GB2082138A - Band inserting mechanism in a banding machine - Google Patents

Abstract

A pair of grooved rollers (17,23), one roller (17) being driven, feed a band (B) between biased band guides (not shown) so as to insert the free end of the band into a band melt-bonding station. The undriven roller (23) is biased by a spring (27) towards the driven roller (17) and is restrained by a stop (28), which can be adjustable to accommodate various widths of band (B). During tensioning, the band (B) pushes the undriven roller (23) away from the driven roller and is thereby released. <IMAGE>

Description

SPECIFICATION Band inserting apparatus for band strapping machine Background of the invention Field of the invention The present invention relates to a band inserting apparatus for a semiautomatic band strapping machine for strapping an article with a plastic band having thermoplasticity in which the end portion of the band after each strapping operation is gripped and inserted into the machine and then the band is automatically tightened around the article and the overlapping portion of the band is melt-bonded.

Description of the prior art The conventional band inserting apparatus comprises a pair of adjacent feed rollers in a machine frame to allow insertion of a band end between the rollers so that the band is fed to a melt-bonding means by the driving of the rollers which clamp both plane surfaces of the band. In the conventional apparatus, it is impossible to insert the band end into an inlet located near the melt-bonding means when a large article is to be strapped. The inlet is, therefore, provided remote from the melt-bonding means and the band is fed with the aid of the feeding function of the rollers to perform the operation. However, it is difficult to feed the band linearly since the band is clamped from their both plane-surface sides by the feeding rollers when the band is fed.The band should be fed so as to actuate accurately a sensitive lever by coming into contact with its end portion to cause the next band tightening and melt-bonding operations in the course of a relatively long path from the feed rollers to the melt-bonding means. However, when a band having a poor linearity is fed along such a relatively long traveling path, the band curves because of a small band-feeding force and a frictional force of the wall of the passage way, thus causing difficulties in the actuation of the sensitive lever by the band end; thereby causing various troubles in an automatic operation apparatus.

In any band strapping machine, it is necessary to release the band automatically from the clamping rollers and the passage way at the time when the band is tightened around the article. The conventional strapping machine has a disadvantage in that it is difficult to release the band automatically from the clamping rollers which calmp both surfaces of the band therebetween.

Summary ofthe invention It is an object of the present invention to overcome the disadvantage of the conventional apparatus and to provide a band strapping machine which has a strong band feeding force while assuring the feeding of the band linearly and can automatically and easily release the band when the band is tightened.

The foregoing and other objects of the present invention have been attained by providing a band inserting apparatus for a band strapping machine which comprises a driving roller and a free roller which are positioned at a distance from a band melt-bonding means, said rollers facing each other with a gap in the same plane as the surface of a band guide member of a strapping machine body wherein a slanted groove is formed in each roller; said free roller is pivotally held on an arm so as to turn around a support shaft; the top end of said arm is normally biased inwards by a spring and a pair of side guides capable of opening and closing are positioned in the same plane as the surface of said band guide at a point downstream of both the rollers.

Said slanted groove can be an angled groove such as a V shaped groove or a partially circular arc groove in cross section.

Brief description of the drawings Figure 1 is a schematic side view of the strapping machine of the present invention; Figure 2 is a side view of an important part of the band inserting apparatus of the present invention; Figure 3 is a front view of the apparatus of Figure 2; Figure 4 is a transversal sectional view of the side guides; Figure 5 is a partially enlarged view of the side guides shown in more detail; Figure 6 is a longitudinal sectional view of the driving roller and the free roller; Figure 7(a) is a side view of the rollers when they are a free state; Figure 7(b) is a plane view of the rollers; Figure 8(a) is a side view of the rollers when they clamp the band; Figure 8(b) is a plane view of the rollers; Figure 9(a) is a side view of the rollers showing a state just before releasing the band;; Figure 9(b) is a plane view of the rollers; Figure 10 is a front view showing a relationship of a pair of guides to a stopper; Figure ii is a cross sectional view taken along b-b line of Figure 10; Figure 12 is a cross sectional view taken along a-a line of Figure 10; Figure 13 is a schematic view showing how the band is fed in an embodiment using a cylindrical driving roller and a cylindrical free roller wherein Figure 13(a) is a side view and Figure(b) is a plane view; Figure 14 is a schematic view showing how the band is fed by the rollers of the present invention wherein Figure 14(a) is a side view, (b) is a plane view and (c) is a cross sectional view of the rollers.

