Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
  • B26D1/00—Cutting through work characterised by the nature or movement of the cutting member or particular materials not otherwise provided for; Apparatus or machines therefor; Cutting members therefor
  • B26D1/0006—Cutting members therefor
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
  • A24B7/00—Cutting tobacco
  • A24B7/02—Cutting tobacco by machines with reciprocating knives
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
  • A24B7/00—Cutting tobacco
  • A24B7/04—Cutting tobacco by machines with revolving knives
  • A24B7/08—Cutting tobacco by machines with revolving knives with several knives which act one after the other
  • A24B7/12—Cutting tobacco by machines with revolving knives with several knives which act one after the other with cutter axes transverse to the feeding direction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
  • B26D1/00—Cutting through work characterised by the nature or movement of the cutting member or particular materials not otherwise provided for; Apparatus or machines therefor; Cutting members therefor
  • B26D1/0006—Cutting members therefor
  • B26D2001/006—Cutting members therefor the cutting blade having a special shape, e.g. a special outline, serrations

Definitions

• This invention relates to a knife blade for a cutting machine, particularly but not solely for machines used to cut tobacco leaf.
• a machine to which the invention may be applied, used for cutting tobacco leaf is of a well known type in which the leaf is fed into a convergent throat of rectangular cross section formed by two parallel plates and two converging conveyor bands or by two parallel plates and two converging roller conveyors. At the convergent end of the throat is a mouthpiece. The leaf is fed into the throat at the divergent end and is driven by the conveyor bands or rollers towards the mouthpiece.
• the leaf is cut as it issues as a plug from the mouthpiece either by a single knife blade caused to reciprocate across the mouthpiece or by one or more knife blades arranged on a drum which rotates on an axis either at right-angles or parallel to the width of the throat, so that the cutting edge of each blade is caused to pass across the mouthpiece cutting off that portion of the plug that has emerged.
• the convergence of the throat compresses the leaf sufficiently so that it may be cut and not pulled from the mouthpiece.
• One of the two band or roller conveyors is free to move and pressure is applied so that the compression of the leaf can be regulated.
• the width of cut of the shreds can be adjusted by altering the conveyor speed and hence the distance the compressed leaf is fed through the mouthpiece between cuts by the knife or knives.
• a knife blade for such a machine is disclosed in United Kingdom Patent Specification No. 1195163, and comprises a steel plate having one surface bevelled to produce a cutting edge and a plurality of grooves formed at right angles to the cutting edge in the surface of the knife which is not bevelled thereby providing a crenellated cutting edge.
• An object of the present invention is to provide a knife blade for a cutting machine providing a progressive cutting action to further improve the cutting efficiency.
• a knife blade for a cutting machine comprising a plate having a cutting edge, and a plurality of generally V-shaped grooves formed in one surface of the plate transverse to the cutting edge, the cutting edge being formed by a bevel surface extending from the other surface of the plate back to the grooved one surface thereby providing a saw-tooth-1ike cutting edge.
• FIGURE 1 shows in end elevation part of a knife blade having grooves of V-shaped cross-section
• FIGURE 2 shows the knife blade of Figure 1 in plan
• FIGURE 3 is a section on the line A-A of Figure 2;
• FIGURE 4 is a side elevation of a rotary cutting machine
• FIGURE 5 is an axial elevation of the drum carrying a number of knife blades according to Figures 1, 2, and 3;
• FIGURE 6 is a schematic cross-section of a knife blade passing through a tobacco plug in a rotary cutting machine of Figure 4. DESCRIPTION OF PREFERRED EMBODIMENTS
• the knife blade 10 as shown in Figures 1 to 3 is a steel plate having an overall thickness of about 3 mm and is bevelled at one edge in the manner of a conventional knife blade to form a cutting edge 12.
• "V"-shaped cross section transverse grooves 11 are cut, in the embodiment at right angles to the cutting edge 12, in one surfaced of the plate having a pitch of from 7.5-40 mm, while the other surface is plane.
• the effect of the grooves and bevel is to produce a saw toothed cutting edge 12 with sharp, leading tips 12a having diverging trailing cutting edges 12t> on either side thereof.
• the angle ⁇ of the cutting edge 12fc) from the nominal line of the cutting edge through the tips 12a . is from 4-8 , preferably 5 .
• the knife blade is sharpened by grinding the bevel in the same way as a conventional knife blade.
• a particular knife blade suitable for cutting tobacco is ground with the bevel at an angle of about 18 degrees to the grooved face of the knife.
• the knife may be used in a reciprocating single knife cutting machine of the kind described in Patent No. 1195163 or in a rotary knife cutting machine as shown in Figures 4 and 5.
• tobacco is fed onto the space 32 between two converging conveyor belts 34 and 36 which carry the tobacco to a mouthpiece 38 and at the same time compress it so that it is driven through the mouthpiece as a plug.
• knife blade 10 is carried in holders 42 on drum 44 which rotates about an axis 46 parallel to the width of the mouthpiece, in bearings carried by arms 47.
• the cutting edges of the knife blade all lie on an imaginary cylindrical surface.
• the knife blades are arranged in this example with the grooves 11 away from the mouthpiece.
• a continuous sharpening of the blades by grinding can be effected by a grinding wheel 49 which has a drive mechanism for traversing it along the knife blades at a point remote from the mouthpiece, as they rotate on the drum 44 in use.
• the bevelled surface will be part cylindrical in this case. Al ernatively the knife blade may be brought in turn to a fixed grinding position and ground one at a time by a traversing grinding wheel of which the normal to the grinding face at the point of contact with the blade does not pass through the drum axis.
• the bevelled surface is flat and raked in relation to its cylindrical path.
• the saw teeth cutting edges 12t may be of more pronounced concave or convex shape, i.e. substantially triangular with concave or convex sides, if the V-shaped grooves are formed with concave or convex sides respectively.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Forests & Forestry (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacture Of Tobacco Products (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10638027

Family Applications (1)

Country Status (4)

Families Citing this family (3)

Family Cites Families (4)

• 1988
  • 1988-06-03 GB GB888813194A patent/GB8813194D0/en active Pending
• 1989
  • 1989-05-31 JP JP50654789A patent/JPH02504474A/ja active Pending
  • 1989-05-31 EP EP19890906807 patent/EP0371121A1/de not_active Withdrawn
  • 1989-05-31 WO PCT/GB1989/000596 patent/WO1989011802A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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