 Days
• Field of Search: 701/50, 702/42, 738/624.74, 738/624.73, 738/624.6, 37395-396, 172/2
• US Class Current: 701/50
• CPC Class Codes: E02F 3/30 with a dipper-arm pivoted on a cantilever beam , i.e. boom
• CPC Class Codes: E02F 9/006 Pivot joint assemblies in general F16C11/04
• CPC Class Codes: E02F 9/24 Safety devices , e.g. for preventing overload E02F9/226 takes precedence
• CPC Class Codes: G01G 19/18 having electrical weight-sensitive devices
• CPC Class Codes: G01G 23/01 Testing or calibrating of weighing apparatus
• CPC Class Codes: G01G 3/141 the supports being disc or ring shaped
• CPC Class Codes: G01L 5/101 using sensors inserted into the flexible member

Abstract

A machine for raising and lowering a load, the machine including a platform, a boom attached at one end to the platform, a rod mounted transverse to the longitudinal axis of the boom on the other end of a boom, the rod having a central bore there through, with at least two strain gauges mounted therein and angled relative to each other, a hoist rope extending over the rod and having an end adapted to be attached to the load, and a mechanism connected to the at least two strain gauges for determining the angle of departure of the hoist rope from the rod and the amount of pull of the load on the hoist rope.

Claims

1. A method of determining a crowd length offset for a shovel including a base, a dipper, a boom pivotally mounted on the base, a hoist rope extending from the base to the dipper and wrapped over a sheave mounted on the end of the boom, and a dipper arm supporting the dipper on an end thereof, the dipper arm being pivotally mounted on the boom, a crowd resolver mounted on the boom and responsive to record an arm extension and retraction reading, where arm length is equal to arm offset plus arm gain times the crowd resolver reading, the method comprising:

automatically recalibrating a dipper position information,

storing maximum values of the crowd resolver,

using the known length of the arm at maximum extension positions, calculate offset value for each resolver maximum value,

obtaining an array of readings from the crowd resolver to calculate an array of calculated rope wrap angles,

obtaining an array of rope wrap angles from another device for measuring the rope wrap angles, and

selecting the crowd length offset that minimizes a difference between the two sets of calculations.

2. A method in accordance with claim 1 wherein said crowd length offset is selected by minimizing the square of the differences between the two sets of values.

3. A method in accordance with claim 2 wherein said crowd length offset is selected by using nonlinear programming to determine the offset value that minimizes the difference between the calculated rope wrap angles from the resolver data and the calculated rope wrap angle from the other device for measuring the rope wrap angles.

4. A method of determining a crowd length offset for a shovel including a base, a dipper, a boom pivotally mounted on the base, a hoist rope extending from the base to the dipper and wrapped over a sheave mounted on the end of the boom, and a dipper arm supporting the dipper on an end thereof, the dipper arm being pivotally mounted on the boom, a crowd resolver mounted on the boom and responsive to record an arm extension and retraction reading, where arm length is equal to arm offset plus arm gain times the crowd resolver reading, a hoist resolver mounted on the shovel and responsive to record hoist rope extension and retraction reading, where a hoist rope length is equal to a hoist rope offset plus a hoist rope gain times said hoist rope resolver reading, the method comprising:

automatically recalibrating a dipper position information,

obtaining a hoist rope wrap angle from a device for measuring the rope wrap angle, and

using the rope wrap angle, together with a known length of the boom between the dipper arm and the end of the boom, and the length of the hoist rope between the end of the boom and the dipper calculated using the hoist rope resolver, to calculate a length of the dipper arm and the crowd length offset.

5. A digging machine comprising:

a base;

a dipper;

a boom pivotally mounted on the base;

a sheave mounted on an end of the boom;

a hoist rope extending from the base to the dipper and wrapped over the sheave;

a dipper arm supporting the dipper, the dipper arm being pivotally mounted on the boom;

a crowd resolver mounted on the boom and responsive to record an arm extension and retraction reading, where an arm length is equal to an arm offset plus an arm gain times said crowd resolver reading;

a hoist resolver mounted on the shovel and responsive to record a hoist rope extension and retraction reading, where a hoist rope length is equal to a hoist rope offset plus a hoist rope gain times said hoist rope resolver reading;

a central processing unit including a software and a memory, the central processing unit connected to the resolver and configured to;

automatically recalibrate a dipper position information,

obtain a hoist rope wrap angle from a device for measuring the rope wrap angle, and

use the rope wrap angle, together with a known length of the boom between the dipper arm and the end of the boom, and the length of the hoist rope between the end of the boom and the dipper calculated using the hoist rope resolver, to calculate a length of the dipper arm and a crowd length offset.

6. A digging machine comprising:

a base;

a dipper;

a boom pivotally mounted on the base;

a sheave mounted on an end of the boom;

a hoist rope extending from the base to the dipper and wrapped over the sheave;

a dipper arm supporting the dipper, the dipper arm being pivotally mounted on the boom;

a crowd resolver mounted on the boom and responsive to record an arm extension and arm retraction reading, where an arm length is equal to an arm offset plus an arm gain times said crowd resolver reading;

a central processing unit including a software and a memory, the central processing unit connected to the resolver and configured to;

automatically recalibrate a dipper position information,

store maximum values of the crowd resolver,

use the known length of the arm at maximum extension positions to calculate the offset value for each resolver maximum value,

obtain an array of readings from the crowd resolver to calculate an array of calculated rope wrap angles,

obtain an array of rope wrap angles from another device for measuring the rope wrap angles, and

select a crowd length offset that minimizes a difference between the two sets of calculations.

7. The digging machine of claim 6, wherein said crowd length offset is selected by minimizing the square of the differences between the two sets of values.

8. The digging machine of claim 7, wherein said crowd length offset is selected by using nonlinear programming to determine the offset value that minimizes the difference between the calculated rope wrap angles from the resolver data and the calculated rope wrap angle from the other device for measuring the rope wrap angles.