Detailed description of the preferred embodiment Atable (1) projecting horizontally in front of a strapping machine body (3) receives an article (P) to be packaged thereon. A band reel (2) is held in the machine body (3) and a plastic band (B) is unwound from the band reel (2). A vertical band guide (3') is provided in the front of the machine body (3). The band (B) is guided by a series of guide rollers (4), (4) and is pulled backwards by bringing a rocker roller (5') into press-contact with a tightening roller (5). On the other hand, the band (B) is fed forwards by bringing a rocker roller (6') into press-contact with a feed roller (6). A melt-bonding means (7) is provided to melt-bond the overlapping portion of the band (B) and to cut the band.A first gripper (8) grips the band (B) at or near the top end in association with a slide table (9) and a second gripper (10) grips the tightened portion of the band (B) in association with the slide table. A compression head (39) performes the press-bonding of the overlapping ends of the band whose faced surfaces are in a melted condition, by clamping them between the slide table (9) and the compression head.

A motor (11) drives a feed roller (6) through a speed-reducing mechanism (12) and an intermediate pulley (13) and the revolution of the feed roller (6) causes the revolution of the tightening roller (5) through interlocking gears (14), (15). A driving pulley (16) is secured to a shaft which supports the tightening roller (5).

A driving pulley (18) secured to a shaft supporting in turn a driving roller (17) which will be discussed below is driven through intermediate pulleys (19), (19) by means of a round belt (20) by the driving pulley (16) (Figure 2 shows the relation in detail).

A pair of side guide members (21), (21) guide the end portion of the band (B) inserted and both the members (21), (21) are usually biased inward by means of a spring (22) as shown in Figure 4. A sensitive lever (35) positioned at the lower end of the slide table (9) and under the side guide members (21), (21) is actuated by the end of band making contact with the lever to energize a microswitch (35'), thus performing the tightening of the band (B).

The detailed structure of the band inserting apparatus of the present invention will be described according to Figures 5 to 12. The driving roller (17) is positioned facing a free roller (23). An angled groove (17') is formed in the driving roller (17) and an angled groove (23') is also formed in the free roller (23) and the angle of the angled groove (17') is smaller than that of the angled groove (23').

An arm (24), which pivotally supports the free roller (23) on its surface, is pivotted to a main guide (26) with a supporting shaft (25). A spring (27) is mounted between the top end portion (24') and the main guide (26) so that the arm (24) is turnable around the supporting shaft (25) against the action of the spring (27). A stopper (28) is positioned to limit the inward angular movement of the arm (24). The position of the stopper (28) can be adjusted by fastening screws (29), (29) at desirable points in an elongated slot (28').

in Figures 3 and 10, a regularly feeding guide (30) is positioned adjacent to the rear end of one of the side guides (21) to guide the end portion of the band (B) guided by both the side guides (21), (21) without causing irregular movement. The position of the guide (30) can be adjusted by fastening a screw (32) in an elongated slot (31) art a desirable point.

The function and effect of the apparatus of the present invention will be described.

An operator places an article (P) on the table and takes the end portion of the band (B) exposed over the table and inserts it between the driving roller (17) and the free roller (23). Both side edges of the band (B) are clamped between the angled grooves (17') and (23') of both rollers. During the feeding of the band, it is brought into contact with the sensitive lever (35) after passing through the side guides (21), (21) to raise the first gripper (8) of the melt-bonding means (7) so that the end portion of the bond (B) is gripped between the slide table (9) and the first gripper, while the rocker roller (5') is brought into press-contact with the tightening roller (5) to pull the band into a tightening condition.

The tightening of the band (B) causes the arm (24) of the free roller (23) to move outwards around the supporting shaft (25) against the action of the spring (27) as shown in Figure 9(a), (b); thus the band (B) is released from the position between the driving roller (18) and the free roller (23). The band further opens the side guides (21), (21) outwards against the spring (22) (Figure 4) to be exposed whereby the band (B) is directly wrapped around the article (P) to be tightened.

