Cdng nghiep rimg A N H H i r o f N G C U A D Q A M D E N S l f B I E N D O I N H I E T D O B E N T R O N G V A N
T R O N G Q U A T R I N H E P N H I E T C A O T A N V A N E P K H O I T R E Nguyen Thi Huwng GiangS Ho^ng Manh Thirdng^, Le Van Tung'
• Trudng Bgi hpc Ldm nghiep
^UBNDxa Tdn Khai. huypn Hdn Qudn, tinh Binh Phude T O M T A T
NghiSn cihi suf dyng van tre 6p khoi lam v|t liSu nghiSn cuai, vin tre din?c 6p nhiet cao tin diroi cic dilu ki^n dg am nguyen li^u khac nhau, trong qui trinh ep n h i ^ cao tin vin ep khoi tre ti^n hanh do su biin doi nhi?t d§
ben trong cua van, tir do phan tich v4 dua ra quy lu|it bi6n doi nhiet d^ ben trong van theo dp im. KSt qua nghifin ciiu cho thay, trong phgm vi difiu kien thi nghidm, nhi^t dp ciia vin tang cao r6 rang khi dp i m ciia thanh tre nguyen Iifiu tang tit 6- 18%, ham lurpng keo din 300 g/m^. Trong qui trinh tang nhiet dp co thfi phan tbanh 2 giai dogn la giai doan tang nhiet nhanh va giai doan tang nhiet cham. Trong giai doan tang nhiet nhanh, nhiet dp ben trong ciia van tSng cao theo sir tang dan cua dp Im flianh tre nguyfin li^u. Trong giai dogn tang nhi^t c h ^ d§ i m thanh tre nguyen Iifiu anh hirong rit it dfin t6c dp tang nhi?t dp bfin trong vin, t^c dfl tSng nhift cua lop giita giam din khi thoi gian gia nhi^t tSng len. Thong qua ket qua phan deh cua thi aghi|m, -nghien cmi da dira ra difiu kifin cflng ngh^ 6p nhiet cao tin.vin ep khdi tre vdi cic thong sfl: him lupng keo 300
g/ra^, dp am thanh tre 12%, thdi gian ep nhifit cao tin 10 phiit.
TIT khoa: Do am, bam lirang keo, nhi^t dS, thin gian ep nhiet cao tan, \&n ep kboi tre.
I. D^T VAN DE
Gia nhiSt eao tdn la mdt troug nhihig ky thudt gia nhiet mdi xudt hien trong 10 ndm trd lai day. Hien nay ky thuat ep nhiet cao tdn dang duge ung dimg rdng rai trong nganh ehe biSn Iam sdn. Qud trinh gia nhiet cao tdn khdng can bit cu phuong tien trung gian hay chdt ddn dien nao, ma nang lugng dien trudng true tiep dong vai trd lam phan tti dan dien, sir gia nhiet duge tien hanh ddng thdi tai tat ed cae vi Iri bSn trong chdt ddn dien. Ddc diem cua qua trinh gia nhiet eao tan la toe do gia nhiet nhanh, gia nhiet dong deu va cd tinh lyia chgn (Chen, Y.P., Wang, J.L., Li, C.S., Wang, Z.T., 2007; Wu, Z.H., 1994). Trong qua trinh ep nhiet cao tdn, nhiet do Id mdt trong nhiing thdng sd cdng ngh^ quan trgng nhdt (Wu, Z.
H., 1991), ddng thdi nd ciing la dieu kien tat yeu dS chdt kSt dinh dong rdn. DS ddm bdo cho chat kSt dinh ben trong van ddng ran tot nhdt, phdi dam bdo nhiet do ben trong vdn dat dugc nhi?t dg ddng ran yeu cdu.
Hien nay, tren thS gidi da cd mgt sd cdng trinh nghiSn cuu vS su tdng nhiet trong qua trinh ep nhiet vdn nhdn tao, nhung cac nghien
cuu nay vdn chu ySu tap trung vao nghien cuu doi vdi ep nhi?t van sgi, van dam, van ddn (Liu, X., Zhang, Y., Li, W.D., Jia, C , 2013;
Yu, M.C., Rao, J.P., Xie, Y.Q., 2011; Lei, Y.F., 2005...), ddi vdi gia nhiet cao tdn chu ySu tap trung vao nghien cuu cae nhan td tdn hao dien mdi (Anagnostopoulou-Konsta, A., Pissis.P., 1988; Torgovnikov, G.I., 1994;
William, L.J., 1975) vd say cao tan, cdn cac nghien cdu vS quy luat bien doi nhiet dg ben trong vdn trong dien trudng cao tdn thi rat it (Chen, Y.P., Wang, J.L., Li, C.S., Wang, J.P., 2011).
