OPTIMISATION OF THE DYNAMIC INDICATOR OF INTERACTION BETWEEN CHISELS AND THE WOOD OF THE CONICAL FACE MILLING CUTTERS (WITH SMALL NUMBER OF CHISELS) OF SAWING MACHINES
The work is related to the study and optimisation of the dynamic performance of interaction between chisels and the wood in the course of longitudinal milling using the conical face milling cutters (with small amount of chisels) of sawing machines. This dynamics is characterized by non-uniformity of the process load when using the specified milling cutters. It was quantitatively assessed by the indicator of non-uniformity of the technological load within the cycle of processing of logs and bars into sawn timbers and wood chips. For cutters with small number of chisels this dynamic indicator equals the ratio of the maximum total length of the cutting edges of the chisels to the average length of their cutting edges simultaneously involved in cutting throughout the cycle of wood processing (turn of the cutter). Conical face milling (conical) cutters with a small number of chisels were conventionally considered as a discrete set of square-shoulder mills, i.e. as a particular case of a cutter with many chisels. The process of interaction with between the chisels and wood within the processing cycle was divided into four zones (periods): I zone – period of cutting of all chisels into the timber; II zone - period of operation of all chisels of a group and subsequent extraction from timber; III zone – the period of gradual extraction of the group of chisels from the timber; IV zone – period of approaching the neighbouring group of chisels. The size and relative orientation of these zones in time in conditions of steady cutting define the different nature of interaction between chisels and the wood with the varying intensity of technological load. Author has obtained mathematical relationships between these zones, and taking them into account – determination of the index of uneven technological load per wood processing cycle; calculations were made and a number of parameters of cutters were substantiated. The author has determined the influence on the rate of non-uniformity of width, height of milling, as well as the angle of rotation of chisels in the centre plane of the cutter. The rational (optimal) location of double lip chisels (at two-row structure) on the milling cutter body is the following: the ratio of the width of a line of chisels with larger radius of cutting to the width of a line of chisels with smaller radius of cutting (at the calculated values of the milling process) is 1.25; the size of the non-covered area of the cutting edge at the smaller base of the cutter is 50 mm with a total width of 120 mm. This condition corresponds to the minimum maximum power of cutting along the length of the chips cut and the lowest indicator of uneven technological load per turn of the cutter.
1. Avksent'ev, M.P. Frezernyj instrument dlja agregatnogo oborudovanija. Tezisy dokladov k Vsesojuznomu seminaru «Sostojanie i osnovnye napravlenija razvitija agregatnogo lesopilenija v tekushhej pjatiletke i na perspektivu» [Milling tool for modular equipment. Abstracts of reports to the All-Union Seminar "Status and trends of development of aggregate sawing in the current five-year period and for the future"]., М.P. Avksent'ev., Central'nyj nauch.-issled. in-t mehan. obrab. drev. CNIIMOD [Central Research Institute for Machine Processing of Wood CRIMPW]. - Arhangel'sk, 1985., pp. 25-32.
2. Borovikov, E.M. Lesopilenie na agregatnom oborudovanii [Sawmilling using the aggregate equipment]., E.M. Borovikov, L.A. Fefilov, V.V. Shestakov. - Moskva., Lesnaja promyshlennost' [Timber Industry]., 1985. - 216 p.
3. Grube, A.Je. Derevorezhushhie instrumenty [Woodworking Tools]., A.E. Grube. - Moskva., Lesnaja promyshlennost' [Timber Industry]., 1971. - 343 p.
4. Pat. 1782732 Rossijskaja Federacija, MPK4 V27, G13/02, 13/04. Torcovo-konicheskaja malonozhevaja freza [Patent No. 1782732, Russian Federation, MPK4 B27, G13/02, 13.04. Conical face cutter with small number of chisels]., V.V. Taratin, A.P. Tarutin; zajavitel' i patentoobladatel' Central'nyj nauch.-issled. in-t mehan. obrab. drev. [The applicant and the patentee - Central Research Institute for Machine Processing of Wood]. – No. 4840963/15; zajavl. 23.12.90; opubl. 23.12.92. Bjul. No. 47 [Application 23.12.90; published on 23.12.92. Bulletin No. 47]. - 47 p.
5. Senkevich, L.V. Sovershenstvovanie konstruktivnyh parametrov malonozhevyh torcovo-konicheskih frez dlja frezerno-pil'nogo oborudovanija [Improvement of design parameters of conical face cutters with small number of chisels for sawmill equipment]., avtoref. dis.... kand. tehn. nauk [Abstract of the Thesis by the Candidate of Technical science]. 05.21.05.SPb., LTA. – St. Petersburg., 1994. – 22 p.
6. Taratin, V.V. Lesopil'nye agregaty: sovremennoe sostojanie i tendencii ih sovershenstvovanija [Sawmilling aggregates: the current state and trends of their improvement]., V.V. Taratin., Derevoobrab. prom-st' [Timber industry]. - 1998., No. 1., pp. 3-6.
7. Fronius, K. Spaner Kreissägen Bandsägen., K. Fronius. – Stuttgart., DRW-Verlag, 1989 - 300 p.