Plastic film cutter mechanism

Abstract

The utility model provides a kind of plastic film cutter mechanism, including fixed seat and cutting part, the cutting part is set on fixed seat, further include hot knife assembly, the hot knife assembly is movably assembled on fixed seat, the hot knife assembly includes heating unit, clamping knife block and the hot cutter for melting film, the heating unit is cooperated with clamping knife block to transfer energy to hot cutter, the fixed seat is equipped with the guide structure for guiding film, the cutting port is equipped in the position corresponding to the cutting edge of hot cutter of guide structure, when the hot knife assembly is relative to fixed seat activity, the distance between the cutting edge of hot cutter and cutting port can be adjusted. The plastic film cutter mechanism disclosed in the utility model is convenient to operate, and can effectively improve production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of plastic bag manufacturing technology, and more specifically, to a plastic film cutting mechanism. Background Technology

[0002] Film tubular material refers to a double-layered flat material formed by blow molding and flattening of plastic film. In the production process of plastic film bags, the folded edges of this tubular film usually need to be longitudinally cut to open it, so that the tubular material can be unfolded into a single film or made into a bag opening structure. At present, the industry generally uses cold blade cutting as the traditional edge opening method. However, this traditional cold cutting structure has significant technical defects: after long-term continuous operation, the cold blade gradually loses its sharpness due to mechanical wear, and the cutting process causes obvious tensile deformation of the film edge, resulting in a wavy edge, which seriously affects the appearance quality of the product and subsequent processing performance.

[0003] Subsequently, a method for cutting films using electrically heated blades was introduced. For example, a film slitting electric heating blade disclosed in Chinese patent CN203485242U includes a fixed shaft, a movable blade holder on the fixed shaft, a heating plate holder fixedly mounted on the blade holder, a cavity on the heating plate holder, a heating aluminum plate inside the cavity, a mounting hole inside the heating aluminum plate, a heating rod inside the mounting hole, a cover plate on the heating plate holder, and a blade between the cover plate and the heating plate holder. The front end of the blade extends out of the heating plate holder, and the purpose of slitting the film is achieved by heating the blade, thereby making the cut edge of the film smooth. However, this structure has obvious limitations: although the blade holder can be moved left and right or rotated on a fixed axis, it cannot achieve precise fine adjustment of the distance between the blade and the film. When facing films of different thicknesses, materials or process requirements, it is still necessary to disassemble the blade holder as a whole and adjust the blade extension length, or even replace the blades of different specifications. This results in cumbersome changeover operations, long debugging cycles, and difficulty in ensuring adjustment accuracy, making it difficult to meet the high efficiency and flexibility requirements of modern film bag making production. Utility Model Content

[0004] The purpose of this invention is to provide a plastic film cutting mechanism that is easy to operate and can effectively improve production efficiency.

[0005] The technical solution adopted by the plastic film cutting mechanism disclosed in this utility model is: A plastic film cutting mechanism includes a fixed base and a cutting component, the cutting component being disposed on the fixed base. It also includes a hot knife assembly movably mounted on the fixed base. The hot knife assembly includes a heating unit, a clamping block, and a hot cutting blade for melting the film. The heating unit cooperates with the clamping block to transfer energy to the hot cutting blade. The fixed base is provided with a guide structure for guiding the film. The guide structure has a cutting opening at a position corresponding to the blade of the hot cutting blade. When the hot knife assembly moves relative to the fixed base, the distance between the blade of the hot cutting blade and the cutting opening can be adjusted.

[0006] As a preferred embodiment, the hot knife assembly further includes a movable block connected to the clamping block. The movable block has an oblong hole extending along the adjustment direction of the hot knife assembly. A groove is provided at the opening of the oblong hole. The fixed base has a mounting hole communicating with the oblong hole. A connector passes through the mounting hole and the oblong hole to realize the movable connection between the movable block and the fixed base.

