MACHINE FOR MANUFACTURING BLOWN GLASS BODIES, WITHOUT MOLDS, BY MEANS OF PNEUMATIC MANDRELS

Abstract: A blowing machine for automatic production of hollow glass bodies, especially for Christmas ornaments, starting from a glass tube, by using heat and traction, characterized by free blowing without molds and by two mandrels one for feed (10) and the other for traction (40) that determine a grip on the glass tube (35) - (71) and connection with the blower (85) by means of pneumatic contraction of coaxial elastic tubes in order to make possible achievement of the sensitivity and effectiveness of manual production and therefore obtain hollow bodies (70), (94') of a quality not inferior but, at the same time, much less costly.

Description: DESCRIPTION Title; * MACHINE FOR ANUFACTURING BLOW GLASS BODIES, WITHOUT A MOLDS, BY MEANS OF PNEUMATIC MANDRELS 5 Technical field The above invention concerns the production of hollow glass bodies, used especially as Christmas ornaments, by means of blowing. Present techniques 10 The hollow glass bodies referred to above must, as is known, be as light and as lustrous as it is possible to make them while the blowing aperture must be of minimum size. For these reasons it is at present preferable to make them 15 by hand using glass tubes for the purpose. The tube is made to spin while being heated by a burner to obtain bulb-shaped bodies each of which has an appendix or tail at its end. The bulb so obtained is then heated to melting point and is 20 then swollen to the desired size by blowing through the tail. Glass blown in a free environment acquires a high surface lustre and its appearance is exactly that required for the product. 25 The cost of making hollow glass balls by hand is however very high and often prohibitive. Another process is realizable by mechanical means but this * one requires the use of molds into which the hollow body is blown. 30 The cost of this process is much lower but it gives an in¬ ferior quality product in no way comparable to that obtain¬ able by the manual process. By means of the above invention the hollow bodies con¬ cerned can be made mechanically and almost automatically but possessing a quality comparable to that obtainable by manual processes at considerably lower costs as will be de- scribed below. Description of the invention The machine subject of the invention produces hollow bodies detaching one after anothe ' r, by heat and traction, drawn segments of a glass tube and then blowing them up when stLll hot in a free environment without making use of molds. For these operations the machine comprises two aligned man¬ drels, one for feed and the other for blowing. These mandrels cause the glass tube to be firmly held by pressure, generated by a fluid, especially air, exerted on it by soft bodies such as rubber tubes and the like which surround the glass tube. Action on the glass tube and on the hollow body formed from it is therefore taken with about the same degree of sensi- vity, gentleness and strength as would be applied by the hands and mouth of a specialized glass blower. The feed mandrel rotates, around its longitudinal axis, in relation to a cylindrical casing supported by a sliding car riage that moves along a longitudinal guide fixed to the bed of the machine. Said mandrel comprises a rigid axial tube, in whose walls there are holes in substantially opposing positions, the glass tube passing through the rigid tube. This latter tube is surrounded by an elastic tube, of rubber and the like, which is sealed and is in turn surrounded by- a ring-shape chamber. Ihtioduction of!' compressed air into this chamber makes possible centripetal contraction of the elastic tube , expansion of - 3 - areas of said elastic tube through the holes in the sides of the rigid tube causing said areas to exert pressure on the glass tube such as will keep it fixed to the mandrel. The blowing mandrel rotates around its longitudinal axis in 5 relation to a cylindrical casing supported by an upright part of the machine. Said mandrel comprises a sealed elastic tube, of rubber and the like which surrounds the drawn end of the glass tube in troduced into the mandrel, said elastic tube being in turn 10. surrounded by a ring-shaped chamber. By letting compressed air into said chamber it is possible to cause centripetal contraction of the elastic tube and therefore pressure by its intermediate part on the drawn end of the glass tube in such a way as to keep it fixed to the mandrel. 15 There is an axial duct on a hind part of the mandrel, said duct being connected to a pipe for blowing in air. The back end of the elastic tube is fixed to a cylindrical expansion which lengthens the above duct without interrup¬ tion. 20 Therefore, by shrinkage of the elastic tube round the end of the glass tube a hermetic seal is created between the latter and the pipe for blowing in air. Sequence of operations Each sequence of operations takes place substantially as 25 follows. Starting from its front end stop and gripping the glass tube the feed mandrel moves towards the blowing mandrel into which it introduces the drawn end of said tube which is then gripped by said blowing mandrel. 