Automatic spew trimming method and apparatus used therefor

Abstract: An automatic spew trimming method wherein a tyre is rotated supported from inside to be trimmed by a knife and an apparatus used therefor. The apparatus comprises a supply conveyor (1), a tyre rotating section (3), a cutter (10) for tyre tread, a cutter (11) for a sidewall, and a discharge conveyor (32). According to the method and the apparatus of the present invention, even a tyre such as a motorcycle tyre having low rigidity, small tread width and nearly completely round cross section can be trimmed to cut off spew. Further, even if many kinds of tyres of different sizes are supplied at random, they can be satisfactorily accommodated and treated.

Description: The present invention relates to an automatic spew trimming method and an apparatus therefor wherein spew or flash generated in the vulcanising step can be cut off from the external surfaces of various kinds of vulcanised tyres. Trimming of a vulcanised tyre has been conventionally carried out by independently rotating the tyre on two drive rollers and two guide rollers for trimming by a knife. The rollers are positioned to contact the outer circumference of the tyre. Another conventional trimming method is carried out by assembling a tyre to a rim and inflating it, then the tyre is rotated by rotating the rim and the tyre is trimmed with a knife. However, the above-mentioned two conventional trimming methods both have respective drawbacks. In the method where a tyre is independently rotated and trimmed by a knife, trimming of a low rigidity tyre and particularly of a tyre of a small tread width such as a motor cycle tyre is impossible because smooth rotation of such tyres is impossible on rollers. In this method, even if the apparatus is adjusted or modified, that is the roller pressure is changed or the roller shape is specially determined for the tyre concerned, to enable the trimming of the tyre, the apparatus is then limited to exclusive use for the particular tyre so that other kinds of tyre cannot be trimmed. In the method where the tyre is assembled onto a rim for rotation the rim must be changed to match the rim diameter for tyres of different rim diameter. Thus flexible operation cannot be realised. A method and apparatus for removing the tread rubber portion of a tyre prior to retreading, wherein the tyre is supported from inside and rotated against a cutter contacting the tread, are known from US-A-1668214. However in this method the cutter is fixed in one position relative to the tread which limits the usefulness of the apparatus. It is an object of the present invention to overcome these disadvantages to allow trimming of many kinds of tyres of different rigidity, tyre tread width and size on a single machine. According to one aspect of the present invention an automatic spew trimming method is provided in which the tyre is rotated about its axis, supported from inside and trimmed by a knife characterised by the steps of measuring the outer diameter of the tyre, measuring the width of the tyre, controlling a position to which the tyre is lifted along its rotational axis, based on the measured tyre width, determining a rotation centre for a cutter for the tyre tread, based on the measured outer diameter of the tyre, the axis of rotation of the cutter being perpendicular to a plane containing the tyre rotation axis, determining the amount of rotation for the cutter for the tyre tread, based on the measured tyre width and trimming the tyre tread with the cutter based on the determined rotation centre and on the determined amount of rotation. Another aspect of the invention provides an apparatus for automatically trimming spew comprising a supply conveyor which may supply a tyre to a trimming section, including tyre rotation means having a tyre holding mechanism and being positioned at downstream of the supply conveyor, the holding mechanism comprises a chuck to support the tyre from the inside of the tyre, a cutter for trimming the tyre tread provided at the tyre rotating section, and a discharge conveyor continuing from the supply conveyor characterised by a cutter for a tyre sidewall also provided at the tyre rotating section, a tyre measuring unit or section for measuring the inner diameter, the outer diameter and the width of the tyre, means for controlling by these measurements the operational positions of the cutters, the measuring section being positioned in the vicinity of the supply conveyor, a controlling means for memorising the data measured by the measuring section and controlling the movements of the cutters, means for moving the tread cutter into contact with the tyre tread and means for rotating the tread cutter by a rotational amount around a rotational centre both determined from the measurements of the inner tyre diameter, the outer tyre diameter and the tyre width, whereby the cutter rotating axis is perpendicular to a plane containing the rotational axis of the tyre, and means for moving the sidewall cutter into contact with the tyre sidewall and along the sidewall from a trimming start position to a trimming finish position. In the method and apparatuses of the present invention, the tyre is supported from inside, so that spew of the tyre can be trimmed even for tyres such as a motorcycle tyre having low rigidity, small tread width and a nearly completely round cross section. Further, trimming can be carried out without parts replacement on the machine even for tyres of different bead diameters. Moreover, even if many kinds of tyres are supplied to the apparatus at random, the apparatus can satisfactorily accommodate them because information about a tyre such as the outer diameter, the inner diameter, the tyre width, the spew cut area, the number of spew and the like are previously inputted to the machine and in fact measured and subsequently used by