Td thuc tiln tren, tae gid dd sd dung thanh tre ldm nguyen li^u, keo PF lam chat ket dinh, thanh tre sau khi dugc quet keo, tien hanh xep van vd dng dung ky thudt cong ngh? gia nhigt cao tan trong dieu kien phdng thi nghi?m de tao van ep tre cd chi6u ddy 20 cm. Trong qud trinh ep van su dung may kiSm tra nhiet dg chuyen dung de kiem tra nhiet do tai cac diem ben trong vdn theo chieu nam ngang, tu dd tun ra quy ludt bien dg nhi?t do ben trong van trong di|n trudng eao tan vd lira chgn dugc thdi gian gia nhi^t, ham lugng keo, do dm thanh tre nguyen lieu tdi uu, ddm bdo dugc TAP CHI KHOA HQC VA CONG NGHE LAM NGHIEP THANG 10/2017 127
Cdng nghiep rung
chat ket dinh ben trong van dat dugc su ddng ran tdt nhat.
II. PHU'ONG PHAP NGHIEN CCtJ 2.1. V^t li^u
Thanh tre: Tre trdn, dugc eat thdnh cac thanh tre, sau dd bao 2 mat, bd di ldp ldi vd ldp vd. Sau dd tien hanh say thanh tre dS dat dugc dg dm td 10 - 12%. Thanh tre sau say, dugc edt thdnh hinh chu nhdt cd kich thudc dai x rgng x day Id 1000 x 20 x 5 mm. Sau dd thanh tre dugc cdt ngdn vdi chieu dai la 500 mm de su dyng trong qua trinh thi nghiem.
Chdt kSt dinh; Keo PF dugc mua do Cdng ty TNHH tre Chu Ky Quang Du ChiSt Giang, Trung Qudc san xuat. Su dung keo PF cd ham lugng ddng ran 46%, do pH 7,8.
2.2. Phuomg phap nghien cuu 2.2.1. Bo tri diem do nhipt dp
De tim ra xu the biSn ddi nhiet do ben trong vdn trong dien trudng cao tan phai tien hanh bd
tri nhieu diem do nhigt do theo chieu nam ngang cua Idp van ldi. Theo phuang ngang chgn 5 diSm do (nhu hinh 01), trong dd cac diSm I, m , IV, V dhi edch 30nun theo canh ddi va each 50 mm theo cgnh ngdn, diSm n Id diSm trung tam cua ldp van idi. Tdt ea cdc diem do dugc cdt theo dg sau nhdt dinh theo chiSu ddi cua thanh tre.
Bhifa 01. Biem do nhiet do 2.2.2. Kiem tra nhiet dp ben trong vdn
Qud trinh ep van va kiem tra nhiet do ben trong van nhu hinh 02.
^
Hinh 02. Qua trinh dp nhi|t cao t^n va Tre sau khi dugc dieu chinh d cae cdp do dm khdc nhau, tien hanh quet keo 2 mat vd xep ldp, sau do dua vao trong may ep cao tdn. Su dung phuang phdp gia nhiet theo chiSu thdng dung de ep vdn. Khi ket noi gja nhiet cao tdn, sii dung mdy do v ^ ndng dk kiSm tra tdc dg tang nhiet cda vdn. Sau khi tang nhiet 60s, tSt thiet bi cao tan de do nhiet do ben trong van d cac diSm do nhu hinh 01. Mdi ldn do lap lai 3 lan, sau dd lay gia tri trung binh. Sau moi ldn do, lai tiep tuc lap l?i viec ddng va md thiet bi eao tan cho den khi diem trung tdm cua vdn dat dugc nhiet do ddng rdn thi dirag qua trinh
kiem tra nhiet do ben trong vdn tre ep khoi ep nhiet.
Sd ligu do dugc su dung thdng ke toan hoc tren Excel de xii ly va phan tich su anh hudng eua cae thdng so ep den qua trinh thay doi nhiet dg ben trong van.