30 When the length of tube betv/een the two mandrels has been heated by a burner to melting point, the feed mandrel moves backwards and in so doing stretches said length of tube. The burner moves to a point lying between the end of the stretched length of the tube and that part of it held by the blowing mandrel. When the glass has reached melting point the feed mandrel moves still further back to the end of its stroke and in doing so separates the stretched length from that part of the tube held by the blowing mandrel. That part of the tube remains closed like an ampoule and when it has been sufficiently heated by the burner, the blowing pipe is con- nected to a blowing device which swells the ampoule to the desired size. At this point an expeller extracts the completed hollow body while a cutter cuts off the molten tip of the drawn length of glass tube. A new sequence, similar to the previous one, can then be automatically repeated. The characteristics and purposes of the invention will be made even clearer by the following example of its execution illustrated by diagrammatical drawings. Example of execution Figures 1 to 5 show side views of the blowing machine, sub¬ ject of this present invention, in its various functioning stages. Fig. 1. End of a sequence with extraction of the finished ampoule. Fig. 2. Start of a fresh sequence. Fig. 3. Stretching stage. Fig. 4. Separation of the tube from the ampoule being formed. Fig. 5. The tip of the tube is cut off and the ampoule co - pieted. Fig. 6. Cut-through view of the pneumatic tube -feed mandrel at the beginning of a new sequence . Fig. 7. Cut-through view of the pneumatic blowing mandrel . with an ampoule in progress of formation. The machine (Fig. 1) comprises a bed 75 with a fixed guide bar 16 supported by uprights 77 and 78. The carriage 80 can slide along the bar, and fixed to said carriage is the arm 81 which supports the tube-feed mandrel 10 (see also de_ tail in Fig. 6) that grips the glass tube 35 with its drawn out end 71. At the end 82 of the bar the carriage 83 can slide andfixed to said carriage is the vertical arm 84 which supports the air blower 85. The upright 78 supports the mandrel 40 for blowing up hol¬ low bodies (shown in detail in Fig. 7) while gripping the ampoule 70,with stretched out appendix 69, in progress of formation. At the base of the upright there is a bushing 86 inside of which can slide the rod 87 that supports the burner 88 at one end. The V-shaped cam 89 is fixed to the carriage 80 and the le- vers 90 and 91 are placed in the path of the cam. •The expelling device 96, supported and guided by the trans¬ lating rod 97, fitted with pincers 98, is also mounted on said upright. Below the expeller a conveyor belt 99 rests on the bed of the machine. On the machine's upper cross piece 100 there is the cutter 101, with tools 102 and 103, fixed to the rod 104 sliding vertically in the bushing 105 fixed to the cross piece. The gas 106, oxygen 107 and air 108 regulating devices can be seen on the right hand side of the machine as well as the knob 109 which controls opening of the mandrel 40. On the left hand side of the machine there is the knob 110 for opening the mandrel 10. Figs. 6 and " 7 respectively show in greater detail, the feed mandrel 10 and the blowing mandrel 40, both pneumatically operated. 5 The feed mandrel 10 comprises a cylindrical casing 11 fixed by means of arm 81 to the guide bar 76 mounted on the bed 75 of the machine Inside said casing 11 and resting on roller bearings 12 and 13 " „ there is sleeve 14 to which is fixed the crown wheel 15 10. through which connection is made to an electric motor, not shown in the figure, needed for rotating the mandrel 10. Disc 37 is screwed on to the other end of the sleeve. Sleeve 14 houses the alluminum tube 73 fixed to the sleeve by means of bushings 16 and 17 with their respective anular 15 channels 21 and 21' for washers 18 and 19. Between the aluminum tube 73 and the sleeve 14 an elastic tube 22, of rubber and the like, is inserted and is forced at, its two ends onto the ring-shaped reliefs 23 and 24 res¬ pectively fixed to the bushings 16 and 17. 0 Holes- 25, 26, 27 and others are made in the sides of the tube 73. The ring-shaped washers 38 and 39 are placed between the ca sing 11 and the above sleeve. A connector 28 is mounted on the side of the casing 11,for 5 letting in compressed air which, through the ring-shaped ca vity 29 and a series of holes, such as 30, passes into the ring-shaped cavity 31 causing zones of tube 22, such as 32, 33, 34, to press down into the holes 25, 26, 27 and these depressed zones grip the glass tube 35 inserted into the al 0 uminu tube 73. The glass tube is thus firmly held butwith the same sensitivity, gentleness and strength as it would be in the hands of a skilled glass blower. The pneumatic mandrel 40 (Fig.7 ) for the object to be blown comprises a cylindrical casing 41,fixed to the up¬ right 78 of the bed 75,that houses inside it, by means of the roller bearings 42 and 43, the sleere 44 fixed to which is the crown wheel 45 for connection to an electric motor, not seen in the drawing, needed for rotating the mandrel. Fixed to the other end of the sleeveis the ring-shaped disk 46 on which is mounted the pipe 48 by means of the disk 47 and screws 53, 54. At one end of said pipe there is a mouth 49 for insertion of the interchangeable bushing 50 that can be fixed by means of the transversal screw 51,and on the inside a cylindrical expansion 52 coaxial with the mandrel. By means of screws 