[0007] As a preferred embodiment, the connecting component is a locking bolt. The head of the locking bolt is embedded in the sinker and fits against the bottom surface of the sinker for positioning. The screw of the locking bolt passes through the oblong hole and is threadedly connected to the mounting hole. The movable block is locked onto the fixed seat by tightening the locking bolt.

[0008] As a preferred embodiment, a heat insulation sleeve is provided between the movable block and the clamping block, the heat insulation sleeve being used to prevent the heat from the clamping block from being transferred to the movable block.

[0009] As a preferred embodiment, the clamping blocks are arranged symmetrically, and each clamping block has a fixing groove on its inner side. After the two sets of clamping blocks are connected by fasteners, the handle of the hot cutting knife is clamped and fixed between the fixing grooves of the two clamping blocks.

[0010] As a preferred embodiment, the heating unit is a heating tube, and the clamping block is provided with a cavity that matches the shape of the heating tube. The heating tube is embedded in the cavity and fits tightly with the fixing groove of the clamping block.

[0011] As a preferred embodiment, the hot knife assembly is further provided with a temperature sensor, which is fixed to the top of the clamping block by screws, and the detection end of the temperature sensor is set in close contact with the clamping block.

[0012] As a preferred embodiment, the cutting element is a cold blade, which is detachably connected to the fixing base via a clamping plate. The clamping plate is provided with an adjusting screw for adjusting the installation height of the cold blade.

[0013] As a preferred embodiment, the inner surface of the cut is an inclined surface or a circular arc surface.

[0014] As a preferred embodiment, the top of the guide structure is provided with an arc surface to avoid scratching the film.

[0015] The beneficial effects of the plastic film cutting mechanism disclosed in this utility model are as follows: by using a hot cutting blade to melt and cut thermoplastic films at high temperatures, the film stretching deformation and wavy edge defects caused by wear of traditional cold blades are effectively avoided, resulting in smooth and flat cut edges and significantly improving product quality. At the same time, by movably mounting the hot blade assembly on the fixed base, the distance between the cutting opening on the guide structure and the hot cutting blade can be flexibly adjusted. Without the need to completely disassemble the blade holder or replace the blade, it can quickly adapt to the cutting needs of films of different thicknesses and materials, making operation convenient and effectively improving production efficiency. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of the plastic film cutting mechanism of this utility model.

[0017] Figure 2 This is an exploded view of the plastic film cutting mechanism of this utility model.

[0018] Figure 3 This is an exploded view of the fixed base and cutting component in the plastic film cutting mechanism of this utility model.

[0019] Figure 4 This is a schematic diagram of the working state of the plastic film cutting mechanism of this utility model. Detailed Implementation

[0020] The present invention will be further described and illustrated below with reference to specific embodiments and the accompanying drawings: Please refer to Figure 1 A plastic film cutting mechanism includes a fixed base 10, a cutting element 20, and a hot blade assembly 30. The cutting element 20 is disposed on the fixed base 10 and is a cold blade. The hot blade assembly 30 is movably mounted on the fixed base 10 and is located above the cold blade. The fixed base 10 is provided with a guide structure 11 for guiding the film. The guide structure 11 is provided with a cutting opening 12 that cooperates with the hot blade assembly 30 for cutting the folded edge 2 of the tubular film 1.

[0021] Please refer to Figure 2 The hot knife assembly 30 includes a heating unit 31, a clamping block 32, a hot cutting blade 33, and a movable block 34. The movable block 34 is fixedly connected to the clamping block 32 by connecting bolts 37. The clamping blocks 32 are arranged symmetrically, and each clamping block 32 has a fixing groove 321 on its inner side. After the two sets of clamping blocks 32 are connected by fasteners, the handle of the hot cutting blade 33 is clamped and fixed between the fixing grooves 321 of the two clamping blocks 32. The blade of the hot cutting blade 33 extends out of the clamping block 32 and corresponds to the cutting opening 12. The heating unit 31 is located inside the clamping block 32 for heating the hot cutting blade 33.