the machine itself and the cutters are moved according to the input information. Embodiments will now be described, by way of example only, in conjunction with the attached diagrammatic drawings in which: Figures 1, 2 and 3 are respectively a block diagram of the trimming method of the present invention; Figure 4 is an explanatory view explaining the inner diameter, outer diameter and the like of the tyre; Figure 5 is a schematic side view of the apparatus of the present invention; Figure 6 is a schematic front view of the apparatus in Figure 5; Figure 7 is a schematic plan view of the apparatus in Figure 5; Figure 8 is a schematic explanatory view of a measuring section of the apparatus of Figure 5; Figures 9 and 10 are respectively an explanatory view of the expanded and contracted positions of a mounting or chuck of the apparatus of Figure 5; and Figure 11 is an explanatory view of the cutters. Firstly the method is as follows. The inner or bead diameter a, outer diameter b and width c of a tyre are as shown in Figure 4. Further, a position d at which sidewall trimming is to be finished, a position e from which sidewall trimming is to be started and the rotational movement or fluctuation amount g for the cutter 10 for trimming a tyre tread are also shown in Figure 4. In Figure 4 h represents the equatorial line of a tyre. A cutter 10 for cleaning the tyre tread moves in the directions indicated by arrows B, C, D and E in this order covering the whole area of the fluctuation amount g. The cutter 10 is moved by a bow-shaped member 14 (see Figure 11) and is also pressed in the direction A by a cylinder 16 (see Figure 11). Firstly, the cutter 10 trims the tyre while moving in the direction B from a position on the equatorial line, and then is quickly returned (in a direction C) to the original position. Secondly, the cutter 10 trims the tyre by moving in the direction D, and then quickly returns (in the direction E) to the original position. On the other hand, a second cutter 11 for the sidewall trims the tyre moving from the trimming start position e to a trimming finish position d. the cutter 11 is moved from the position e to the position d by a supporting bar 18 (see Figure 11) while being pressed in the direction F by a cylinder 19 (see Figure 11). The sidewall trimming start position e is determined by subtracting an amount (Delta)b1 from the measured outer diameter b of the tyre. The amount (Delta)b1 is previously selected for a certain specific outer tyre diameter. A rotational centre f is determined by subtracting an amount (Delta)b2 from the measured outer diameter b of the tyre. The amount (Delta)b2 is previously selected for a certain specific outer diameter. Further, rotational movement or fluctuation amount g of the cutter 10 is determined by subtracting a correction amount (Delta)g from the measured tyre width c and calculating a rotation angle α from the equatorial line h. The correction amount (Delta)g is previously selected according to the specific tyre width the above-mentioned selected amount (Delta)b, and correction amount (Delta)g which vary depending on the tyre size which is previously inputted to a computer from which input for the control means for the trimming apparatus is controlled. An apparatus for the present invention will now be described in which a conveyor 1 extends to a point above a tyre measuring unit 20. Four measuring bars 21 to measure the tyre inner diameter move upwards from just below the tyre to be inside the tyre. Then, these four bars 21 move horizontally in synchronised radially outward directions in two straight lines at right angles to each other. that is, the bars 21 move outwards in four directions centring the tyre and measuring the inner diameter of the tyre simultaneously. The detailed structure of the measuring unit 20 is schematically shown in Figure 8. The operation of the bars 21 is controlled as follows. Four lateral shafts 23 are attached to a first sliding member 24. The shafts 23 extend in four radially outward directions in two straight lines crossing at right angles to each other. Four second sliding members 25 are slidably engaged with respective lateral shafts 23. The bar 21 is fixed to the second member 25. The first member 24, which is slidably engaged with a main shaft 22, is moved upward by an air cylinder (not shown). With the first member 24 moving upwards, the second members 25 and four measuring bars 21 move upwards. When one of the four second members 25 is moved along the lateral shaft 23 by an air cylinder (not shown), the other three second members 25 are also laterally moved in synchronisation because the four second members 25 are connected to the third sliding member 26 via links 27. The third member 26 is positioned below the first member 24 and slidably engaged with the main shaft 22. The main shaft 22 and the four lateral shafts 23 may be covered by bellows or the like so that ships or trimmings and the like are prevented from adhering to them. The inner diameter of the tyre is thus determined based on an amount of outward movement of the four bars 21. The width and an outer diameter of the tyre is determined as follows. When the determination of the inner diameter is finished, touch bars (not shown) are moved towards the sidewall and the tread respectively from above and the side. The touch bars are screw-operated by feed screws or the like to approach the tyre. When the bars contact the tyre at the sidewall or at the tread, they are stopped by a proximity switch. These stop positions are measured by encoders to calculate the tyre width and the outer diameter. In this embodiment the vertical and horizontal movements of the four bars 21 are realised by air cylinders. However, the bars can be moved by screws or the like instead of the cylinders. The data obtained by those measuring steps is inputted to the memory of a control means