HI. K E T QUA VA THAO L U ^ Cdng suat nhiSt ma nguySn liSu tre hap thu trong dign trudng cao tdn cd thS dimg cong thuc vk mdt do cdng sudt dS thS hien nhu sau:
Pv=0.556fE^e" ^Iff^^W-cm'^
Trong d d : / - Tan sudt dign trudng,/ cd dinh;
E - Cudng dd dien dudng, cd quan he vdi chiSu day van va dien dp;
128 TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP THANG 10/2017
Cdng nghiep rimg e" - Tdn thdt di^n mdi, dugc tinh bdng tieh
ciia hang sd dien mdi va gdc tdn that dign mdi (William, L.J., 1975).
Tren cimg 1 mat phang ndm ngang, thi cudng do dien trudng E la cd dinh. Vi vdy nhau td chu ySu dnh hudng dSn tdc dd gia nhiet la t6n thdt dien mdi. T^n that dien mdi cd quan he mdt thiSt vdi do dm cua phdi vdn trudc khi ep. Khi do dm cua phdi van cao, tiic la thanh phan nude nhieu, md tdn thdt dien mdi cua nude cao gdp 320 ldn so vdi tdn thdt dien mdi ciia gd khd kiet (Chen, Y.P., Wang, J.L., Li, C.S., Wang, J.P., 2011), hdng sd dien mdi cua nude cao gap 40 lan so vdi gd khd kiet, gdc tdn Bang 01. Phdn bh nhi£t^5-ben trong van
thdt dign mdi cua nude cao gap 8 lan so vdi gd khd kiet (m^i^, n-^B, 1979; m^n, 1985). Khi do dm dudi diem bao hoa thd gd, gdc tdn thdt dien mdi tang khi d$ dm tang. Khi do am cao hon diem bao hda thd gd, gdc tdn thdt dien mdi gidm ddn khi do am tang len (Shi, W.C, Li, H.X., 1984). Vi vdy, do dm cua phdi van la nhdn td quan trgng nhat dnh hudng den su gia nhiet cua van.
Ket qua thi nghiem do nhiet do ben trong van d dieu kien thanh tre nguyen lieu cd cdc cap do dm la 6%, 12%, 18%, hdm lugng keo 300 g/m^ dugc t6ng hgp d bang 01.
ep nhiSt cao tin theo chieu nam ngang D ; am (%)
6
12
18
T h M gian gia nhiet cao tan (min)
0 1 2 3 4 5 6 7 8 9 10 0
1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
I#
8 43 65 78 94 102 108 118 122 126 132 8 57 71 84 96 108 116 128 131 137 140 8 70 74 85 87 96 102 115 122 127 132
Nhiet do (°C)
n#
8 45 67 87 102 109 115 126 130 135 140 8 67 78 95 105 114 122 130 135 140 143 8 75 80 93 96 103 109 119 130 135 140in#
8 42 62 74 91 99 105 116 122 126 132 8 54 68 80 92 105 114 126 130 135 140 8 69 72 82 84 92 98 112 120 125 130
IV#
8 38 58 69 88 97 103 115 120 125 131 8 55 65 77 90 102 112 125 128 135 138 8 65 70 80 79 88 95 109 116 122 130
V#
8 40 60 71 86 95 101 114 120 125 130 8 52 62 75 88 100 110 124 127 134 138 8 63 68 77 81 90 96 110 117 122 130
TAP C H i KHOA HOC VA CONG NGHE LAM NGHIEP THANG 10/2017 129
Cdng nghiip rung
Tir bdng 01 cho thdy, trong qud trinh gia nhigt cao tdn, xu the tang nhigt cua diem tnmg tdm va cac diem ngoai bien cua vdn khdng ddng nhat. Phdn tich tde do tdng nhiet tu diSm I# den diem V# phdt hien ra rdng, tdc dg tang nhigt d diem II# nhanh nhdt, sau do dSn diem I# va III#, tdc dg gia nhiet d diSm IV# va V#
rdt chdm.
Nhiet do diSm trung tam II# trong vdn khdc nhau theo su thay ddi eiia dd dm. Dua vao nhiet do cua diSm trung tdm trong vdn cd the nhan thay rang, vdn cd do am 12% dat dugc nhiSt dd ddng rdn keo yeu cdu rdt nhanh vdi ihdi gian gia nhiet la 7 phiit Van cd do dm nguyen lieu 6% va 18% can thai gian gia nhiet Id 8 phdt dS d^t duge nhiSt dd ddng rdn yeu cdu.
