1. A method for laser welding comprising:
piling a resin workpiece being at least partly capable of laser-absorption onto a laser-transmissible resin workpiece for laser welding,
wherein:
said resin workpiece is a whitish resin material piece of polycarbonate as a thermoplastic resin including a laser absorbent that absorbs the laser beam of the wavelength for the laser welding, or a whitish resin material piece of polycarbonate as a thermoplastic resin applying a laser-absorptive layer including a laser absorbent that absorbs the laser beam of the wavelength for the laser welding,
the laser-transmissible resin workpiece, whose transmissivity is at least 15% under 840 nm of laser light, exhibits an opaque hue of white and a whiteness degree: W1 of the hue of at least 80, determined from the following numerical expression (I) using L-value, a-value and b-value of L*a*b color specification
W1=100\u2212\u221a{square root over ((100\u2212L)2+(a2+b2))}{square root over ((100\u2212L)2+(a2+b2))}\u2003\u2003(I),
said laser-transmissible resin workpiece is molded out of a laser-transmissible resin composition for laser welding comprising 100 parts by weight of polycarbonate as a thermoplastic resin and 0.01 to 3 parts by weight of titanium oxide that has a density of at least 4 gcm3, particles having an average particle size of 200 to 270 nm and oil absorption ranging from 15 g to 23 g per 100 g thereof,
surfaces of the titanium oxide particles are treated with a surface treatment agent that is selected from the group consisting of aluminum, alumina, aluminum-silicon, aluminum laurate, and aluminum stearate, and
said laser-transmissible resin composition exhibits a hue of white; and
irradiating a laser beam thereto to weld said resin workpiece and said laser-transmissible resin workpiece thermally.
2. The method for laser welding according to claim 1, wherein a refractive index n1 of said titanium oxide and a refractive index n2 of the thermoplastic resin satisfy following numerical expressions (1) and (2):
n1\u2212n2\u22671.0\u2003\u2003(1)
1.4<n2<1.7\u2003\u2003(2).
3. The method for laser welding according to claim 1, wherein the laser-transmissible resin composition further comprises 0.01 to 1 parts by weight of a laser-transmissible colorant to 100 parts by weight of the thermoplastic resin.
4. The method for laser welding according to claim 1, wherein the laser-transmissible resin composition further comprises at least one inorganic filler selected from the group consisting of talc, mica, calcium hydrogencarbonate, calcium carbonate, glass fiber, glass flake, glass beads, wollastonite and barium sulfate.
5. The method for laser welding according to claim 1, wherein the laser-transmissible resin composition further comprises an organic flame retarder.
6. The method for laser welding according to claim 1, wherein the whiteness degree: W1 ranges from 85 to 95.
7. The method for laser welding according to claim 1, wherein the resin workpiece being at least partly capable of the laser-absorption is made from a whitish resin material including a laser-absorbent being capable of the laser-absorption under region of 800 to 1200 nm of wavelength at least partially.
8. The method for laser welding according to claim 7, wherein the resin workpiece being at least partly capable of laser-absorption comprises:
a whitish resin material applied to a laser-absorptive layer comprising a laser-absorbent that is at least partially exhibits laser-absorption in a region of 800 to 1200 nm.
9. The method for laser welding according to claim 7, wherein the laser-absorbent is carbon black andor nigrosine.
10. The method for laser welding according to claim 7, wherein the hue of the laser-transmissible resin composition has a whiteness degree W2 of at least 80, wherein W2 is determined from the following numerical expression (II) using L-value, a-value and b-value of L*a*b* color specification:
W2=100\u2212\u221a{square root over ((100\u2212L)2+(a2+b2))}{square root over ((100\u2212L)2+(a2+b2))}\u2003\u2003(II).
11. The method for laser welding according to claim 8, wherein the laser-absorptive layer is a resin film including the laser-absorbent.
12. The method for laser welding according to claim 8, wherein the laser-absorptive layer is applied by ink andor paint including the laser-absorbent.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A cryocooler with variable compressions for cooling operation depending on variations in load, the cryocooler comprising:
a cylinder 110 which is internally filled with gas;
a piston 120 which rectilinearly reciprocates on an inner circumference of the cylinder 110 and compresses or expands the gas;
a connecting rod 130 which comprises a first side coupled to the piston 120 and moving together with the piston 120, and a second side formed with a first thread 131 along an outer circumference thereof;
a liner motor 140 which is disposed at a position opposite to a direction where the connecting rod 130 is extended, and rectilinearly reciprocates a motor shaft 141 toward the connecting rod 130 in accordance with a control signal; and
a sleeve 150 which is shaped like a cylinder, both sides of which are opened, so that an end portion of the motor shaft 141 can be supported by and inserted in one open side of the sleeve 150, and the second side of the connecting rod 130 can be inserted in the other open side of the sleeve 150, and an inner circumference of the sleeve 150 is formed with a second thread 151 to be engaged with the first thread 131 of the connecting rod 130 and rotate so that a distance D between the motor shaft 141 and the connecting rod 130 can be adjusted.
2. The cryocooler according to claim 1, further comprising a rotary motor 160 which is adjacent to one side of the sleeve 150 and comprises a rotary motor shaft 161 formed a the motor shaft gear 162,
wherein an outer circumference of the sleeve 150 is formed with a sleeve gear 152 engaging with and rotating together with the motor shaft gear 162.
3. The cryocooler according to claim 1, wherein a notch 142 protrudes from the end portion of the motor shaft 141 and is in contact with and supported by the inner circumference of the sleeve 150 so that the motor shaft 141 can be prevented from being inserted in the sleeve 150 by a predetermined length or longer.
4. The cryocooler according to claim 3, wherein a supporting protrusion 153 protrudes from a one-side inner circumference of the sleeve 150 so that the notch 142 of the motor shaft 141 can be in contact with and supported by the supporting protrusion 153.
5. The cryocooler according to claim 4, wherein the notch 142 has an annular shape along a circumference of the end portion of the motor shaft 141.
6. The cryocooler according to claim 5, wherein one end portion of the sleeve 150 is formed with a separation preventing protrusion 154 protruding inwardly to prevent the notch 142 of the motor shaft 141 inserted in the sleeve 150 from being separated outward from the sleeve 150.
7. The cryocooler according to claim 1, wherein the length of the second thread 151 formed on the inner circumference of the sleeve 150 is determined within a stroke distance of the piston 120.
8. The cryocooler according to claim 1, further comprising a controller 170 which outputs a control signal for driving control of the linear motor 140 and the rotary motor 160.
9. The cryocooler according to claim 8, wherein the rotary motor 160 comprises a step motor or a servo motor of which a rotating direction and a rotating angle can be precisely adjusted in accordance with a control signal of the controller 170.
10. The cryocooler according to claim 8, wherein the controller 170 previously stores a separate data storage space with cooling temperature variation data corresponding to the compression or expansion of gas in accordance with the rotating angles of the rotary motor 160, reads out the cooling temperature variation data corresponding to setting temperature control information or load variation information from the data storage space, and outputs a control signal for controlling the rotating direction or the rotating angle of the rotary motor 160.