Hydraulic steel strapping machine

A hydraulic steel strapping machine for strapping a steel strip around a package, including a clamping and cutting section and a tensioning section. An objective of the present invention is to minimize the weight and the volume of the steel strapping machine. The clamping and cutting section comprises a clamping cylinder, disposed on a top position of a front end of the hydraulic steel strapping machine along a Z direction and supported by a support frame, for driving a linkage mechanism. A cylinder pin is disposed in the linkage mechanism along a X direction and is sleeved by a lifting lug fixed onto a bottom surface of a piston of the clamping cylinder. A pressing part is sleeved around the cylinder pin, a cutter, a return spring and a transverse cutter are disposed below the pressing part. The linkage mechanism comprises two groups of connecting rods.

FIELD OF THE INVENTION

The invention belongs to the class of general pressure machine, and specifically relates to a hydraulic steel strapping machine for strapping a steel strip around a package, including a clamping and cutting section and a tensioning section.

BACKGROUND OF THE INVENTION

The known steel strapping machines mainly utilize pneumatic cylinder to, tension, clamp and cut a steel strip. However, as compared with a hydraulic cylinder, a pneumatic cylinder produces smaller tension and clamp strength, and hence requires larger cylinder capacity, leading to weight disadvantage.

Since steel strapping machines are used at a wide variety of locations, they are often handled manually and moved, for example, to various usage sites. From such point of view, it is very important that the machine causes minimal physical loads for users.

BRIEF SUMMARY OF THE INVENTION

An objective of the present invention is therefore to minimize the weight and the volume of the steel strapping machine.

The present objective could be achieved according to the present invention by virtue of the fact that the clamping and cutting section and the tensioning section are both driven by the hydraulic cylinders.

The present invention is advantageous in that the driven power is provided by three hydraulic cylinders. Particularly, the clamping and cutting section has a clamping cylinder, while the other two parallel tensioning cylinders belong to the tensioning section. The hydraulic cylinders have a small volume and light weight, demonstrating their volume and weight benefits. Moreover, the output of hydraulic cylinders is much larger than that of pneumatic cylinders, applying a larger deforming force on a buckle and a steel strip. As a result, a thicker steel strip could be used to strap around a package.

In a preferred embodiment of the present invention, the clamping cylinder is disposed on the top portion of a support frame, driving a linkage mechanism along the Z direction. A cylinder pin of the clamping cylinder is disposed in the linkage mechanism along the X direction, and is sleeved by a lifting lug fixed on the bottom surface of the piston of the clamping cylinder. A pressing part is sleeved around the cylinder pin. A cutter, a return spring and a transverse cutter are placed below the pressing part.

As mentioned above, the linkage mechanism includes one group of connecting rods. The group has four connecting rods. The two higher connecting rods are sleeved around the cylinder pin of the clamping cylinder, while the other ends are connected to the two lower connecting rods movably about the X axis. The edges of the two lower connecting rods of the four connecting rods bite against a buckle and a steel strip inside the buckle at two bite points, with one bite point on each edge, deforming the buckle and subsequently clamping the steel strip firmly. In order to increase the clamp strength, the linkage mechanism includes a plurality of parallel groups. In one preferred embodiments, the amount of the group is two.

Along the X direction, the distance between the back surface of the buckle and the cutter is 3-10 mm.

In terms of design, the tensioning section includes two tensioning cylinders, increasing the pre-tension strength applied to a package. Also, these two cylinders may be parallel to each other, so as to decrease the unbalanced load on the tensioning cylinders. In this way, the tensioning cylinders are more endurable.

Moreover, a tensioning mechanism disposed between these two tensioning cylinders comprises an eccentric wheel, a tensioning spring and a kicker pin. The piston rod of each of the tensioning cylinders is fixed onto the two ends of a back rest along the Y direction. Two side rests are disposed along the X direction. A first end of each of the side rests is fixed on the back rest, while a second end sleeves on an end of the pin of the eccentric wheel. The end of the steel strip is pressed by a clamping tooth of the eccentric wheel and a working surface of a supporting table disposed under the eccentric wheel. The kicker pin is disposed to abut against to the eccentric wheel. The two ends of the tensioning spring are tied to the two side rests respectively, and the tensioning spring passes through a hole of the eccentric wheel.

The tensioning cylinders are reversible in terms of their direction of drive. As a result, the tensioning mechanism could be driven in the same direction. When the tensioning cylinders extend, the eccentric wheel would press the steel strip together with the working surface of the supporting table to provide a strong pressure thereon. Consequently, the eccentric wheel allows the thickness of steel strip to be 0-1.5 mm. The kicker pin is disposed to abut against to the eccentric wheel. When back rest gets closer to the kicker pin, the stress on the steel strip would disappear due to the movement of the eccentric wheel.

Moreover, a guide bar is disposed on the surface of the two tensioning cylinders respectively, distributing the stress on tensioning mechanism evenly and extending the operation life of the machine.

