Apparatus for applying labels to blow molded articles

Abstract: In the forming of an article by blow molding parisons into conformity with cavities of an array of mold sections wherein parisons in the form of tubes are extruded from an extruder into an array of neck molds on a head, the head is moved axially away from the extruder to define the parisons, mold sections are closed about the parisons, and the parisons are blown outwardly, an apparatus for application of labels to the hollow blown plastic articles which comprises an array of vacuum cups mounted on the head and movable with the head and a mechanism operable to move the vacuum cups outwardly to engage labels on magazines and move the labels inwardly toward the head and to thereafter move the labels outwardly and deposit them in the mold cavities when the head moves adjacent the mold cavities. Provision is made for moving the vacuum cups in a controlled slow manner upon removing the labels thereby obviating problems of removing multiple labels or damaging the labels when they are made of material such as plastic.

Description: This invention relates to the application of labels and particularly the application of plastic labels to hollow blown plastic articles. BACKGROUND AND SUMMARY OF THE INVENTION In the making of hollow blown articles such as containers from plastic material, it has heretofore been suggested that labels be held in the cavities of mold sections by vacuum so that when parisons are blown outwardly into conformity with the cavities, the labels become adhered or bonded to the article. In one type of apparatus, commonly known as injection-blow apparatus, parisons in the form of tubes are extruded from an extruder into neck molds on a head. The head includes label handling vacuum devices which remove labels from magazines and deposit the labels in the cavities of the mold sections. One such apparatus is described in Specification US-A-4679997. When the labels are thin and made of plastic, one of the problems is that the vacuum devices tend to remove a plurality of labels at one time and another problem is that the labels can be easily damaged. This problem of multiple labels and label damage where thin plastic labels are used can be obviated by moving the vacuum cups in a controlled slow manner when removing the labels from the source thereof. Such an expedient is disclosed in Specification WO 85/04309, which also suggests moving the vacuum devices at a greater speed when delivering the labels to the mold sections. It is an object of the invention to provide apparatus for forming hollow articles to which labels are attached wherein means is provided for enabling movement of the vacuum devices at the desired speeds. According to the invention, apparatus for forming hollow articles by a method which comprises blow molding parisons into conformity with cavities of an array of mold sections wherein parisons in the form of tubes are extruded from an extruder in an array of neck molds on a head and the head is moved axially away from the extruder to define the parisons and the mold sections are closed about the parisons and the parisons are blown outwardly, wherein the apparatus includes apparatus for applying labels to the hollow blown plastic articles, the label-applying apparatus comprising an array of vacuum devices and means for supporting the array of vacuum devices on the head for movement toward sources of plastic labels when the head is in position adjacent the sources and for movement toward the cavities of the mold sections when the head is adjacent the mold cavities, is characterised in that means are provided for moving the array of vacuum devices into engagement with sources of plastic labels, slowly removing the vacuum devices away from the sources, and thereafter moving the array of vacuum devices between the mold sections, and rapidly moving the devices into the cavities to deliver an array of labels to the cavities; the means for supporting the vacuum devices comprises a shaft having a longitudinal axis and means for mounting the shaft on the head for rotation along the axis, and each vacuum device comprises a yoke pivoted on the shaft and a vacuum block pivoted intermediate its ends on the yoke. Particular embodiments of the invention are set forth in claims 2 to 8 hereafter. Description of the Drawings Fig. 1 is a fragmentary vertical sectional view of a conventional blow molding apparatus to which the invention is applied. Fig. 2 is a view similar to Fig. 1 showing the parts in a different operative position. Fig. 3 is a fragmentary perspective view of the labeling apparatus. Fig. 4 is an end view on an enlarged scale of a portion of the apparatus. Fig. 5 is a sectional view taken along the line 5-5 in Fig. 4. Fig. 6 is a sectional view taken along the line 6-6 in Fig. 4. Description Referring to Figs. 1 and 2, in one type of blow molding apparatus a plurality of parisons in the form of tubes are extruded from an extruder 20 into neck molds 21 on a head 22. As the extrusion continues, the head 22 is moved upwardly relative to the extruder 20 to define parisons P. Mold sections 23 define an array of cavities C which are then closed about the parisons and the parisons are blown outwardly to form hollow articles such as containers. If labels are applied to the cavities of the mold sections before they are closed, the labels become adhered or bonded to the hollow blown article that is formed. Two arrays of label pickup devices 25 supporting vacuum cups V, as hereinafter described, are provided on the