Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/60—Making other particular articles cutlery wares; garden tools or the like
  • B21D53/64—Making other particular articles cutlery wares; garden tools or the like knives; scissors; cutting blades
  • B21D53/647—Making other particular articles cutlery wares; garden tools or the like knives; scissors; cutting blades mower blades

Definitions

• the invention relates to a method for manufacturing cutting blades for a mower, especially a so-called cyclo mower, whereby - departing from a material strip of which the thickness corresponds to the thickness of the cutting blades, and of which the width corresponds to the length of the cutting blades,
• - successive transections are made approximately in transversal direction across a significant part of the width of the strip such that the section of the strip between two successive transections forms a cutting blade.
• a method of the above-mentioned type is known from US 2521059.
• the blanks manufactured by this method need some further processing before they can be assembled together with spiders to form a cutter reel for a lawn mower. After the cutting operation a cuutmg edge has to be formed by any suitable means along one edge of the blade. Then the blade has to twisted slightly to obtain its desired final form.
• This method comprises a relatively large number of operating processes, each having an influence on the price of the final product.
• An object of the invention is now to provide a method which uses only a relatively small number of method steps so that a relatively cheap product can be made.
• a further object of the invention is to extend the effective working life by providing the product with a special shape. In an indirect manner therewith the price/performance ratio is influenced in a favourable way.
• Figure 1 illustrates in which way rectangular cutting blades according to the invention are made from a material strip.
• Figure 2 illustrates a schematical cross section through an embodiment of a tool, which can be used to cut off the cutting blades from the strip material.
• Figure 3 illustrates a schematical cross section through a preferred embodiment of the tool which can be used to transect the cutting blades from the material strip
• Figure 4 illustrates schematically how trapezium shaped cutting blades according to the invention can be made out of a material strip.
• FIG. 5 illustrates other shapes of cutting blades which can be made within the scope of the invention
• Figure 6 illustrates in a perspective view a ready made cutting blade which has an undulated profile in cross section
• Figure 7 illustrates an embodiment of a method according to the inven ⁇ tion whereby the transections are not made over the whole width of the material strip.
• Figure 8 illustrates a cutting blade with twisted central section.
• Figure 9 illustrates a variant of the method illustrated in figure 7.
• Figure 1 illustrates schematically in which way rectangular cutting blades can be made from a material strip
• the material strip, which m figure 1 is referenced by 10 has a width which corresponds to the length of the cutting blades to be made and has a thickness corresponding to the thickness of the cutting blades to be made.
• the material strip is moved stepwise in the direction 12 and passes thereby in region A a punching machine or another suitable apparatus by means of which the holes 14 are punched in the strip.
• each ready cutting blade has one or more of these holes 14 functioning for mounting the cutting blade to the rotor of the mowing machine.
• the strip After leaving region A the strip is further transported to a region B in which an apparatus is installed for separating the cutting blades from the end of the strip by means of a shortening operation.
• the last cutting blade, produced in this manner is indicated by 16.
• the dash and dot lines mark the locations where the successive transections are carried out to make clear in which way the strip is divided into cutting blades.
• Conceivable is a grinding or sawing operation, but these operations are relatively expensive.
• a much cheaper operation is cutting off the end sec ⁇ tion of the strip such that the resulting blade 16a has in any case one bevelled side edge 17 which can be used as cutting edge.
• Figure 2 illu ⁇ strates very schematically how such a cutting operation can be performed using a cutting knife 18 and an anvil 19. The cutting knife 18 could even- tually make an inclined downwards movement such that the respective cutting edge 17 is indeed obtained.
• FIG. 3 illustrates such an appa- ratus very schematically.
• the apparatus comprises a lower die 20a and an upper die 20b, both comprising an elongated ridge with an approximately sinusoidal cross sectional shape.
• the dies 20a and 20b are mounted in the schematically indicated parts 22 and 24 of a press, which press can be operated such that the dies 20b and 20a are moved towards each other.
• each cutting blade is preferable to provide that part of the cutting blade which in fact is subject to the strongest wear during use of the blade, with a larger width so that more material can be worn off before the cutting blade has to be replaced. It is preferred therefore to embody the cutting blades not with a rectangular shape but with a trapezium shape in a way as sche ⁇ matically is illustrated in figure 4.
• the strip 10 is transported in the direc- tion of the arrow first again through a station A where the necessary holes 14a are made in the strip by means of a punching operation.
• the pattern of holes 14a is in this case different because now the cutting blades will be separated from the strip m a head-tail-pattern.
• the strip is transported further to region B where the shortening operation is performed in such a manner that the transecting lines extend not exactly in width direction but in an alternating order make a positive or negative angle with the transversal direction.
• the shortening operation is performed in such a manner that the transecting lines extend not exactly in width direction but in an alternating order make a positive or negative angle with the transversal direction.