In a preferred embodiment, a hinge system is designed to facilitate placement of the steel strip into the hydraulic steel strapping machine. The hinge system is disposed on the front end of the two tensioning cylinders in the axial direction. The hinge system includes a hinge pin disposed along the Y direction, a cutter frame, and a hinge return spring. The hinge pin is fixed on the rear end surface of the back plate of the support frame by two trunnion seats disposed along the Y direction. The cutter frame includes two side frames and a cutter platform under the side frame. The side frames am respectively fixed onto the two tensioning cylinders along the X direction and are sleeved around the two ends of the hinge pin through a hole drilled on the side frame. The back end of the hinge return spring is disposed in a spring hole of the cutter frame.

As the steel strip is cut by the cutter, the tension disappears. The tensioning section consequently gets away from the clamping and cutting section, forming an angle δ between the axis of tensioning cylinders and the X axis via the hinge system. As a result, users could take out the steel strip easily. Then a new steel strip containing a buckle is placed between the eccentric wheel and the working surface of the supporting table. Making the angel δ be zero, and the buckle is therefore located between the edges. When the steel strip is tensioned, the front end of the cutter frame contacts the rear end surface of the back plate of the support frame. Meanwhile, the hinge return spring compresses in the spring hole disposed on the cutter frame.

In another embodiment, the working surface of the supporting table is flat plane or serrated plane, while the surface of the steel strip contacting the working surface is serrated plane, so as to increase the friction. The hardness of the steel strip is equal to or larger than 85 HRB (Rockwell B scale).

In one preferred embodiment, the clamping cylinder is a single acting hydraulic cylinder. In order to further improve the efficiency of the champing cylinder, in one embodiment, the clamping cylinder is a double acting hydraulic cylinder. The maximum output of the clamping cylinder is 4.5 t (tons).

Moreover, in on embodiment, the tensioning cylinders is single acting hydraulic cylinders or double acting hydraulic cylinders. The maximum output of the tensioning cylinders is 4.0 t. And the tension strength could therefore increase significantly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The clamping and cutting section:

InFIG. 1, the hydraulic steel strapping machine in perspective view could be seen. A clamping cylinder1is disposed on the top portion of the front end of the hydraulic steel strapping machine along the Z direction. Beneath the clamping cylinder1is here found a support frame2. InFIG. 2, the support frame2comprises a front plate2.2and a back plate2.1. The linkage mechanism has two groups of connecting rods, the front group3.2and hack group3.1. InFIG. 6andFIG. 9, the linkage mechanism sets a cylinder pin3.3along, the X direction. The cylinder pin is sleeved by a lifting lug1.2fixed on the bottom surface of the piston1.1of the champing cylinder1. InFIG. 9, the back end of the cylinder pin3.3is sleeved by a pressing part3.4, below which a cutter3.6, a return spring3.7and a transverse cutter3.8are disposed. The steel strip could be cut by the cutter3.6together with the transverse cutter3.8.

The edges3.21and3.22of the lower ends of the lower connecting rods are shown inFIG. 6. When the piston1.1of clamping cylinder moves down, the cylinder pin3.3is driven via the lifting lug1.2. In this way, two opposite edges constitute a lock to clamp the buckle4and the steel strip5, creating two bite points4.2on the buckle4, as shown inFIG. 7. InFIG. 7, because of two parallel groups of connecting rods, two other bite points4.1are created. InFIG. 9andFIG. 11, the distance between the back surface4.3of the buckle4and the cutter3.6along the X direction may be 3-10 mm.

InFIG. 9, after the clamping cylinder1is switched on, the piston1.1of the clamping cylinder moves down, driving the cylinder pin3.3to move downward in the slot2.3of the front plate and back plate. The opposite edges move toward each other and create bite points4.1and4.2on the buckle, as shown inFIG. 7. The buckle4and the steel strip5are subsequently clamped firmly. Then the pressing part3.4is driven by the cylinder pin3.3, and presses the cutter3.6. The steel strip5could be cut by the cutter3.6together with the transverse cutter3.8. Finally, the piston of the clamping cylinder moves up. The linkage mechanism and the pressing part return to their initial positions. Without the pressure produced by the pressing part3.4, the return spring3.7brings the cutter3.6back to the limited rod3.5.

The clamping cylinder1is a single acting hydraulic cylinder and the maximum output thereof is 4.5 t.

The tensioning section:

InFIG. 5, along the Y direction, the steel strip5and a tensioning mechanism7are disposed between two tensioning, cylinders6.1and6.2. Two piston rods6.11and6.21of the tensioning cylinders are fixed on the two ends of a back rest6.3along the Y direction. Along the X direction, two side rests6.4are disposed. A first end of each of the side rests is fixed on the back rest, while a second end is sleeved onto the end of the pin6.5of an eccentric wheel7.1, so as to increase the friction and subsequently the tension on the steel strip5. A guide bar6.1A and6.2A is disposed on the surface of each of the tensioning cylinders, allowing the side rests6.4to be reciprocal movable along the X direction.