55, 56, the disk 57 is fixed to the crown wheel 45, said disk comprising externally the threading 74 for fitting on the pipe 58 connecting to the air blowing mouth and having on the inside the cylindrical body 59 with the cylindrical expansion 60 counterposed to the cylindrical expansion 52 of the pipe 48. Said body is provided with the through hole 61 coaxial with the mandrel. The ring-shaped washers 62 and 63 are placed between the ca sing 41 and the sleeve 44. On the side of the casing 41 a connector 64 is mounted for letting in compressed air which, through the ring-shaped ca vity 65 and a series of holes like 66, passes into the ring- -shaped cavity 67 which is created between the elastic rub¬ ber tube 68 inserted at its ends respectively in the axial and counterposed cylindrical expansions 52 and 60 and inside the sleeve 44. The air blown in thus causes the elastic tube 68 to shrink onto the stretched end 69 of the glass tube from which the - 8 - blow body is formed with the same sensitivity, gentleness yer firm handling typical of the skilled glass blower. The interchangeable bushing 50 has its inside part of re- fractary material 115 so as to withstand the high tempera- tures of the glass tube and especially of the ampoule 70 being formed by the blown air. A drive unit with cam shaft worked by an electric motor and adequate mechanisms, served by pneumatic cylinders, regu¬ lates the movements of the various mechanical parts. : Thei mandrels and the conveyor belt are moved by electric mαtrαrs. A central control unit, with shutter vanes and with mecha¬ nical and pneumatic devices, ensures operation of all parts even in the worst environmental conditions. ' For the sake of simplicity this equipment is not shown in the drawings because the techniques of such equipment are already well known. Operation At ! the end of each sequence the machine appears as drawn in Fig. 1. The ampoule 70 with its terminal appendix 69 is expelled from the mandrel 40, which opens for the purpose, by means of. the expelling device 96 fitted with pincers 98. The am¬ poule falls down onto the conveyor belt (99). The figure shows the ampoule 70' from the preceding sequence while it is about to be carried away on said conveyor belt. If. the automatic repetition switch has been turned on the new sequence begins immediately after the ampoule has fal¬ len or else it does so if a special control device has been worked. To start a series of sequences , the mandrel 10 must be moved to its position in Fig.1 against its limit stop 111. - 9 - Lever 110 is moved to open the mandrel manually, the tube of glass, like 35 with it stretched end 71, is inserted and the mandrel is then closed. The various sequences take place as follows: Phase one The carriage 80 move3 the mandrel 10 with its glass tube 35 until the extremity 71 of the tube has penetrated inside the mandrel 40 which then closes. The burner 88 moves to position "3" marked by 112, and then lights up (Fig.2). The mandrels rotate continuously driven by the electric mo¬ tors by means of crown wheels 15 and 45. Phase two The mandrel 10 opens, makes a short backward movement until the lever 91 is lowered by the cam 89 and then closes again leaving between it and mandrel 40 a length 93 of tube equi- valent to thea ount needed to form the hollow blown body. Phase three The burner extinguishes itself when the flame has brought the glass to melting point. The mandrel 10 moves further back, until the lever 90 is lowered by the cam 89, together with the tube 35, part 93 of which is stretched (Fig. 3). Phase four The burner moves onto position N° 2, indicated by 113, and lights up heating the junction 93' between part 93 and part 94 fixed to the mandrel 40. The mandrel 10 moves back to its limit stop 111 and in so doing separates the two said parts 93 and 94 (Fig. 4). Phase five The burner extinguishes itself. As a consequence of the movement of carriage 83, the air blower 85 is inserted into pipe 58 of the mandrel 40 and blows up the "drop" of glass formed at the end of part 94 still gripped by the mandrel 40. Phase six The air blower detaches itself from pipe 58. The burner moves onto position N° 1, indicated by 114, and lights up. Phase seven The burner extinguishes itself. The blower is once again inserted into the pipe and blows in such a way as to transform piece 94 into the spherical ampoule 94'. The cutter 101 moves down and cuts through the tip 93' ' (Fig. 5). The expeller 96 expels the ampoule 94' which falls onto the conveyor belt as shown in Fig. 1 for ampoule 70'. The sequence can then start again repeating the phases de cribed above. ' Advantages Hollow glass bodies, especially those used as Christmas ornaments, formed automatically, without molds, with the same sensitivity and efficiency as if made by the hand and lips of a glass blower and therefore possessing, like those formed by hand, maximum specific lightness and brilliance, minimum blowing aperture dimensions, optimum qualities gen erally but at drastically lower costs. As the applications of the invention have been described as approximate examples only and not limited to these, it is understood that any equivalent application of the inven tive concepts explained and any product executed and/or in operation according to the characteristics of the invent±αi will be covered by its field of protection.