Cac diSm giap c ^ I#, III#, IV#, V# cua van cd do dm 12% dat dugc nhiet do ddng rdn
keo yeu cdu nhanh nhdt la 9 phut. Tiep dSn la vdn ed do dm 6% vd 18% vdi thdi gian gia nhigt ySu cdu Id 10 phut
Trong pham vi nghien ciiu do dm ctia thanh tre nguyen ligu td 6 -^ 18%, d gjan d o ^ tang nhigt nhanh, tdc do tang nhiet ben trong van theo thu tir tii cao den thdp theo do dm nguySn lieu cua vdn la 18% > 12% > 6%. Nhi^t dg a cac diSm ciia 3 loai vdn nay dat dugc nhi$t do ddng ran nhanh nhdt Id van cd dd dm nguyen lieu 12% vdi thdi gjan gia nhiet la 9 phut, tiep den la van cd do dm nguySu lieu 6% va 18%
vdi thdi gian gia nhiet Id 10 phut. NhiSt do ldp giiia trung binh d giai d o ^ tang nhiet cham cua van cd do am nguySn lieu 12% Id cao nhdt
Td so lieu d bang 01, sii dung Excel tien hanh phan tich tdc do tdng nhiet cua diem trung tdm II# bSn trong van dugc kSt qud nhu bang 02 va hinh 03.
160 150 140 130 120 110 100 P 90
^ 80 I 70
^ 60 50 40 30 20 10 0
1 3 4 5 6 7 8 10 11
Thai ™TI gia nhi& cao tan/tnoi
\. Sy tkay ddi D&iSt d6 d YI tri tnmg tdm ben trong rafl ghep tre d cac c;^ do am khac ohan
130 T ^ CHI KHOA HQC VA C 6 N G N G H ? LAM NGHIEP THANG 10/2017
Bang 02. Kik qua phan Nhan to Thoi gian ep nhiSt
Dd im
CSng nghiep rirng 1 tich 2 nhSn to Ididng lap or bang 01 v6i diem tmng tam cua van
df 9 2
F va Fcrit 102.96> F9,2,0.95=2.456 19.566>F9,2,0.95=3.554
r
< 0.00001 0.00003 Td hinh 03 ta thay, qua trinh tang nhiet bSn
trong van chia lam 2 giai doan la giai doan tang nhigt nhanh vd giai doan tang nhigt chdm.
d giai doan tang nhiet nhanh, nhiet do tang trong pham vi tu 8 ^ 90''C, su chenh lech ve tang nhigt dO gida cac diSm rdt ro rang, ddng thdi vdi vdn cd do dm nguyen ligu cao thi tdc do tdng nhiet do d cac diem do Id rdt nhanh.
Tdc do gia nhiet d diem trung tdm van vdi cac cap dd dm khdc nhau tang nhanh ban so vdi cdc diem do giap c?aih van. NguySn nhdn ddn dSn tdc dg gia nhiet cua diSm trung tam van n#
nhanh Id do vi tri trung tam (gida vdn) khd tdn nhiet, hoi nude ndng trong vdn nhiSu, van khdng cd hien tugng thodt nude ra ngoai, tde do tang nhigt rat nhanh, lam cho nhigt d$ trong van tang nhanh. Dieu nay diing vdi quy ludt eua gia nhiet cao tdn va cho thdy rang do am cd dnh hudng rat Idn den qua trinh tang nhiet do bSn trong van, dac biet la d giai doan tang nhiet nhanh.
Ci giai d o ^ tang nhiet chdm, nhiet do tang trong pham vi la sau 90 -^ IOO°C, nhiet do tnmg binh eua cac diem do trong vdn ddn ddn tuong ddng nhau theo sir ddng rdn cua keo eho dSn khi ket thuc qua trinh gia nhiSt. Do Ihanh phdn hai nude bdc hoi nhanh, tdc dg gia nhiet eiing giam xudng. Sau khi vdn dat nhiet do trSn 100°C, do keo dan bi gja nhiet, nen keo ddng rdn nhanh, lam cho nhiet dg tang chdm, anh hudng cua do am vdn den tdc do gia nhiet nhd, nguyen nhanh chu ySu Id d giai dostn nay phdn ldn nude bSn trong vdn da bdc hoi hSt, ddn den do dm bSn trong van giam xuong.
Vi vay, trong qua trinh gia nhiSt cao tdn,
nhiet dg khdng ngiing tang len, hoi nude dong vai trd Id chat truyen nhiet. Xu the nhiSt dd ben trong vdn theo chieu hudng tang nhanh trudc, tang ch$m sau.
Ci bang 02 cho thdy, thdi gian gia nhiet cd dnh hudng rdt ro rang dSn su tang nhiet ben Uong vdn ((P < 0,00001 < a = 0,05), do dm cd dnh hudng khd ro rang dSn su tdng nhiSt bSn trong van (P = 0,00003 < a = 0,05).