• the result thereof is that in the way illustrated in figure 3 trapezium-shaped cutting blades are separated from the end of the strip.
• the positions of the succeeding tran ⁇ sections are indicated by dash and dot lines which make clear how the cut ⁇ ting blades are formed out of the strip.
• the resulting cutting blades 16c have near the holes 14a a relatively small width. This part of the cutting edge is not or hardly subject to any wear. With increasing distance from the hole 14a also the width of the blade increases so that at the side of the cutting blade, where the wear of the blade is the most heaviest, the most material is present. Because there is a lot of material to wear off the effective work ⁇ ing life of the cutting blade is increased significantly.
• Figure 5 illustrates three examples of differently shaped blades.
• Figure 5a illustrates a knife 16d whereby the transition between the small section and the broad section is made stepwise.
• Figure 5b illustrates a knife 16e, whereby the transition between the small section and the broad section is made fluently with a sinusoidal shape.
• Figure 5c illustrates a knife 16f whereby the transition between the small section and the broad section is made through a sloped intermediate section.
• the succeeding transections by means of which the knives are separated from the strip and by means of which the cutting edges are shaped, have a mirror-symmetrical pattern in relation to a line transverse to the length direction of the strip.
• Figure 6 illustrates in a perspective view a knife 16g with a trapezium shape and furthermore provided with an undulation in length direction of the blade. How such an undulation is made is considered to be known and such an undulation is in many cases necessary to be able to correctly mount the blade to the rotor of the mowing machine. Such an undulation can be realized very easily by using a strip material 10 which as such is already provided with this undulation.
• the operation of manufacturing the blades can be performed further as described in relation to the figures 1 or 4 with the difference that the shortening operation has to be performed with a suitably shaped cutting knife 18 and anvil 19 or suitably shaped dies 20a and 20b. To reduce the therewith corresponding costs it can have its advan ⁇ tages to amend the method in some way. In this respect the attention is drawn to figure 7.
• FIG 7 Shown again in figure 7 is the strip 10 which is transported m the direction of the arrow 12 stepwise along the operating stations. It is assumed that trapezium-shaped blades are made from the strip 12 in a simi ⁇ lar manner as is illustrated in figure 4. For that purpose first of all the strip is transported along a punching machine in region A, where the holes 14b are made in the desired pattern Thereafter in region B the transec ⁇ tions are made. In contrast with the method as illustrated in figure 4 not the complete shortening operation is performed, but transections are made along almost the complete width of the strip 12 such that at least one not transected location remains. This location is referenced by 22 in figure 7. Instead of one not transected location also two or if necessary more not transected locations can be realized.
• the various parts remain connected and can be transported stepwise to a next operation region, indicated by C in figure 7.
• the band is for instance transported through a press by means of which the undulation is pressed in the material.
• This press can be embodied such that during the pressing operation the last knife 16h is simultaneously separated from the strip
• the press can also be embodied such that the strip after the pressing operation still is integrally intact so that the various blades 16h still have to be separated from the strip.
• the blade 16h has the same shape as the blade 16g which is illustrated in figure 6.
• Knits with an undulated shape instead of knives with an undulated shape also knives with an other non- flat shape can be applied.
• An example thereof is illustrated in figure 8.
• the cutting blade 16k which is illustrated in a perspective view has a twisted central section such that the smaller part, wherein the mounting hole is punched and the broader part, will not be in the same plane and will not extend parallel to each other.
• a similar order of operating steps can be applied as described with reference to figure 7, i.e. the holes are punched in region A, the non- complete transections are made in region B, and the shape pressing operation and separating ope ⁇ rations are carried out in region C.
• the concept of initially making non complete transections can be brought into practice in other different manners.
• Figure 9 illustrates how, after punching the necessary holes 14c in region A, in region B transections are made which end at a short distance from the edge of the strip material 10.
• the transections are in this case embodied such that in fact a small strap of material is removed between the succeeding blades whereby the blades are only connected at their both ends
• This embodiment of the transections can have advantages during the following operation in region C.
• region C the shaping operation is performed to obtain for instance blades of the type illustrated in figure 8
• the press used for this operation, can be embodied such that during the shaping process the blade is also separated from the strip.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19763055

Family Applications (1)

Country Status (4)

Families Citing this family (4)

Family Cites Families (2)

• 1996
  • 1996-06-21 NL NL1003397A patent/NL1003397C2/nl not_active IP Right Cessation
• 1997
  • 1997-06-20 AU AU31931/97A patent/AU3193197A/en not_active Abandoned
  • 1997-06-20 WO PCT/NL1997/000346 patent/WO1997048508A1/en not_active Application Discontinuation
  • 1997-06-20 EP EP97927476A patent/EP0907435A1/de not_active Withdrawn

Non-Patent Citations (1)

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