Apparatus for applying a load to a strain gage transducer beam

• US 4,411,327 A
• Filed: 05/14/1981
• Issued: 10/25/1983
• Est. Priority Date: 05/14/1981
• Status: Expired due to Term

• Current Assignee: Hottinger Baldwin Measurements, Inc. (Spectris PLC)
• Original Assignee: Hottinger Baldwin Measurements, Inc. (Spectris PLC)
• Inventors: Lockery, Harry E., Laimins, Eric
• Primary Examiner(s): Miller, Jr., George H.
• Application Number:
  US06/263,505
• Time in Patent Office: 894 Days
• Field of Search: 177/211, 177/DIG. 9, 308/6 R
• US Class Current: 177/211
• CPC Class Codes: G01G 21/23 Support or suspension of weighing platforms G01G21/24 takes precedence
• CPC Class Codes: G01G 3/1402 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: Y10S 177/09 Scale bearings

Abstract

In a platform scale in which the strain gage transducer beams are preferably formed as an integral part of a platform it is important that any distortions such as horizontal or angular force components that could falsify the reading of the weight, are prevented from affecting the transducers. For this purpose, the vertical load or weight representing force components are transmitted to each strain gage transducer beam through at least two cooperating curved, preferably spherical, surfaces. One curved surface has a larger curvature than the other so that a sufficient motion in any horizontal direction is permitted. The horizontal yielding prevents the transmission of a horizontal or angular force component to the sensing strain gages of the respective transducer beam but does not adversely affect the vertical force transmission to the transducer beams.

Claims

1. An apparatus for applying a load to a strain gage transducer beam in a platform scale, comprising first platform means (1), strain gage transducer beam means (3) forming integral components of said first platform means (1), second platform means (13) arranged above and substantially in parallel to said first platform means (1), force transmitting bar means (8), connecting means located between said first and second platform means for operatively securing said force transmitting bar means to the respective integral transducer beam means (3), first curved surface means (23) including at least one cup having a depression having a given radius of curvature, said cup being arranged between said first and second platform means, second curved surface means (24) including a ball having a radius of curvature smaller than said given radius of curvature of said depression, said second curved surface means (24) also being arranged between said first and second platform means for contacting said depression in said first curved surface means, and means operatively securing said cup to one of said platform means for cooperation with the ball for transmitting vertical force components effective on said second platform means (13) through said force transmitting bar means to said transducer beam means, said first and second curved surface means further cooperating for substantially freely yielding to any horizontal or angular force components effective on said platform means when the platform means shift horizontally due to a reduction in the axial length of the beam due to its deflection to thereby prevent such horizontal or angular force components from affecting the sensing by said integral strain gage transducer beam means while simultaneously transmitting said vertical force components.

2. The apparatus of claim 1, wherein said cup of said first curved surface means faces upwardly with its depression, wherein said ball reaches downwardly into said depression, said apparatus further comprising a flexible element which retains said ball while permitting horizontal movement of said ball in said curved cavity which is larger in its curvature than the curvature of said ball, said flexible element simultaneously damping horizontal movements of said platform means relative to each other.

4. The apparatus of claim 1, wherein said first curved surface means comprise two cups each having a depression therein, one depression facing downwardly the other depression facing upwardly, said apparatus further comprising a flexible element comprising a length of flexible elastomeric tubing encircling said two cups to hold said ball between the two cups in said depressions, said flexible element simultaneously damping horizontal movements of said platform means relative to each other.

5. The apparatus of claim 1, further comprising movement limiting means (14, 16) operatively secured to one of said platform means and cooperating with the other platform means for limiting a horizontal movement of one platform means relative to the other platform means and means (17) connected to said movement limiting means for preventing the vertical separation of said platform means from each other.

6. The apparatus of claim 1, further comprising a flexible sleeve operatively secured at one end to the upper horizontal platform, said cup being secured to the lower horizontal platform, said flexible sleeve encircling with its other end said cup, thereby providing a flexible, restoring and damping coupling between said platforms.

3. The apparatus of claim 3, further comprising means securing said flexible element in the form of a piece of elastomeric tubing to face downwardly and to encircle said cup.

7. An apparatus for transmitting vertical force components between an upper horizontal member and a lower horizontal member, said members extending substantially in parallel to each other, comprising bracket means rigidly connected to the upper horizontal member, said bracket means being constructed to extend from the upper horizontal member to a position below the lower horizontal member without contacting said lower horizontal member under normal operating conditions, and suspension means extending between the lower horizontal member and the portion of the upper horizontal member bracket means extending below the lower horizontal member for suspension of the upper horizontal member from the lower horizontal member, said suspension means affording a substantially unyielding coupling between the upper and lower horizontal members in the vertical direction for transmitting vertical force components from the upper horizontal member to the lower horizontal member, said suspension means affording substantially yielding and flexible coupling between the upper and lower horizontal members in the horizontal direction, thereby substantially preventing transmission of horizontal force components between the upper and lower horizontal members, and foot means (43) connected to the lower horizontal member for supporting said apparatus to provide sufficient clearance for said bracket means (48), wherein each of said suspension means comprises a suspension cable and a bearing ball, said suspension cable being connected at its upper end to said bearing ball and wherein said lower horizontal member is formed with curved surface socket means in which said bearing ball rests.

8. An apparatus for applying a load to a strain gage transducer beam in a platform scale, comprising first lower platform means (1) having feet (2) for spacing the lower platform means above a floor, strain gage transducer beam means forming integral components of said first lower platform means, second upper platform means (3) arranged above and substantially in parallel to said first lower platform means (1), load transmitting means for transmitting vertical load components to said integral strain gage transducer beam means from said second, upper platform means (13) while simultaneously substantially preventing the transmission of horizontal or angular load components to said integral strain gage transducer beam means, said load transmitting means comprising for each integral strain gage transducer beam means a hardened steel ball (24) having a given radius, two hardened steel cups (22) with a depression (23) having a radius of curvatures larger than said given radius of the hardened steel ball for holding said steel ball in said depressions (23) of the cups, a flexible rubber tubular member surrounding said steel ball and rigidly connected at one end thereof to one of said platform means and operatively connected with the other end thereof to the other platform means for effectively damping vibrations of the platform means relative to each other caused by horizontal or angular load components, said apparatus further comprising holes (16) of a given diameter in said lower platform means (1), and shoulder bolts (14) rigidly connected at the upper end thereof to said upper platform means and having a diameter smaller than said given hole diameter, each shoulder bolt extending through its respective hole (16) for stopping horizontally or angularly effective shocks exceeding the damping capability of said flexible rubber tubular member (25), each shoulder bolt further having at its lower free end below said first platform means a member (17) of larger size than said hole diameter for preventing the separation of said upper and lower platform means from each other in the upward vertical direction, and wherein said steel ball (24) by virtue of its substantially frictionless rolling in said depressions (23) compensates for small horizontal shifts of said cups relative to each other resulting from a shortening of the axial length of the respective transducer beam means when the latter deflects, to thereby prevent undesirable horizontal and angular force components from becoming effective on the transducer beam means.