Claims: C L A I M S 1. A blowing machine for automatic production of hollow glass bodies especially used for Christmas ornaments, star ting from glass tubes, characterized in that said bodies (70), (94* ) are made by detaching, one after another, by means of heat and traction, drawn segments (71), (69) of glass tubes (35) and blowing them under heat in a free en¬ vironment, without molds, by the use of two aligned man¬ drels (10), (40), one (10) a feed mandrel and the other (40) a blowing mandrel,which cause the glass tubes (35), (71), (69) to be firmly held by pressure, generated by a fluid, air especially, from soft bodies such as rubber tubes (22), (68) and the like, thus making it possible to handle the glass tube (3 )-(7l),- (69) and the hollow bodies (70), (94') with almost the same sensitivity, gentleness and strength as that exerted by the hand and mouth of a skilled glass blowing worker. 2. A blowing machine for automatic production of hollow glass bodies especially used for Christmas ornaments,start ing from glass tubes, as in claim 1, characterized in that the feed mandrel (10), rotating axially in relation to the casing (11) supporting it, comprises a rigid axial tube (73),in the sides of which there are substantially counter posed holes (25), (26), (27), through which passes the glass tube (35) surrounded by an elastic hermetically - sealed tube (22) in turn surrounded by a ring-shaped cham¬ ber (31) so that, by letting compressed air into this lat¬ ter, it is possible to cause centripetal contraction of the elastic tube (22), expansion of the elastic tube into and through the holes (25), (26), (27) of the rigid tube(73) so that zones (32) , (33) , (34) of the elastic tube exert pressure on the glass tube (35) sufficiently to keep it firmly held by the mandrel (10). 3. A blowing machine for automatic production of hollow glass bodies especially used for Christmas ornaments,star¬ ting from glass tubes, as in claim 1, characterized in +Jhat - the blowing mandrel (40), rotating axially in relation to the supporting casing (41), comprises an elastic tube (68), of rubber and the like, that surrounds the stretched out extremity (59), (71) of the glass tube, placed in the man¬ drel, the tube (68) being in turn surrounded by a hermeti- cally sealed ring-shaped chamber (65), so that by letting compressed air into said chamber it becomes possible to ob tain centripetal contraction of the elastic tube (68) cau¬ sing it to press sufficiently on the stretched extremity (69), (71) of the glass tube to fix it firmly to the man- drel (40) on whose posterior body (59) there is an axial duct (61) connected to a pipe (58) for blowing air, the po sterior end of the elastic tube * (68) with cylindrical ex¬ pansion (60) continuously extending the above duct (61), ensuring, by shrinking the elastic tube (68) round the ex- tremity (69), (71) of the glass tube, a hermetic seal be¬ tv/een said extremity and the air blowing pipe (58). 4. A blowing machine for automatic production of hollow glass bodies, used especially for Christmas ornaments,star ting from glass tubes, as in claim 1, characterized in t_hat, to make a working sequence, the feed mandrel (10) grip¬ ping the glass tube (35), (71), moves towards the blov/ing mandrel (40) and inserts into it the stretched extremity (71) of said tube (35) which the latter mandrel (40) rips, then, the length (93) of tube (35) between the two mandrels (10) and (40) having been heated by a burner (88) to melt¬ ing point, said mandrel ( 10) moves backwards stretching said length (93) of the tube (35) between the two mandrels when, the burner (88), moved onto point (93') between the end of * the stretched length (93) and that part (94) of the tube (35) held by the blowing mandrel (40) ,having brought the glass to melting point, said mandrel (10) is moved further backwards to the end of its stroke separa¬ ting the stretched length (93) from the part (94) held by the blowing mandrel (40) , said part remaining closed like an ampoule, the blower (85) ,when said part has been suffi¬ ciently heated by the burner (88), blowing it up, through the mandrel (40),to the required size, an expelling device (96) then expelling the completed ampoule (94 1 ), a cutter (101) then cutting off the molten tip (93") of the length (93) of glass tube (35), thus making possible execution of a fresh sequence like the preceding one.

Inventors: ZANI GIULIO, ZANI, GIULIO
Applicants: ZANI GIULIO, ZANI, GIULIO
Application year: 1986
Main classification: C03B23
IPC codes: C03B23