Apparatus for measuring the thickness of flower stems

Abstract: This invention relates to an apparatus for grading flowers on the basis of the thickness of the stem, wherein each flower stem is passed between a rotatable roller (6) and a restraint (7). One of these two members is arranged for movement and is urged towards the other member under the influence of a force. The displacement of the rotatable roller resulting from the passage of the flower stem is a measure for the thickness of the stem. The rotatable roller is driven at a peripheral velocity which is approximately equal to the speed of the passing flowers.

Description: The invention relates to an apparatus for grading the stem thickness of a flower comprising an endless conveyor having a plurality of forks for receiving and supporting a vertically disposed single flower. An apparatus of this type is disclosed in EP-A-0,449,386, which constitutes a prior art reference in the sense of Art. 54(3) EPC, said apparatus being adapted to determine the length of the stem of a flower, which length is an important quality factor. US-A-2,885,787 discloses a method of measuring thickness in an apparatus for grading objects such as boards and the like on the basis of thickness. In this known apparatus, each board can be passed between a rotatable roller and a restraint. One of these two members is arranged for movement and is urged towards the other member under the influence of a force. The displacement of the rotatable roller resulting from the passage of the board is a measure for the thickness of the board. The invention has for its object to provide an apparatus adapted to measure another important quality factor, being the thickness of the stem, said thickness being dependent on the amount of sun that the plant has received during its growing period. According to the invention this object is achieved by an apparatus which further comprises a rotable restraining roller, adapted to rotate about a fixed vertical shaft a rotatable and displaceable roller, also adapted to rotate about a vertical shaft and supported by a displaceable end of a lever such that the periphery of the displaceable roller is urged towards the periphery of the restraining roller by a spring means and the restraining roller and displaceable roller are positioned relative to the forks such that the stem of each flower in each fork passes between said rollers drive means for rotating the displaceable roller at a peripheral velocity which is approximately equal to the speed of the conveyor and measuring means for measuring the displacement of the displaceable roller caused by the passing of a flower stem between the said rollers whereby the thickness of a flower stem is determined. With the apparatus according to the invention the speed difference between the rollers and the vulnerable stems to be measured can be eliminated, preferably by driving both rollers at peripheral velocity which is approximately equal to the travelling speed of the conveyor and/or by coating one of said rollers with a material having a relatively high coefficient of friction. The measurement of the displacement of the lever, and hence of the thickness of the stem is preferably effected by means of a proximity switch - an induction sensor, generating an output signal that is dependent on the displacement of the lever relative to its zero position. Instead of an induction sensor an encoder arranged adjacent the pivot point of the lever can be used to measure the displacement referred to. By arranging a plurality of such apparatuses for measuring the stem thickness above each other at intervals that correspond with the desired grading length ranges, it is also possible to use the present measuring apparatus for measuring the length of the flowers to be graded. By relating to each other the times at which each stem passes the different measuring systems arranged above each other, it is also possible to determine the straightness of a stem, which is another important factor in determining the quality of a flower. Embodiments of the apparatus for measuring the thickness of a stem will now be described, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic top plan view of an apparatus for measuring the thickness of the stem of a flower; Fig. 2 is a side elevation of the apparatus of Fig. 1; Fig. 3 is a view similar to Fig. 1 of a second embodiment of an apparatus for measuring the thickness of a stem; Fig. 4 is a view similar to Fig. 2 of the apparatus of Fig. 3; and Fig. 5 is a view similar to Figs 2 and 4 of a third embodiment according to the invention. Referring to the drawings, there is shown an apparatus for measuring the thickness of the stem of a flower 1, comprising forks 2 which are part of a diagrammatically shown endless conveyor 3, as is disclosed in EP-A-0.449.386, referred to above. Arranged adjacent the guideways 4 and 5 for the flower stems 1 conveyed by the conveyor 3 is a fixed roller 6 mounted for rotation about a shaft 8. Arranged diametrically opposite roller 6 is a roller 7 mounted for rotation about a shaft 9. Rollers 6 and 7 are both coated with a material, not further specified, having a relatively high coefficient of friction, to ensure that the flowers are not damaged, i.e. , no slip should occur between the flower stem 1 and either of the rollers 6,7. Mounted on shaft 9 is a chain wheel 10 which is driven via a chain 11 by a chain wheel mounted on shaft 12 between bearing blocks 13, rigidly secured to a frame 14. The shafts 9 and 12 are further interconnected by means of a lever 15 which is rigidly connected to a lever 16. The lever 16, which extends substantially parallel to the corresponding portion of the frame 14, cooperates with a buffer 17 which is arranged for absorbing shocks during the displacement of the movable roller 7 relative to the fixed rotatable roller 6. Arranged adjacent the buffer 17 is an induction sensor 18 in the form of, for instance, a proximity switch generating an analog output signal. Arranged adjacent sensor 18 is an adjustment bolt 19 for adjusting the zero position of the measuring apparatus. Arranged adjacent the bolt 19 is a tension spring 20 which is arranged for pulling the lever 16 back into the zero position and is extended each time a flower stem passes between the rollers 6 and 7. As the apparatus shown in Figs 3 and 4 largely corresponds to that shown in Figs 1 and 2, it will not be described in detail here, but only the modifications to the apparatus of Fig. 1 will be described. These modifications concern the drive of the roller 7, which is effected by means of a servomotor 21 mounted on the shaft 9. The displacement of the roller is measured by means of an encoder 22. This embodiment, therefore, does not comprise a proximity switch 18 as used in the embodiment according to Fig. 1, but otherwise the apparatuses are similar. The embodiment shown in Fig. 5 differs from the embodiment shown in Figs 2 and 4 in that the rollers 6 and 7 have been replaced by respective pairs of similar rollers 26 and 27 arranged above each other. In this manner, it is ensured that the flowers that are being supplied continue to be suspended in a straight orientation when the stem passes between the rollers. The respective rollers 26 and 27 may be interconnected by means of a hub and mounted on a single shaft in the same manner as in the embodiment of Figs 2 and 4. The shaft on which the rollers 27 are mounted can be driven by a single servomotor in the same manner as in the embodiment of Fig. 4.

