Apparatus for measuring the flexural resistance of ribbed patterns

Abstract: An apparatus for measuring the flexural resistance of ribbed patterns comprises a clamp (1) for clamping a die-cut and ribbed cardboard sheet (2), which clamp is so driven as to cause the ribbed portions of the cardboard sheet to engage against one or more rollers (4) which are coupled to corresponding load cells (5) adapted to measure the force necessary for folding the ribbed portions and display this force on a display.

Description: BACKGROUND OF THE INVENTION The present invention relates to an apparatus for measuring instantaneously the flexural resistance of ribbed patterns or elements, in particular cardboard ribbed elements. As is known for packaging purposes there are frequently used cardboard sheets which are provided with ribbed patterns on their surface and are die-cut so as to provide a box-like configuration adapted to hold a lot of different products. At present there are not known means for instantaneously measuring, in a reliable way, the proper characteristics of ribbed cardboard sheets to be used for packaging goods, in industrial packaging operations. Known flexural resistance measuring devices, in fact, are mainly of the laboratory type, and are very complex and expensive. Patent Abstracts of Japan, vol.11 No. 345 (P-636) |2972| 12th November 1987; and JP-A-62 127 643 (DAINIPPON PRINTING CO.,LTD.) 09.06.1987 (which are considered the most pertinent prior art) disclose an apparatus comprising a clamp member for clamping the cardboard sheet to be tested, and an element which is rotated about an axis which coincides substantially with the axis therealong there extends the ribbed pattern on the cardboard sheet clamped in the clamp element. This turning element, which actually forms the member which is provided for deforming the sheet along the ribbed pattern, comprises a plate which bea s by a surface thereof against a face of the sheet the bending resistance of which must be measured. The rotary plate is connected through a resilient element, for example a thread or yarn, to an apparatus which measures the tension applied to the yarn and accordingly derives directly therefrom the force necessary to generate the be nding of the sheet along the ribbed pattern. SUMMARY OF THE INVENTION Thus, the main object of the present invention is to overcome the above mentioned drawbacks, by providing an apparatus which able of measuring the flexural resistance of ribbed cardboard sheet material, in particular for packaging purposes, in a very short time. Another object of the present invention is to provide such a flexural resistance measuring apparatus which is very simple to use. Another object of the present invention is to provide such a flexural measuring apparatus which is very reliable in operation and can be used directly on the cardboard sheet making line. According to one aspect of the present invention, the above mentioned objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by an apparatus for instantaneously measuring flexural resistance of ribbed cardboard sheet material, having the features of the characterizing part of the main claim. BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the apparatus according to the present invention will become more apparent from the following detailed disclosure of a preferred embodiment thereof, which is illustrated, in the figures of the accompanying drawings, where: FIGURE 1 is an elevation schematic view of the apparatus according to the invention; FIGURE 2 is a side perspective view of the apparatus according to the invention; and FIGURES 3 and 4 illustrate the operating mode of the apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the figures of the accompanying drawings, the apparatus for instantaneously measuring the flexural resistance of ribbed patterns, in particular on cardboard sheet material, according to the invention, comprises essentially a clamp assembly indicated generally at the reference number 1 and comprising a pair of flat plates which can be mutually clamped in any suitable manner, for example by means of actuators driven by suitable sensors (not shown). The plates are provided for clamping therebetween a cardboard sheet 2, provided for forming, upon folding, a desired packaging box or the like. As is shown, the mentioned pair of plates can slide between the uprights 3 of a frame, said plates being horizontally reciprocated by driving means. These driving means can comprise any suitable driving arrangement. According to a possible embodiment, for example, the clamp assembly 1 can be mounted on small columns or rods rigid with suitable guides and provided with a rack shaped bottom portion therewith a pignon engages, which is driven by a geared motor unit (not shown). In operation, the clamp assembly 1 is upwardly driven so as to cause the ribbed portion 2' of the cardboard sheet to engage with one or more rollers 4 which are suitably coupled to respective load cells 5, arranged above the clamp assembly 1 and having a longitudinal axis substantially parallel to the sheet 2 when held by the clamp assembly. As is known, the flexural resistance of a ribbed portion or pattern 6 to a bending stress, comprising a 90° folding of the ribbed portion so as to form the packaging box, increases as the bending angle increases and reaches a maximum value for a bending angle of 90°. Thus, according to the invention, the clamp assembly and roller are so arranged that the portion 2' of the cardboard will be deflected according to a right angle bend before the clamp assembly going beyond the roller (see fig.4). The flexural resistance of the mentioned portion 2' will be sensed by the above mentioned load cell, the output signal of which,after suitable amplification and conversion, will drive any suitable display means. In this connection it should be pointed out that a repeated measurement on the same fold will provide progressively decreasing read-outs. Thus, by storing the subsequent flexural resistance values in a pre-programmed computer store, and using a roller which can be displaced by set distances along its axis, it will be possible to evaluate the flexural resistance of two or more adjoining ribbed portions. In particular, the roller must be counterbiassed, for example by means of a radial arm 7, in order to cancel the weight of said roller(which, on the other hand can also be electronically cleared by a suitable calibrating procedure. Moreover the roller must be mounted on bearings in order to prevent the measurement read-outs to be negatively affected by a possible unevenness of the ribbed portion surface. It is to be moreover pointed out that: the roller will be coupled to the load cell preferably by means of a rigid type of coupling, in order to hold said roller at a fixed position; the position of the roller with respect to the clamp assembly, and accordingly to the fold, must not be affected by the thickness of the cardboard sheet.

Claims: An apparatus for instantaneously measuring a flexural resistance characteristic of a ribbed cardboard sheet (2) to be used for making, upon folding, a packaging article, said apparatus comprising a clamp assembly (1) for supporting and firmly clamping said ribbed cardboard sheet (2), characterised in that said apparatus comprises driving means for upwardly and downwardly driving said clamp assembly (1) and said ribbed cardboard sheet (2) so as to urge a ribbed portion (2') of said sheet (2) against at least a roller (4) being above said clamp assembly and having a longitudinal axis substantially .parallel to said sheet (2) when held by said clamp assembly, at least a roller (4) being so arranged that, when said ribbed portion (2') is urged against said at least a roller (4), said ribbed portion (2') being bent by said at least a roller (4) through substantially 90°, said at least a roller (4) being operatively coupled to a load cell means (5) for sensing a bending force exerted by said at least a roller (4) in bending said ribbed portion (2'), said load cell means (5) being coupled to bending force display means for displaying said bending force thereon. An apparatus according to Claim 1, characterized in that said clamp assembly (1) comprises a pair of reciprocating flat plates which can be clamped against one another by actuating means driven by sensor means. An apparatus according to Claim 2, characterized in that said plates are slidably mounted between uprights members (3) of a frame of said apparatus. An apparatus according to Claim 1, characterized in that said at least a roller (4) can translate along said longitudinal axis thereof. An apparatus according to Claim 1, characterized in that said at least a roller (4) is counterbiassed by a radial arm member (7). An apparatus according to Claim 1, characterized in that said at least a roller (4) is mounted on bearing means. An apparatus according to Claim 1, characterized in that said at least a roller (4) is rigidly coupled to said load cell (5).

Inventors: CRESPI GIUSEPPE, CRESPI, GIUSEPPE
Applicants: CRESPI CARTOTECNICA, CARTOTECNICA CRESPI S.P.A.
Application year: 1990
Main classification: G01N3
IPC codes: G01N3