such as a sequence controller (not shown) and stored therein. Correction values for these data may be entered into a computer for minute adjustment. Thereafter the tyre is again carried by the conveyor to reach a trimming stage 3 and is again stopped. A chuck 60 of a tyre holding mechanism 5 is moved downwards by an air cylinder 4 and expands in diameter to support the tyre from inside. The chuck 60 expands its diameter so as to always outwardly engage the inside of the tyre in the vicinity of the tyre equator. For this reason, the tyre can be firmly supported and lifted up independently of its outer diameter and bead diameter. The upward movement of the chuck 60 is controlled based on the calculated tyre width so that the height of the centre line of the tyre width direction (the equatorial line in Figure 4) of the lifted up tyre is adjusted to be constant indedendently of the width of the tyre being handled. The mechanism to expand and contract the chuck 60 is shown in Figures 9 and 10 (Figure 9 is the view seen from below the chuck 60). The chuck 60 comprises a circular plate 62 fixed to a hollow main shaft 61 and a major gear 64 fixed to an inner shaft 63 penetrating through the hollow main shaft 61. Six minor gears 65 are pivotably supported by the circular plate 62. The minor gears are engaged with the major gear 64. When the inner shaft 63 is rotated by a rotary actuator 8 placed on a tyre rotating section 7, the major gear 64 and the minor gears 65 are also rotated. An arm 66 is fixed to each of the minor gears 65 so that rotation of the gear 65 causes the arm 66 to open or close. At the tip of the arm 66 a roller 67 is provided, whereby only a tyre which is supported by the rollers 67 which are pressed outwardly can be rotated by a drive roller 9. The drive roller 9 rotates contacting the tyre outside. The alternative proposal is for the chuck supporting the tyre and for a drive roller. The tyre is supported from inside by the chuck and the tyre is rotated by rotating the chuck. Another construction is where the tyre is supported at its bead for rotation. However, in the former, because the chuck and the tyre are rotated integrally and the tyre tread is forced by the chuck from inside, spew in the vicinity of the forced tread is more difficult to trim. In the latter because the tyre is supported at its bead, trimming in the vicinity of the supported bead is hard or impossible due to interference of cutter5s and the supporting members. In the above embodiment of the present invention, however, the tyre is supported from inside and is independently rotated by the drive roller 9 arranged outside the tyre during the trimming operation, whereby the above-mentioned drawbacks are overcome. Thus, according to the present invention, the trimming operation can be carried out well even for a tyre such as a motorcycle tyre having a small width, a nearly completely round cross section and low rigidity, which has not been automatically trimmable previously. When the tyre is lifted up, the drive roller 9 advances toward the tyre to contact it. The tyre is rotated by the rotation of the drive roller 9. The sequence controller (not shown) provides control means to operate a servo mechanism (not shown) so that the movements of the cutter 10 for the tyre tread and the cutter 11 for the sidewall are controlled based on the memorised data. Thus, the cutter 10 trims spew at the tyre tread and the cutter 11 trims spew at the sidewall. The control of the cutters 10 and 11 at this stage is carried out according to the block diagram shown in Figure 3. Next, the movements of the cutters 10 and 11 will be explained with reference to Figures 3, 4 and 11. The value measured of the tyre width in a step of measuring the width of they tyre shown in the diagram of Figure 3 is used to control the vertical movement of the chuck 60 so that the height of the centre line in a widthwise direction (the equatorial line in Figure 4) of the tyre in the trimming position is made constant independently of tyre width. A bow-shaped member 14, which is approximately arc-shaped, is moved by a servo motor (not shown) so that a shaft centre 13 corresponds to the fluctuation centre determined in the step of determining a fluctuation centre. A bell crank mechanism 15 is operated by an air cylinder 16, whereby the tread cutter 10 contacts the tyre tread. Simultaneously, the bow-shaped member 14 is moved by a servo motor 17 by the fluctuation amount g shown in Figure 4 to trim the tyre tread. A supporting bar 18 for the cutter 11 for the sidewall is moved by a servo motor (not shown) from a trimming start position (see Figure 3), to a trimming finish position, determined in the stop of determining a finish position (see Figure 3). In this movement (see Figure 4), a rack and pinion mechanism 31 is operated by an air cylinder 19 so that the cutter 11 contacts the sidewall to trim. As explained above, the cutters are moved in a specific range for spew cutting and on a specific number of spew, which are calculated from the information (outer diameter, inner diameter, tyre width and the like) about the tyre to be trimmed previously fed into the control means (sequence controller). For this reason, even if many kinds of tyres of different sizes are supplied at random, the apparatus of the present invention can satisfactorily accommodate and treat them. When the trimming is finished, the chuck 60 reduces its diameter to unchuck the tyre. The unchucked tyre falls to and is carried on by a discharge conveyor 21. According to the methods and the apparatuses of the present invention, the trimming operation can be carried out even for a tyre such as a motorcycle tyre having low rigidity, small tread width and a nearly completely round cross section. further, even if many kinds of tyres of different sizes are supplied, they can be satisfactorily accommodated and treated.