Claims: Apparatus for grading the stem thickness of a flower comprising an endless conveyor (3) having a plurality of forks (2) for receiving and supporting a vertically disposed single flower (1), characterized in that the apparatus further comprises a rotable restraining roller (6, 26), adapted to rotate about a fixed vertical shaft (8) a rotatable and displaceable roller (7, 27), also adapted to rotate about a vertical shaft (9) and supported by a displaceable end of a lever (15) such that the periphery of the displaceable roller (7, 27) is urged towards the periphery of the restraining roller (6, 26) by a spring means (20) and the restraining roller (6, 26) and displaceable roller (7, 27) are positioned relative to the forks (2) such that the stem of each flower (1) in each fork (2) passes between said rollers (6, 26), (7, 27) drive means (10, 11) for rotating the displaceable roller (7, 27) at a peripheral velocity which is approximately equal to the speed of the conveyor (3) and measuring means (18) for measuring the displacement of the displaceable roller (7, 27) caused by the passing of a flower stem (1) between the said rollers (6, 26), (7, 27) whereby the thickness of a flower stem (1) is determined. Apparatus according to claim 1, characterized in that both rollers (6, 26), (7, 27) are driven at said velocity. Apparatus according to one or more of the preceding claims, characterized in that the displacement is measured by means of an induction sensor (18) generating an output signal that is dependent on the displacement of the lever (15, 16) relative to its zero position and is a measure for the thickness of the stem (1). Apparatus according to one or more of claims 1-2, characterized in that the displacement is measured by means of an encoder (22) arranged adjacent the pivot point of the lever (15, 16). Apparatus according to one or more of the preceding claims, characterized in that at least one of said rollers (6, 26), (7, 27) is coated with material having a relatively high coefficient of friction. Apparatus according to claim 1, characterized in that a plurality of sets of said rollers (6, 26), (7, 27) are arranged above one another with the rollers (6, 26), (7, 27) of one set being vertically disposed above the rollers (6, 26), (7, 27) of another set for measuring the length of the flowers to be graded. Apparatus according to claim 6, characterized in that the straightness of a stem can be determined by relating to each other the times at which the stem passes the different sets of rollers (6, 26), (7, 27) arranged above each other. Apparatus according to one or more of the preceding claims, characterized in that the rollers (6, 26), (7, 27) each comprise a double disc.

Inventors: TAS ADRIANUS WILHELMUS, TAS, ADRIANUS WILHELMUS
Applicants: AWETA BV, AWETA B.V.
Application year: 1992
Main classification: A01G5
IPC codes: A01G5, B07C5