GB2157008A

GB2157008A - Weighting machines

Info

Publication number: GB2157008A
Application number: GB08409056A
Authority: GB
Inventors: Wang Felipem
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-04-07
Filing date: 1984-04-07
Publication date: 1985-10-16
Also published as: GB8409056D0

Abstract

A weighing machine includes a movable frame 52 which is held and controlled by a spring assembly 55 and is movable in response to the weight of an object. The frame 52 is guided by two upstanding members 51 which are placed adjacent thereto and in rolling contact with balls 53. <IMAGE>

Description

SPECIFICATION Improvements relating to weighing machine This invention relates to weighing machines, particularly to a weighing machine of improved construction that offer more accurate weighing results and increased durability.

There is a typical spring scale 10 which includes a housing 11 and a scale disc 12, as shown in Figure 1. Inside the housing is mounted a vertical movable frame 13, a portion of which is projected outwardly of the housing 11 for supporting a balance pan 14, the frame 13 being hung at an elevated position from the base of the housing 11 by spiral springs 15 which have their one ends mounted at the top sides of the housing 11. Arms 162 and 163 which are pivoted to the fixed bar 161, and pivoted arm 164 are movably connected to the frame 13 for guiding the frame 13 to move vertically in upward and downward directions. The movable frame 13 is further connected to a transmitting unit 17 which transmits the movement of the frame 13 to the pointer of the scale for showing the reading of the weighed object.

The movable frame 13 in the spring scale not only supports the balance pan 14 but also the object to be weighed, and its movement caused by the weight of the object is transmitted to the pointer of the scale. It is found that the way in which the frame is guided through the pivoted arms 162, 163 and 164 is deficient. The frame 13 does not move in an actual vertical upward and downward direction, resulting in errors in the resultant magnitude of the deflection of the spring as well as inaccuracy in the readings of the weight. In addition, as the arms 162, 163 and 164 are pivoted to the frame 13, the movement of the frame 13 might be subjected to the restriction from the arms, and this also affects the sensitivity of the spring as well as the resultant readings of the weights. Furthermore, the incorporation of the arm assembly into the frame is rather complicated and is not durable.

An object of the invention is to provide a spring scale of durable and simplified construction that can offer a long time service.

Another object of the invention is to provide a spring scale of improved construction that can minimize errors created in the resultant magnitude of the deflection of the spring.

The foregoing and other objects can be achieved in accordance with the invention through the provision of a weighing machine having a vertically movable frame which is connected to an object pan and responsive to the weight of the object, and characterized by two upstanding members respectively located adjacent to two sides of the frame for guiding the frame to move in a proper direction, and rolling members provided between the adjacent surfaces of the frame and the upstanding member minimizing the frictional contact.

Advantageously, the weighing machine may be a spring scale which includes a vertically movable frame connected to an object pan and is held by a spring assembly, the frame being guided by two upstanding members which are respectively placed adjacent to the sides of the frame and are kept in a minimum frictional contact relationship with the frame, thereby improving the sensitivity and the accuracy of the spring scale.

The presently preferred exemplary embodiment will be described in detail with reference to the following drawings, wherein: Figure 1 is a spring scale in the prior art; Figure 2 is a first embodiment of the spring scale in accordance with the present invention; Figure 3 illustrates the relation between an upstanding guide member and a vertical member of the movable frame; Figure 4 is a second embodiment of the spring scale; Figure 5 is a third embodiment of the spring scale; and Figure 6 is a fourth embodiment of the spring scale.

Referring to Figure 2, there is shown a first embodiment in which a spring scale 20 includes a housing 21, a scale disc 22 and an object pan 24.

Two upstanding flat members 231 are projected from the base 23 inside the housing 21. A frame 232 is placed between the upstanding members 231 and is hung at an elevated position by helical springs 25. The helical springs 25 have their top ends mounted to the top side of the housing 21 by a known manner as done in the conventional spring scale. The bottom sides of the springs is connected to the bottom side of the frame 232, thereby suspending the frame 232 at a certain height above the base 23.

The frame 232 is a rectangular member which includes parallelly spaced apart vertical flat members 232a interconnected by two horizontal flat members. Two vertical members 232a are respectively provided with longitudinal grooves 2321 of hemispherical shapes in their cross-sections at their outer sides. At the opposing faces of the upstanding members 231 which are adjacent to the grooved sides of the vertical members 232a are provided longitudinal grooves 2311 of hemispherical shapes in their cross-sections, the grooves 2311 being in registration with the grooves 2321 respectively.

Clearances are provided between the upstanding members 231 and the vertical members 232a of the frame 232. In the tubular channels defined by the grooves 2321 and 2311 are located balls 233 as better seen in Figure 3, and the peripheries of the balls are in contact with the grooved surfaces of the upstanding members 231 and the vertical members 232a. When the frame 232 is moved in response to the weight of the object, the balls will roll and move along with the frame 232. Near the top ends of the grooves 2311 are provided screws 2312 of which ends are projected into the grooves 2311 for preventing the escape of the balls 233 from the channels. At the bottom ends of the grooves 2321 are also provided screws 2322 of which ends are projected into the grooves 2321 for retaining the balls 233 from falling out of the chan nels.As can be appreciated in Figure 3, the frame 232 is guided by the upstanding members 231 which is in rolling contact therewith, thereby minimizing the friction between the frame 232 and the upstanding members 231 or the restriction of the upstanding members 231 which will influence the magnitude of the deflection of the springs 25.