head 22 for movement relative to the head such that the vacuum cups V can be moved outwardly relative to the head 22 to remove the labels L from magazines M; thereafter inwardly in order that the head may be moved downwardly between the mold sections; whereupon once again the vacuum devices can be moved outwardly to deposit the labels in the mold cavities C where vacuum in the mold cavities holds the labels until the mold sections 23 are closed and the parisons P are expanded to define hollow articles. In accordance with the invention, provision is made for controlling the speed of movement of the vacuum devices. It has been found that if the vacuum devices are moved to engage the labels in the magazines and thereafter slowly moved away from the magazines, the problems of removing multiple plastic labels from the magazines or damaging the plastic labels are obviated. However, in order to efficiently produce containers in the shortest possible time, provision is also made for moving the label pickup devices rapidly outwardly to deposit the labels into the mold cavities C. Referring to Figs. 3-6, each vacuum pickup device 25 comprises a vacuum cup arm assembly comprising a bracket 26, a pivot yoke 27 pivoted to the bracket 26 by a shaft 27a and yieldingly urged to a vertical position by coil springs 28 on shaft 27a having their ends engaging the bracket 26 and the yoke 27, respectively. A vacuum cup block 29 is pivoted intermediate its ends on yoke 27 by a pin 30 and supports the vertically spaced vacuum cups V. Each vacuum cup block 29 includes a vacuum inlet 31 which communicates with a longitudinally extending passage 32 that extends to transverse passages 33 in the vacuum cups V. Each array of vacuum cup arm assemblies 25 is mounted on a shaft 35 that is rotatably mounted on brackets 36, 37 mounted on the side of head 22. The two shafts 35 and the two arrays are interconnected by a connecting link 38 that is pivoted to lever arms 39, 40 that are fixed on the respective shafts 35. In accordance with one embodiment of the invention, a stepping motor S is mounted on a bracket and has an output shaft 41 supporting a gear 42 meshing with a gear 43 fixed on one of the shafts 35. The motor is operated in accordance with the invention at different speeds during different portions of the cycle. At the time that the vacuum cups V are in position adjacent the magazines M, the stepping motor is operated at a high speed to bring the vacuum cups V into engagement with the labels L and then reversed and operated at a lower speed sufficient that only a single label L will be removed from each magazine M and that the labels will not become damaged. When the head 22 with the array of vacuum pickup assemblies 25 thereon is moved between the open mold sections 23, the stepping motors are operated at a high speed to rapidly move the labels L within the mold cavities C and deposit them therein. The label pick-up devices must move fast after the label has been deposited in the cavities to minimize total cycle time. The pivoting of the vacuum cup blocks on the pivot yoke 27 permits the vacuum cups V to move and align with the stack of labels L in the magazines M and with the base of the cavities C in the mold sections. The pivoting of the yoke 27 on the brackets 26 together with the springs 28 permits the vacuum blocks 29 on one side of head 22 to engage the magazines or cavities before the vacuum blocks 29 on the other side thereby obviating the need to precisely locate the various parts relative to one another. The overtravel of the mechanism on side B (Fig. 3) permits the mechanism on side A to come into contact with the mold cavities or magazines on side A before the mechanism on side B contacts the cavities or magazines. This permits one stepping motor to drive both the side A and B mechanisms and guarantees that the label pick-up devices will all make contact with all the labels in the magazines and all the mold cavities. This overtravel combined with the springs on the yoke permit some lost motion of the vacuum blocks relative to each other. As shown in Figs. 5 and 6, the outer surfaces O on the vacuum blocks are provided with a taper that extends axially downwardly and inwardly toward the vertical axis of head 22 in order that there will be an effective label clearance with respect to the mold 23. More specifically, when the blocks 29 are in the transfer position, shown in broken lines in FIG. 6, the surface O contacts the head 22 tilting the label L downwardly and inwardly relative to the head 22 such that the label L clears the mold. In a typical example, the operating speeds for plastic labels are as follows: Head 22 is up vacuum pick up assemblies 25 out 20,000 steps/sec for 450 steps (Picking label) vacuum pick up assemblies 25 back with labels 25 steps/sec for 400 steps, then at 1000 steps per sec for 50 steps Head 22 down vacuum pick up assemblies 25 out 2,000 steps/sec for 600 steps (Placing label) vacuum pick up assemblies 25 back 20,000 steps/sec for 600 steps Minimum speed is 25 steps/sec. for the stepping motor. Maximum speed is 20,000 steps/sec. for the stepping motor. It can thus be seen that there has been provided a method and apparatus for supplying plastic labels which obviates the problems of the prior art, namely, the problem of multiple labels being removed from the magazines and damage to the labels when they are made of plastic. The use of a stepping motor permits a wide choice of exactly controlled speeds to be selected to accommodate the physical characteristics of any label.