Claims: An automatic spew trimming method wherein a tyre is rotated about its axis, supported from inside and trimmed by a knife characterised by the steps of measuring the outer diameter (b) of the tyre, measuring the width (c) of the tyre, controlling a position (h) to which the tyre is lifted along its rotation axis, based on the measured tyre width (c), determining a rotation centre (f) for a cutter (10) for the tyre tread, based on the measured outer diameter (b) of the tyre, the axis of rotation of the cutter being perpendicular to a plane containing the tyre rotation axis, determining the amount of rotation (g) for the cutter (10) for the tyre tread, based on the measured tyre width (c) and trimming the tyre tread with the cutter (10) based on the determined rotation centre (f) and on the determined amount of rotation (g). A method according to claim 1, characterised by the steps of measuring the bead diameter (a) as the inner diameter of the tyre, measuring the outer diameter (b) of the tyre, measuring the width (c) of the tyre, controlling a position (h) to which the tyre is lifted, based on the measured tyre width (c), a position (d) at which sidewall trimming with a cutter (11) for sidewall trimming is to stop, based on the measured inner diameter (a) of the tyre, determining a position (e) from which sidewall trimming with the cutter (11) for sidewall is to be started, based on the measured outer diameter (b) of the tyre, and trimming the sidewall with the cutter (11), based on the determined sidewall trimming finish position and on the determined sidewall trimming start position. An apparatus for automatically trimming spew comprising a supply conveyor (1) which may supply a tyre to a trimming section (3), including tyre rotation means having a tyre holding mechanism (5) and being positioned at downstream of the supply conveyor (a), the holding mechanism (5) comprises a chuck (60) to support the tyre from the inside of the tyre, a cutter (10) for trimming the tyre tread provided at the tyre rotating section (7), and a discharge conveyor (32) continuing from the supply conveyor (1) characterised by a cutter (11) for a tyre sidewall also provided at the tyre rotating section (7), a tyre measuring unit or section (20) for measuring the inner diameter (a), the outer diameter (b) and the width (c) of the tyre, means for controlling by these measurements the operational positions of the cutters (10,11), the measuring section (20) being positioned in the vicinity of the supply conveyor (1), a controlling means for memorising the data measured by the measuring section (20) and controlling the movements of the cutters (10 and 11), means for moving the tread cutter (10) into contact with the tyre tread and means for rotating the tread cutter (10) by a rotational amount (g) around a rotational centre (f) both determined from the measurements of the inner tyre diameter (a), the outer tyre diameter (b) and the tyre width (c), whereby the cutter rotating axis is perpendicular to a plane containing the rotational axis of the tyre, and means for moving the sidewall cutter (11) into contact with the tyre sidewall and along the sidewall from a trimming start position (e) to a trimming finish position (d).

Inventors: MIKI YOJIRO, NOJIRI YASUSHI, YOSHIDA MASAAKI, MIKI, YOJIRO, NOJIRI, YASUSHI, YOSHIDA, MASAAKI
Applicants: SUMITOMO RUBBER IND, SUMITOMO RUBBER INDUSTRIES LIMITED
Application year: 1992
Main classification: B24B5
IPC codes: B24B5, B29K21, B29D30