Then, the second gripper is raised to grip the tightened portion of the band (B) in association with the slide table (9) and a heater (not shown) is inserted between the overlapping bands to melt the faced inner surfaces. The compression head (39) is raised to compress the overlapping bands between the slide table (9) and the compression head itself and then the end portion of the tightened portion of the band is cut to complete the melt-bonding operation which can be the conventional method.

In the insertion of the end portion of the band (B) between the driving roller (17) and the free roller (23), the angled grooves (17') and (23') are formed in both the rollers and the angle of the groove of the driving roller (17) is acute compared with that of the free roller (23) so that the band can easily be taken between these grooves since the band (B) enters from a wide path to the narrow path formed by the angled grooves (17'), (23'). The band can be fed downwards by a strong driving force produced by the side edge of the band being brought into contact more strongly with the acute angled groove (17') of the driving roller (17). During the feeding of the band, curving of the band does not occur and the end portion of the linearly fed band (B) naturally comes into contact with the sensitive lever (35) so that the following operations such as tightening, melt-bonding etc. are assured.

The apparatus of the present invention provided with the driving roller (17) and the free roller (23) each having the angled grooves (17') and (23') to assure an easy insertion of the band and a strong feeding action.

The reason for the provision of these elements will be described according to Figure 13(a), (b) and Figure 14(a), (b), (c). In the case of feeding the band (B) by using a cylindrical driving roller (17") and a cylindrical free roller (23"), a band feeding force F' is expressed by: F = FR (1) wherein F is the coefficient of friction and P and Rare roller-pressing force. In other words, F' becomes great depending upon the increase of P. When the roller-pressing force P increases too much, the band (B) is curved as shown in Figure 13(a). It is, therefore, undesirable to increase the band feeding force excessively.

In the embodiment shown in Figure 14 according to the present invention in which the angled grooves (17'), (23') are respectively formed in the rollers (17), (23), the following equations are established: P=2Rsina+2Rcosa = 2R(sin a + Fcos a) P 2(sin a + cos a) Band feeding force F = 2 R = P ..... (2) sin &alpha; + cos &alpha; If the roller-pressing force P is the same in the said equations, the following equation is obtained: F F' = I1 : + cos a When CL = 0.2 and a = 8 for comparison: F: F' = 0.2 : 0.2 sin8 +0.2cos8 = 0.59: 0.2 .-.F3F' Thus, the band feeding force obtained by the apparatus of the present invention is 3 times as strong as that of the conventional apparatus using cylindrical rollers. Accordingly, the roller pressing forces P, R can be small so that a curved band does not occur and a stable feeding operation can be obtained.

As described above, a band insertion apparatus of the present invention assures a strong feeding operation for the band when inserted by clamping the band end portion with slanted grooves such as angled grooves of a driving roller and a free roller. Moreover, since a stable clamping position is obtained, the linearly feeding property for the band is not lost so that the sensitive lever is accurately actuated by the end portion of the band even though the band is passed through longer side guides. The band is fed while both side edges of the band are clamped by the side guides to be easily out of the side guides when the band is tightened so that the following steps of the strapping operation can be certainly performed.

Claims (6)

1. A band inserting apparatus for a band strapping machine which comprises a driving roller and a free roller which are positioned at a distance from a band melt-bonding means, said rollers facing each other with a gap in the substantially same plane as the surface of a band guide member of a strapping machine body, wherein a slanted groove is formed in each roller; said free roller is pivotally held on an arm so as to turn around a supporting shaft; the top end of said arm is normally biased inwards by a spring and a pair of side guides capable of opening and closing are positioned in the substantially same plane as the surface of said band guide at a point downstream of both the rollers.

2. A band inserting apparatus according to Claim 1 wherein said slanted grooves are angled grooves.

3. A band inserting apparatus according to Claim 2 wherein the angle of the angled groove of the driving roller is smaller than that of the free roller.

4. A band inserting apparatus according to Claim 1 wherein said slanted grooves are partially circular arc grooves.

5. A band inserting apparatus according to Claim 1 wherein the end of the side guides near both the rollers is biased outwards by a spring.

6. A band inserting apparatus for a band strapping machine, substantially as herein described with reference to the accompanying drawings.