[0022] In this embodiment, the movable block 34 is provided with an oblong hole 341 extending along the adjustment direction of the hot knife assembly 30. A groove 3411 is provided at the opening of the oblong hole 341. The fixed base 10 is provided with a mounting hole 13 communicating with the oblong hole 341. A connector 35 passes through the mounting hole 13 and the oblong hole 341. The connector 35 is a locking bolt. The head of the locking bolt is embedded in the groove 3411 and fits against the bottom surface of the groove 3411 for limitation. The screw of the locking bolt passes through the oblong hole 341 and is threadedly connected to the mounting hole 13. The movable block 34 is locked on the fixed base 10 by tightening the locking bolt.

[0023] When adapting to films of different thicknesses, the operator uses a wrench to loosen the locking bolt, making the movable block 34 movable. Then, the operator pushes the hot knife assembly 30 along the length of the oblong hole 341, causing the blade of the hot cutting knife 33 to move closer to or away from the cutting edge 12. The gap is adjusted to the target value by measuring with a dial indicator or feeler gauge. For example, for a 0.05mm thick PE film, it can be adjusted to 1.5mm. Finally, the locking bolt is tightened, with its head pressing against the bottom surface of the recess 3411, firmly locking the movable block 34 onto the fixed seat 10, thus completing the adjustment. The locking bolt and the oblong hole 341 enable quick unlocking, stepless adjustment, and reliable locking. The entire adjustment process is simple and convenient, and takes less time compared to the traditional method of replacing the knife holder.

[0024] In another embodiment, a miniature linear guide rail is fixedly mounted on the fixed base 10, and the extension direction of the guide rail is perpendicular to the film surface. A slider that mates with the guide rail is machined at the bottom of the movable block 34, and a radial locking screw is provided on the slider. Through the precise sliding of the slider on the guide rail, the hot knife assembly 30 is moved as a whole, thereby achieving precise adjustment of the distance between the blade of the hot cutting knife 33 and the cutting opening 12. After adjustment, the radial locking screw on the slider is tightened, causing its end face to press against the side of the guide rail, firmly locking the slider and the hot knife assembly 30 onto the fixed base 10. This structure has higher guiding accuracy and repeatability compared to the waist-shaped hole 341 adjustment method, and is particularly suitable for high-speed film production lines or applications with extremely high requirements for edge cutting quality.

[0025] A heat insulation sleeve 36 is provided between the movable block 34 and the clamping block 32. The heat insulation sleeve 36 is fitted onto the surface of the connecting bolt 37. The heat insulation sleeve 36 is a hollow cylindrical sleeve with an inner diameter slightly larger than the diameter of the rod of the connecting bolt 37. It is made of high-temperature resistant ceramic material. During installation, the heat insulation sleeve 36 is first fitted onto the connecting bolt 37, then passed through the mounting holes 13 of the movable block 34 and the clamping block 32, and locked with the nut. At this time, the heat insulation sleeve 36 is compressed between the contact surfaces of the movable block 34 and the clamping block 32, which is used to block the heat from the clamping block 32 from being transferred to the movable block 34, preventing the movable block 34 from deforming due to heat and affecting the adjustment accuracy. At the same time, it reduces heat loss and improves the thermal efficiency of the heating unit 31.

[0026] The clamping blocks 32 are two symmetrically arranged heat-conducting metal bodies connected by fastening bolts evenly distributed along the length of the blade handle. When a locking torque is applied to the fastening bolts, the two clamping blocks 32 close together, clamping and fixing the blade handle of the hot cutting blade 33 between the fixing grooves 321 to form a rigid whole. The shape of the fixing grooves 321 is adapted to the blade handle of the hot cutting blade 33, transferring heat through surface contact and restricting the movement of the blade handle, preventing the hot cutting blade 33 from shifting or loosening during cutting vibration.

[0027] The heating unit 31 is disposed inside the clamping block 32 and is embedded in the cavity 322 of the clamping block 32. In this embodiment, the heating unit 31 is a heating tube, which is connected to an external power source via a power cord. The heat generated by the heating tube is evenly transferred to the handle of the hot cutting blade 33 through the clamping block 32, causing the blade to heat up rapidly to the film melting temperature. Through the high-temperature melting action of the hot cutting blade 33, the cylindrical film 1 is cut open at the cutting opening 12. Since the film is separated by melting rather than mechanical tearing, the film experiences little deformation during cutting, resulting in a smooth and flat edge without wavy edges, thereby improving the product's appearance quality and subsequent processing performance.

