Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/10—Moulds or cores; Details thereof or accessories therefor with incorporated venting means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/30—Mounting, exchanging or centering
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/30—Mounting, exchanging or centering
  • B29C33/301—Modular mould systems [MMS], i.e. moulds built up by stacking mould elements, e.g. plates, blocks, rods
  • B29C33/302—Assembling a large number of mould elements to constitute one cavity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
  • B29D30/52—Unvulcanised treads, e.g. on used tyres; Retreading
  • B29D30/54—Retreading
  • B29D30/56—Retreading with prevulcanised tread
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
  • B29D30/52—Unvulcanised treads, e.g. on used tyres; Retreading
  • B29D30/58—Applying bands of rubber treads, i.e. applying camel backs
  • B29D2030/582—Venting air inclusions, e.g. air trapped between tread and carcass

Definitions

• the present invention is in the field of tire molds. Background of the Invention During the molding of the tire, it is necessary to be able to evacuate all the air which might be imprisoned between the tire introduced into the mold and the different parts of the mold. If the slightest pocket of imprisoned air remains between the mold and the tire, this will cause a molding defect which appears on the outer surface of the tire. Such molding defects are unacceptable both from the standpoint of the quality of the tire manufactured and from the standpoint of its aesthetic appearance. Now, it is l ⁇ iown that it is impossible to assure total venting of a mold naturally, that is to say, by simply using the spaces between the different component parts of the mold in- order to assure the evacuation of the air. Recourse is therefore had to various palliatives, one of which is of general use in the tire industry, namely the drilling of small vent holes wherever necessary in the mold.
• Figure 1 is an illustration of the tire tread mold of the present invention.
• Figure 2 is an illustration of one plate of the tire tread mold of the present
• Figure 3 shows a tread made with . the tire tread mold of the present invention.
• FIG 4 is an enlargement of the tread shown in Figure 3.
• the present invention is a process for making an entire truck tire tread comprising the steps of securing tread mold segments comprising plates to a flat backing, placing a blank tread on the mold segments, and pressing the blank tread against the mold segments.
• the invention also comprises this process wherein the tread mold segments comprising plates are formed by the steps of machining at least one side of a plate so that the peak to peak variation of the plate surface is less than 5 microns, securing the plates to a flat backing;, and machining a reverse tread pattern onto the secured plates.
• the present invention also comprises a process for making a mold for a tire tread comprising the steps of securing tread mold segments comprising plates of at least two different thicknesses to a flat backing, and machining a reverse head pattern comprising ridges onto the secured plates, where the thickness of the plate under the ridge is chosen so that the width to height ratio of a ridge on a plate is not less than 1:10.
• the present invention is a process for making an entire truck tire tread comprising the steps of securing tread mold segments comprising plates to a flat backing, placing a blank tread on the mold segments, and pressing the blank tread against the mold segments.
• the invention also comprises this process wherein the tread mold segments comprising plates are formed by the steps of machining at least one side of a plate so that the peak to peak variation of the plate surface is less than 5 microns, securing the plates to a flat backing; and macMning a reverse tread pattern onto the secured plates.
• the present invention also comprises a process for making a mold for a tire tread comprising the steps of securing tread mold segments comprising plates of at least two different thicknesses to a flat backing, and machining a reverse tread pattern comprising ridges onto the secured plates, where the thickness of the plate under the ridge is chosen so that the width to height ratio of a ridge on a plate is not less than 1:10.
• Figure 1 hows one embodiment of a segment of the tire tread mold ⁇ 10) of the present invention.
• Flat plates (20) are secured together, forming a segment of the complete mold.
• the plates (20) are secured by means of rods (60) . extending through apertures (50) in the plates.
• End piece (70) secures the plates together.
• a reverse of a tread pattern has been machined onto one side of the mold (10).
• This pattern comprises various ridges (40) and depressions (45).