InFIG. 10, the end of the steel strip is pressed by a clamping tooth of the eccentric wheel and the working surface6.6A of a supporting table disposed under the eccentric wheel. In order to enable the tensioning cylinders to drive the eccentric wheel, the two ends of a tensioning spring7.2are tied to the two side rests respectively, and the tensioning spring threads the hole of the eccentric wheel.

Both of the tensioning cylinders are double acting hydraulic cylinders whose maximum output is 4.0 t. The high output provides a strong tension that enables users to utilize a relatively thick steel strip5. The thickness of the steel strip5is 0-1.5 mm.

An oil line6.7of the tensioning cylinders could be seen inFIG. 5.

InFIG. 10, a kicker pin7.3is disposed against the eccentric wheel. When the back rest6.3gets closer to the kicker pin, a slot would form between the clamping tooth and the working surface. In this way, the steel strip could be placed conveniently.

InFIG. 5, when actuating the tensioning cylinders, the back rest6.3is driven by the piston6.11and6.21, reciprocally moving along the X direction. As a result, the pin6.5of the eccentric wheel7.1moves along the X direction as well. InFIG. 9, when the pin of the eccentric wheel pulls, the eccentric wheel7.1away from the kicker pin7.3, along the negative X direction, the steel strip5is pressed strongly. Then the pressed steel strip is pulled continuously, and consequently strap the package9firmly.

InFIG. 10, the working surface of the supporting table6.6A may be flat or serrated. The hardness of the steel strip is equal to or larger than 85 HRB. The surface of the steel strip contacting the working surface is serrated, leading to strong friction that enhances the tension strength.

The hinge system:

InFIG. 2andFIG. 8, a hinge system8is disposed on the front ends of the two tensioning cylinders. The hinge system8includes a hinge pin8.12disposed along the Y direction, a cutter frame8.2and a hinge return spring8.3.FIG. 8andFIG. 9show that the hinge pin is fixed on the rear end surface2.1B of the back plate2.1of the support frame2via two trunnion seats2.4placed along the Y direction.

InFIG. 9, the cutter frame includes two side frames8.21and a cutter platform8.22under the side frame8.21. The side frames are respectively fixed onto the two tensioning cylinders along the X direction. InFIG. 8, the two side frames are sleeved around the two ends of the hinge pin through a hole drilled on the side frame.

FIG. 2shows that the front end of the hinge return spring is placed in a spring hole2.1A on the back plate2.1, while the opposite end is put into another spring hole8.2A of the cutter frame.

InFIG. 2, there are two situations that the steel strip is not under tension. The first one is when the steel strip is cut by the cutter, and the second one is under the not working condition. When these two situations happen, the hinge return spring8.3would return to its initial state, pushing the tensioning section to a further position away from the clamping and cutting section. Due to the hinge connection, the tensioning section would rotate around the hinge pin8.1, subsequently forming an angle δ between the axis of tensioning cylinders and the X axis.

InFIG. 2andFIG. 8, when under the working condition, the tensioning section rotates around the hinge pin, compressing, the hinge return spring8.3. At the same time, the steel strip is under tension.FIG. 4shows that during the working condition, the front end surface8.2B of the cutter frame contacts the back end surface2.1B of the back plate. The angle δ is 0. The hydraulic fluid port10, the cable11, the handrail12, the button13and the hitch lug14in perspective view are shown inFIG. 4.

InFIG. 9andFIG. 11, the steel strip5contains a bent section to avoid the movement thereof. A free end of the steel strip firstly passes through the buckle4from the back end. The free end then forms a loop around a package9, and passes through the buckle4from the front end. InFIG. 10, the other end of the steel strip is placed between the eccentric wheel7.1and the supporting table6.6.

InFIG. 2, in order to avoid the movement of the buckle4during pulling the steel strip5, a lock plate2.5is fixed onto the back plate2.1of the support frame2.

InFIG. 5andFIG. 9, the tensioning mechanism7includes the eccentric wheel7.1and the supporting table6.6, which are pulled by the tensioning cylinders6.1and6.2. As a result, the steel strip is movable along the negative X direction. The tensioning spring7.2provides counter torque that allows the steel strip to be pressed more firmly.

InFIG. 6andFIG. 9, when the tension on the steel strip achieves the required value, the clamping cylinder is actuated. The cylinder pin3.3subsequently moves down, driving the edges of the connecting rods to bite against the buckle, and form the bite points4.1and4.2. Meanwhile the steel strip5is clamped strongly by the buckle4. Then the pressing part3.4is driven by the cylinder pin3.3, and presses the cutter3.6. The steel strip5could be cut by the cutter3.6together with the transverse cutter3.8. Finally, the piston of the clamping cylinder moves up. The linkage mechanism and the pressing part return to their initial positions. Without the pressure created by the pressing part3.4, the return spring3.7brings the cutter3.6back to the limited rod3.5.