Claims: Apparatus for forming hollow articles by a method which comprises blow molding parisons (P) into conformity with cavities (C) of an array of mold sections wherein parisons in the form of tubes are extruded from an extruder (20) in an array of neck molds (21) on a head (22) and the head is moved axially away from the extruder to define the parisons and the mold sections are closed about the parisons and the parisons are blown outwardly, wherein said apparatus includes apparatus for applying labels to the hollow blown plastic articles, said label-applying apparatus comprising an array of vacuum devices (25), and means (26, 35) for supporting said array of vacuum devices (25) on said head (22) for movement toward sources (M) of plastic labels (L) when the head is in position adjacent the sources and for movement toward the cavities of the mold sections when the head is adjacent the mold cavities, characterised in that means (S) are provided for moving said array of vacuum devices (25) into engagement with sources (M) of plastic labels, slowly removing the vacuum devices away from the sources, and thereafter moving the array of vacuum devices between the mold sections, and rapidly moving the devices into the cavities to deliver an array of labels (L) to the cavities; wherein said means for supporting said vacuum devices comprises a shaft (35) having a longitudinal axis and means for mounting said shaft on said head for rotation along said axis, and wherein each vacuum device (25) comprises a yoke (27) pivoted on said shaft (35) and a vacuum block (29) pivoted intermediate its ends on said yoke. Apparatus as claimed in claim 1 wherein said means for moving said vacuum devices comprises a stepping motor. Apparatus as claimed in claim 1 or 2 including spring means (28) operable to urge said yoke in one direction relative to said shaft. Apparatus as claimed in claim 3 wherein each said spring means comprises a coil spring (28). Apparatus as claimed in any of claims 1 to 4 including a second array of vacuum devices, means for supporting said second array of vacuum devices on said head for movement toward a second source of labels when the head is in position adjacent the sources and for movement toward the cavities of the mold sections when the head is adjacent the mold cavities, and means interconnecting said first and second array for substantially simultaneous movement, said means for supporting said second array of vacuum devices comprising a second shaft having a longitudinal axis, means for mounting said second shaft on said head for rotation along its axis, and each second vacuum device comprising a second yoke pivoted on said second shaft, and a second vacuum block pivoted intermediate its ends on said second yoke. Apparatus as claimed in claim 5 including second spring means operable to urge said second yoke in one direction relative to said second shaft. Apparatus as claimed in claim 6 wherein each said second spring means comprises a second coil spring. Apparatus as claimed in any of claims 1 to 7 wherein each said vacuum block (29) includes a tapered surface (O) which engages the head (22) during transfer causing the label (L) to extend downwardly and inwardly relative to the head and thereby provide proper clearance with respect to the mold.

Inventors: AMES GERALD L, PLENZLER JOHN A, AMES, GERALD L., PLENZLER, JOHN A.
Applicants: OWENS ILLINOIS PLASTIC PROD, OWENS-ILLINOIS PLASTIC PRODUCTS INC.
Application year: 1989
Main classification: B29C49
IPC codes: B65C3, B29C49