There are further provided screw holes 241 at the top side of the frame 232 for attachment of the object pan 24. As the top side of the frame 232 is a broad flat member, the pan 24 which is supported by that frame 232 is more stable than the pan which is supported by the conventional movable frame made of a narrow bar.

There is further provided a transmitting unit which includes an arm 27 one end of which is fixed to the wall of the housing 21. It is connected to the bottom side of the frame 232 through a linkage 271 and is further connected to a gearing mechanism (not shown) which transmits the movement of the arm 27 to a pointer of the scale 22 for showing the reading of the weight. As the constructions of the transmitting assembly and the scale is known by anyone who skills in the art, the details thereof are not herein described.

It can be appreciated that the movement of the frame 232 caused during weighing the object is an actual vertical upward and downward direction due to the guidance of the upstanding members 231.

Accordingly, more accurate magnitude of the deflection of the spring will be transmitted to the scale. Furthermore, the upstanding members 231 are more simple and durable than the pivoted arms which are used in the conventional spring scales.

Referring to Figure 4, there is shown a second embodiment in which the spring scale 30 includes a housing 31, a scale 32, and an object pan 34. Inside the housing 31 is provided two upstanding members 331 of arc-shaped cross-sections. A cylindrical frame 332 which has an open top and a closed bottom is located between the members 331. There are further provided brackets 3322 and 3323 mounted to the open top of the frame 332 and projected outwardly of the housing 31 for attachment of the object pan 34. Four springs 35 are suspended at the top side of the housing 31 by attachment means 311. The bottom ends of the spring 35 are connected to the closed bottom of the frame 332, thereby hanging the frame 332 at a certain elevated position.

On the upstanding members 331 and the vertical periphery of the frame 332 are provided grooves 3311 and 3321 respectively, and the channels defined by the grooves 3321 and 3311 are provided with balls 333, screws 3312 and 3324, as shown in Figure 3, like the first embodiment. There are further provided a transmitting unit which transmits the deflection of the springs 35 to the scale 32, an arm 37 of the transmitting unit being connected to the frame 332. The spring scale 30 also offers the advantages similar to that of the first embodiment.

Referring to Figure 5, there is shown a third embodiment in which an improvement in accordance with the invention is made to a spring scale 40 which includes a circular scale 42, a housing (not shown) accommodating a spring assembly and a transmitting unit, and a hanger 44 provided at the bottom side of the housing for hanging an object.

The improvement comprises two upstanding mem bers 411 which guide a frame 412 which has two vertical sides adjacent to members 411 and a transverse bottom side to which is attached an attachment rod 43 for hanger 44. Rolling balls 413 are provided between members 411 and the frame 412 in the same manner as the previous embodi ments for friction reduction. The spring assembly is fixed at the top side of the housing and con nected to the bottom side of frame 412. By means of this improvement, the movement of the spring assembly can be properly guided and the scale will provide accurate readings.

Referring to Figure 6, there is shown a fourth embodiment in which a spring scale 50 includes a pan 54 which is supported by a compression spring 55. At the bottom side of pan 54 is attached two vertical flat members 52 and between them are provided two upstanding members 51. These upstanding members 51 guide the movement of the vertical members 52 through rolling balls 53 in the same manner as described in the previous embodiments. At one of the upstanding members 51 are provided a scale 511 in which the deflection of the spring 55 is converted into a direct reading of weight. The lowermost point 521 of the vertical member 52 is used as an indicator for showing the weight of the object. The spring scale 50 is of very simple construction and capable of providing an accurate reading of weight.

With the invention thus explained, it is apparent that obvious modifications and variations can be made without departing from the scope of the in invention It is therefore intended that the invention be limited only as indicated in the appended

Claims

claims. CLAIMS

1. A weighing machine including a vertically movable frame which is connected to an object pan and responsive to the weight of the object, characterized by two upstanding members respectively located adjacent to two sides of the frame for guiding the frame to move in a proper direction and rolling members provided between the adjacent surfaces of the frame and the upstanding members for minimizing the friction between the frame and the upstanding members.

2. A spring scale including a vertically movable frame which is held by a spring assembly and is connected to an object pan for responding to the weight of the object, characterized by two upstanding members respectively located adjacent to two sides of the frame for guiding the frame to move in a proper direction, and rolling members provided between the adjacent surfaces of the frame and the upstanding members for minimizing the friction between the frame and the upstanding members.

3. A spring scale comprising an object pan, two downwardly projecting flat face members at the bottom side of the pan, a compression spring member provided between the two flat face projecting members and normally biassing the pan upward, two upstanding flat face members provided on a base and respectively adjacent to the downwardly projecting members for guiding the movement of the pan, and rolling means provided between the adjacent surfaces of the downwardly projecting members and upstanding members for minimum frictional contact.

4. A spring scale including a vertically movable frame having at its bottom side an attachment means for the object members and suspended by a spring assembly characterized by two upstanding members respectively provided adjacent to two sides of the frame for guiding the movement of the frame, and rolling members provided between the adjacent surfaces of the frame and the upstanding members for minimum frictional contact.

5. A weighing machine comprising means for receiving an object to be weighed; a substantially vertically movable support means which is coupled to said receiving means for supporting said receiving means and is movable in response to the weight of the object; guide means for guiding the support means to move in a proper direction and means provided between adjacent surfaces of the support means and the guide means for minimizing the friction therebetween.

6. A spring scale substantially as hereinbefore described with reference to the accompanying drawings.