[0028] The hot blade assembly 30 is also equipped with a temperature sensor 40, which is fixed to the top of the clamping block 32 by screws, with the sensing end of the temperature sensor 40 in close contact with the clamping block 32. The temperature sensor 40 monitors the temperature of the clamping block 32 in real time and feeds the temperature signal back to an external temperature controller. The temperature controller performs closed-loop adjustment of the heating tube power according to the preset temperature value, so that the temperature of the hot cutting blade 33 is stabilized within the process range required for film melting, preventing excessive melting of the film due to excessive temperature or insufficient cutting due to excessively low temperature, and ensuring the stability and consistency of cutting quality.

[0029] Please refer to Figure 3The cold blade is detachably connected to the fixed base 10 via the clamping plate 14. The cutting element 20 is disposed between the clamping plate 14 and the fixed base 10. The fixed base 10 is provided with a mounting groove corresponding to the clamping plate 14. When the clamping plate 14 is inserted into the mounting groove, the side wall of the mounting groove restricts the horizontal displacement of the clamping plate 14. The bottom surface of the mounting groove provides rigid support for the clamping plate 14, thereby significantly improving the vibration resistance and positioning accuracy of the clamping plate 14 and preventing the clamping plate 14 from loosening or shifting due to film tension fluctuations during the cutting process.

[0030] The inner surface of the cutting opening 12 is an inclined surface or an arc surface, which is adapted to the shape of the cutting edge of the hot cutting blade 33, forming a guiding cutting channel. When the cutting edge of the hot cutting blade 33 enters the cutting opening 12, the inclined or arc surface of the inner surface acts as a guide, allowing the cutting edge to smoothly insert into the cutting opening 12, avoiding rigid interference or collision between the cutting edge and the inner surface of the cutting opening 12, thereby protecting the cutting edge from damage and extending the service life of the hot cutting blade 33.

[0031] During the cutting operation, the inner surface of the inclined or arc-shaped surface can guide the molten film material to pass smoothly through the cutting area, preventing the molten material from accumulating, adhering, or flowing back in the cutting opening 12, keeping the cutting opening 12 clean and unobstructed, thereby ensuring the smoothness and flatness of the film opening edge and improving the cutting quality.

[0032] Please refer to Figure 4Overall workflow: At the initial stage of the blown film machine startup, the tubular film 1 moves from top to bottom in the direction of the arrow under the action of traction force. The operator manually or with the help of an auxiliary blade makes an initial cut at the folded edge 2 of the tubular film 1. Then, the guide structure 11 on the fixed seat 10 is inserted into the tubular film 1 and hooks the folded edge 2 of the tubular material outward in the horizontal direction, so that the folded edge 2 is close to the outer surface of the guide structure 11, ensuring that the film maintains a stable posture and tension during the movement. When the folded edge 2 of the tubular material moves downward to the hot cutting blade 33, since the hot cutting blade 33 has not been heated, it cannot melt the folded edge 2 of the tubular material. The tubular material turns around the tip of the hot cutting blade 33 and continues to move downward to the cold blade. The cold blade cuts open the folded edge 2 of the tubular material, completing the pre-cutting of the film. Once the operating parameters of the blown film machine are adjusted and stabilized, the heating power supply of the hot cutting blade 33 is turned on, supplying power to the heating element inside the hot blade assembly 30. The heat generated by the heating element is conducted to the clamping block 32, which then evenly transfers the heat to the hot cutting blade 33. The temperature sensor 40 monitors the temperature of the clamping block 32 in real time and feeds the signal back to the external temperature controller, ensuring that the blade temperature of the hot cutting blade 33 is stably maintained above the melting point of the film material. This ensures that the blade has the ability to instantly melt and cut the tubular film 1 at the fold 2. When the hot cutting blade 33 reaches its working temperature, the upstream tubular material fold 2 enters the cutting area 12. The blade of the hot cutting blade 33 cuts the tubular film 1 at the fold 2 through high-temperature melting. Because the melting and cutting method has minimal mechanical stretching effect on the film, the edge of the film after cutting is smooth and flat, effectively avoiding the wavy edge defects produced by traditional cold cutting processes. After being thermally cut open, the film continues to move downwards, where downstream cold blades perform a fine-tuning and cutting of the molten edges, ensuring complete separation of the film and further improving the neatness of the cut edges.