• the plates (20) begin as blanks, such as shown in Figure 2
• the plates are made of aluminum approximately 10 millimeters thick.
• the plates are roughened on one or both of their major sides, so that the peak to peak maximum height difference on the machined surface is about 0.005 millimeters. This roughness permits venting of gases between the plates during the tread mold process, but is small enough to prevent the formation of flashing.
• a tread pattern is then machined onto the clamped-together plates (see Figure 1).
• the reverse tread pattern comprises ridges (40) and depressions (45).
• the height to width ratio of a ridge is no greater than 10:1. This preserves the strength of the tread mold pattern.
• the plates are of at least two different thicknesses.- That way, plates can be selected such that a ridge supported by a plate has a height to width ratio no greater than 10:1. In other words, thin features in the tread mold do not lie across two plates.
• Figure 4 is an enlargement of the tread shown in Figure 3
• Figure 4 shows almost unobservabie lines of flashing ( 100), less than 0J millimeter high.
• the use of the present invention results in a greatly improved tread appearance.
• the invention may be further understood by means of the following non-limiting example.
• a mold was constructed for a 215/65R16XZE-SA tire tread. Both sides of 6061 aluminum plate (3/8" or 9.525 mm) were roughened to permit venting, and clamped together. The tread pattern was machined into three sectors of tread (total length 889 millimeters). The mold face was then sandblasted. The sectors were secured in a press, and a. total of seven cures were made. The process was then repeated.
• FIG. 3 and Figure 4 show the results of the process.
• Venting performance The testing sectors were placed in the middle of the press, which is the worst position for causing venting quality control issues. After all 14 cures, none of the treads made by the test sectors had any venting quality control deficiencies. Besides that, even the backside of the sculpture had no venting deficiencies for all test 5 treads. This has been a venting problem for this particular sculpture. That means air pockets trapped on the backside of the tread may penetrate the rubber and vent through the gap in between the plates.
• Tire aspect The overall appearance is much better than a mono-block mold with vents made by a direct machining process. It looks the same- as a new tire by the Michelhi Id aspect standard. The stepping on the summit in -between the plates is mimmal They are visible, but not measurable.
• Flashing There was no flashing on one of the sectors with all plates machined on one side for the first curing test. There was no flashing on any of the 3 sectors for the second curing test. For that test, one sector had plates machined on one side, and other 5 two sectors had plates machined on both sides.
• the tread surface finish has the same quality as treads made by any other process
• the misalignment in-between the sectors was minimal. They are visible, but not measurable. That implied that the accuracy of the sector length and CNC machine three- dimensional accuracy is good. We expect that the three-dimensional accuracy of the mold 0 will be within several hundredths of a millimeter.
• the summit has sharp comers; the aspect around the summit is much cleaner and neat looking.
• the minimum radius in between the groove wall and the tread surface is 1.0 mm. No visible steps were created using in ' different finish cutting tools. It is a common problem in the direct sculpture machfning process. That is because all the finish tools are set into precision length and the spindle assembly of the CNC machine has compensation

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Tyre Moulding (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (2)

Family

ID=32713275

Family Applications (1)

Country Status (8)

Cited By (4)

Families Citing this family (2)

Citations (3)

Family Cites Families (1)

• 2003
  • 2003-12-15 EP EP03815210A patent/EP1585632A2/en not_active Withdrawn
  • 2003-12-15 BR BR0317952-4A patent/BR0317952A/pt not_active Application Discontinuation
  • 2003-12-15 WO PCT/US2003/039785 patent/WO2004062898A2/en not_active Application Discontinuation
  • 2003-12-15 AU AU2003297066A patent/AU2003297066A1/en not_active Abandoned
  • 2003-12-15 KR KR1020057012666A patent/KR20050098857A/ko not_active Application Discontinuation
  • 2003-12-15 JP JP2004566547A patent/JP2006519120A/ja not_active Withdrawn
  • 2003-12-15 CN CNA2003801083660A patent/CN1735504A/zh active Pending
  • 2003-12-15 CA CA002512548A patent/CA2512548A1/en not_active Abandoned

Patent Citations (3)

Non-Patent Citations (1)

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