Tu kSt qud tren cho thay, cd the lira chgn dugc cac thdng sd ep nhiet cao tdn van ghep khdi tre nhu sau: do dm hgp ly cho thanh tre nguySn lieu khi su dimg ep van cao tan la 12%, thdi gian gia nhiet cao tdn la 10 phut.
IV. KET LUAN
Thdng qua nghien ciiu su phan bd nhiet do theo chiSu ndm ngang ben trong van d eae cdp do am khdc nhau, co the ket ludn nhu sau:
- Tdc do tang nhiet bSn trong van ghep khdi tre CO thS chia dianh 2 giai doan la giai doan tang nhiSt t6c do nhanh vd giai doan tang nhiet toe do chdm. Ci gjai doan tang nhiet tdc do nhanh, tdc do tang nhiet d cdc diem gidp canh cua van khdng ddng nhdt. O giai dogn tang nhiet tdc do cham, nhiet do eua cdc diSm ben trong vdn gan nhu nhau.
Trong pham vi nghien cdu, dg dm bSn trong van tdng len khi do dm cua nguyen lieu va va thdi gian gia nhiet cao tdn tang len. Van cd dg dm nguySn lieu 12% cd nhiet do trung binh cua Idp giiia d giai doan tang nhiet chdm cao nhdt. 6 cac diSu kien do dm khac nhau, de nhiet do eua cac dilm ben ttong van dat dugc nhiet dg dong ran yeu cau can thdi gian gja nhiet cao tdn la 10 phiit.
T ^ CHI KHOA HQC VA CONG NGHE LAM NGHIEP THANG 10/2017 131
Cdng nghiip rimg
- Thdi gian gia nhiet cao tan ed anh hudng rat rd rang den su tang nhiet bSn trong van, do dm cua nguyen lieu van ed anh hudng khd ro den sir tang nhiet bSn trong vdn. d giai doan tang nhiet tdc do nhanh thi dg dm nguySn ligu van va thdi gian gia nhiet cd anh hudng rat ro rang. Tuy nhien d giai doan tdng nhiet tdc do cham thi dg dm nguyen lieu van ed dnh hudng rdt nhd d^n su tang nhiet cua ldp giira van, tdc do tang nhiet ciia ldp giira van giam dan theo khi thdi gian gia nhigt eao tdn tang ISn.
TAI IA%V THAM KHAO
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flakeboard during hot pressing[D]. Beijing: Beijing Forestry University
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i^m&MAms^[M] m^^mii.
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132 T^P CHI KHOA HQC VA CONG NGHE LAM NGHIEP THANG 10/2017
Cdng nghiip rimg
EFFECT OF MOISTURE CONTENT ON VARIATION OF TEMPERATURE INSIDE THE MATS FOR GLUED-LAMINATED
BAMBOO BY HIGH-FREQUENCY HOT PRESSING PROCESS
Nguyen Thi Huong Giang^, Hoang Manh Thuong^ Le Van Tung^
• Vietnam National University of Forestry
^People's Committee of Tan Khai commune, Hon Quan district, Binh Phuoc province
S U M M A R Y
Glued laminated bamboo was chosen to study. It was hot pressed with high-frequency at different conditions.
The variation of temperature inside the mats for glued laminated bamboo (GLB) was measured durmg hot pressing. The results showed that with moisture content increasing from 6% to 18%, the amount of glue 300g/m^, temperature inside the mats increased significantly. Hot pressing can be divided into fast heating and slow beating phases. Ten^erature inside the mats increased with the mcreasing moisture content and pressing time during the first phase while the impact of moisture content and amoimt of glue on temperature inside the mats very small during the second phase. The heating rate of the core layer decreased with the increasmg pressing time during the second phase. Through the analysis results of the experiment, optimum high-frequency hot pressing technological parameters for glued laminated bamboo manufacturing were as follows: amount of glue 300g/m^, moisture content of bamboo splits 12%, pressing time of PF glued laminated bamboo were 10 minutes.
Keywords: Amount of spread, glued laminated bamboo, high-frequency, moisture content, pressing time, temperature.
Ngay nh^n bdi Ngdy phdn bifn Ngay quyet dinh ddng
04/9/2017 13/9/2017 22/9/2017
T ^ P CHI KHOA HQC VA C 6 N G NGHE LAM NGHIEP THANG 10/2017 133