[0033] After the film is split open, its two edges continue to move downward along the metal surface at the bottom of the cutter holder. The two sides of the metal cutter holder rapidly dissipate heat and cool the film edges through thermal conduction, causing the film edge temperature to drop quickly below the softening point. This ensures that the two edges of the film will not re-adhere due to residual heat or static electricity, thus ensuring that the film remains in a stable, single-sheet separated state and providing reliable film material for subsequent winding or bag-making processes.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A plastic film cutting mechanism, comprising a fixed base and a cutting component, wherein the cutting component is disposed on the fixed base, characterized in that, It also includes a hot knife assembly, which is movably mounted on a fixed base. The hot knife assembly includes a heating unit, a clamping block, and a hot cutting blade for melting the film. The heating unit cooperates with the clamping block to transfer energy to the hot cutting blade. The fixed base is provided with a guide structure for guiding the film. The guide structure has a cutting slit at a position corresponding to the blade of the hot cutting blade. When the hot knife assembly moves relative to the fixed base, the distance between the blade of the hot cutting blade and the cutting slit can be adjusted.

2. The plastic film cutting mechanism as described in claim 1, characterized in that, The hot knife assembly also includes a movable block connected to a clamping block. The movable block has an oblong hole extending along the adjustment direction of the hot knife assembly. A groove is provided at the opening of the oblong hole. The fixed base has a mounting hole communicating with the oblong hole. A connector passes through the mounting hole and the oblong hole to realize the movable connection between the movable block and the fixed base.

3. The plastic film cutting mechanism as described in claim 2, characterized in that, The connecting component is a locking bolt. The head of the locking bolt is embedded in the sinker and fits against the bottom surface of the sinker for positioning. The screw of the locking bolt passes through the oblong hole and is threadedly connected to the mounting hole. The movable block is locked on the fixed seat by tightening the locking bolt.

4. The plastic film cutting mechanism as described in claim 2, characterized in that, A heat insulation sleeve is provided between the movable block and the clamping block, which is used to prevent the heat from the clamping block from being transferred to the movable block.

5. The plastic film cutting mechanism as described in claim 1, characterized in that, The clamping blocks are arranged symmetrically, and each clamping block has a fixing groove on its inner side. After the two sets of clamping blocks are connected by fasteners, the handle of the hot cutting knife is clamped and fixed between the fixing grooves of the two clamping blocks.

6. The plastic film cutting mechanism as described in claim 5, characterized in that, The heating unit is a heating tube, and the clamping block has a cavity that matches the shape of the heating tube. The heating tube is embedded in the cavity and fits tightly with the fixing groove of the clamping block.

7. The plastic film cutting mechanism as described in claim 1, characterized in that, The hot knife assembly is also equipped with a temperature sensor, which is fixed to the top of the clamping block by screws, and the detection end of the temperature sensor is closely attached to the clamping block.

8. The plastic film cutting mechanism as described in claim 1, characterized in that, The cutting element is a cold blade, which is detachably connected to the fixed base via a clamping plate. The clamping plate is provided with an adjusting screw for adjusting the installation height of the cold blade.

9. The plastic film cutting mechanism as described in claim 1, characterized in that, The inner surface of the cut is an inclined surface or a circular arc surface.

10. The plastic film cutting mechanism as described in claim 1, characterized in that, The top of the guide structure has an arc surface to avoid scratching the film.

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